Maxwell T. Masters

As full details relating to the disposition or arrangement of the general organs of flowering plants are given in all the ordinary text-books, it is only necessary in this place to allude to the main facts at present known, and which serve as the standard of comparison with which all morphological changes are compared.

Even in the case of the roots, which appear to be very irregular in their ramification, it has been found that, in the first instance at least, the rootlets or fibrils are arranged in regular order one over another, in a certain determinate number of vertical ranks, generally either in two or in four, sometimes in three or in five series. This regularity of arrangement (Rhizotaxy), first carefully studied by M. Clos, is connected with the disposition of the fibro-vascular bundles in the body of the root. This primitive regularity is soon lost as the plant grows.

In the case of the leaves there are two principal modes of arrangement, dependent, as it would seem, on their simultaneous or on their successive development; thus, if two leaves on opposite sides of the stem are developed at the same time, we have the arrangement called opposite; if there are more than two, the disposition is then called verticillate or whorled. On the other hand, if the leaves are developed in succession, one after the other, they are found to emerge from the stem in a spiral direction. In either case the leaves are arranged in a certain regular manner, according to what are called the laws of Phyllotaxis, which need not be entered into fully here; but in order the better to estimate the teratological changes which take place, it may be well to allude to the following circumstances relating to the alternation of parts. The effect of this alternation is such, that no two adjacent leaves stand directly over or in front one of the other, but a little to one side or a little higher up. Now, in the alternate arrangement the successive leaves of each spiral cycle alternate one with another till the coil is completed. For the sake of clearness this may be illustrated thus:—Suppose the spiral cycle to comprise five leaves, numbered 1, 2, 3, 4, 5, then 2 would intervene between 1 and 3, and so on, while the sixth leaf would be the commencement of a new series, and would be placed exactly over 1. This arrangement may be thus formularised:

6 7 8 9 10
1 2 3 4 5

In the verticillate or simultaneous arrangement of leaves the case is somewhat different. Let us suppose a whorl of eight leaves, surmounted by a similar whorl of eight. In such a case it will generally be found that the whorls alternate one with another, as may be represented by this symbol:

9 10 11 12 13 14 15 16
1 2 3 4 5 6 7 8

The simplest illustration of this arrangement is seen in the case of decussate leaves, where those organs are placed in pairs, and the pairs cross one another at right angles. This may be expressed by the following symbol:

7 8
5 6
3 4
1 2

Thus, while in both the annular and the spiral modes of development the individual members of each complete series necessarily alternate one with another, in the former case the series themselves alternate, while in the successive arrangement they are placed directly one over the other. There are, of course, exceptions, but the rule is as has been stated, and the effect is to prevent one leaf from interfering with the development and growth of its neighbours.

In the case of the whorled or simultaneous arrangement the conditions of growth must be uniform on all sides, but in the successive or spiral disposition the conditions influencing growth act with unequal force, on different sides of the stem, at the same time. In the whorl there is an illustration of radiating symmetry, while in the spiral arrangement there is a transition to the bilateral symmetry. There are frequent passages from one to the other even under normal circumstances; thus, while the one arrangement obtains in the ordinary leaves, the parts of the flower may be disposed according to the other method. In the annular disposition it generally happens that the rings are separated one from the other by the development of the stem between them, the internodes between the constituent leaves themselves of course being undeveloped; on the other hand, in the spiral or successive arrangement there is no such alternate growth and arrest of growth of the stem between the leaves, or between successive cycles, but the growth is, under favorable conditions, continuous—leaf is separated from leaf, and cycle from cycle, by the continually elongating stem. Thus, the two modes of growth correspond precisely with those observed in the case of definite and indefinite inflorescence respectively.

Fig. 1.—Diagram showing the arrangement of parts in a complete, regular, pentamerous flower: s, sepals; p, petals; st, stamens; o, ovaries.

The same arrangements, that are observed in the disposition of the leaves, apply equally well to the several parts of the flower; thus, in what is for convenience considered the typical flower, there is a calyx of five or more distinct sepals, equal in size, and arranged in a whorl, a corolla of a similar number of petals alternating with the sepals, five stamens placed in the same position with reference to the petals, and five carpels alternating with the stamens. Throughout this book this arrangement is taken as the standard of reference. Nevertheless the spiral order does occur in the floral leaves as well as in those of the stem; it often happens, especially when the organs are numerous, that they form spiral series; and the same holds good very generally, when the parts of the flower are uneven in number, as in the very common quincuncial arrangement of the sepals, &c.

To these general remarks, intended to show the agreement between the disposition of the leaves of the stem and those of the flower, it is merely necessary to add that the arrangement of the placentas, as well as that of the ovules borne on them, is also definite, and takes place according to methods explained in all the text-books, and on which, therefore, it is not necessary to dilate in this place.

The branches of the stem or axis correspond for the most part in disposition with that of the leaves from the axils of which they originate, subject, however, to numerous disturbing causes, and to alterations from the usual or typical order brought about by the development of buds. These latter organs, as it seems, may be found in almost any situation, though their ordinary position is in the axil of a leaf or at the end of a stem or branch.

The points just mentioned are of primary importance in structural botany, and as such are seized on not only by the morphologist, but by the systematic botanist, who finds in them the characters by which he may separate one group from another. Thanks to the labours of those observers who have devoted their attention to that difficult but most important branch of study, organogeny, or the investigation of the development of the various organs, and to the researches of the students of comparative anatomy or morphology, the main principles regulating the arrangement and form of the organs of flowering plants seem to be fairly well established, though in matters of detail much remains to be cleared up, even in such important points as the share which the axis takes in the construction of the flower and fruit, the nature of the placenta, the construction of the ovules, and other points.

The facts already known justify the adoption of a standard or typical arrangement as just mentioned. The intrinsic value of this type is shown by the facility with which all varieties of form or arrangement may be explained by reference to certain modifications of it. It must, however, be considered as an abstraction, and should be looked on in the light rather of a scaffolding, which enables us to see the building and its several parts, than of the edifice itself, but which latter, from our imperfect knowledge and limited powers, we could not see without some such assistance.

The typical form may be, hypothetically at least, considered as the primitive one transmitted by hereditary descent from generation to generation, and modified to suit the requirements of the individual, or in accordance with circumstances. If it be borne in mind that it is but an artificial contrivance, more or less true—a means to an end, and not the end itself—no harm will arise from its employment; and as knowledge increases, or as circumstances demand, the hypothetical type can be replaced by another more in accordance with the actual state of science.

Teratological changes in the arrangement of organs depend upon arrest of growth, as when parts usually spirally arranged remain verticillate, owing to the non-development of the internodes, or to excessive growth, or development; but in many instances it is impossible, without studying the development of the malformed flower, to ascertain whether the altered arrangement is due to an excessive or to a diminished action. Practically, however, it is of comparatively little importance to know whether, say, the isolation of parts, that are usually combined together, is congenital (i.e. the result of an arrest of growth preventing their union), or whether it be due to a separation of parts primitively undivided; the effect remains the same, though the cause may have been very different.

The principal alterations to be mentioned under this head may therefore be conveniently arranged under the following categories:—Union, Independence, Displacement, Prolification, Heterotaxy, and Heterogamy.

PART I.
UNION OF ORGANS.

The union of parts, usually separate in their adult condition, is of very common occurrence as a malformation. The instances of its manifestation admit of being grouped under the heads of Cohesion, where parts of the same whorl, or of the same organ, are united together; and of Adhesion, where the union takes place between members of different whorls, or between two or more ordinarily wholly detached and distinct parts. In either case, the apparent union may be congenital (that is, the result of a primitive integrity or a lack of separation), or it may really consist in a coalition of parts originally distinct and separate. In practice it is not always easy to distinguish between these two different conditions. Indeed, in most cases it cannot be done without tracing the development of the flower throughout all its stages. It is needless to make more than a passing allusion to the frequency with which both congenital integrity or subsequent coalescence of organs exist under ordinary circumstances. Considered as a teratological phenomenon, union admits of being grouped into several subdivisions, such as Cohesion, Adhesion, Synanthy, Syncarpy, Synophty, &c. Each of these subdivisions will be separately treated, but it maybe here said that, in all or any case, the degree of fusion may be very slight, or it may be so perfect that there may be a complete amalgamation of two or more parts, while to all outward appearance the organ may be single. The column of Orchids may be referred to as an illustration under natural circumstances of the complete union of many usually distinct parts.

In the uncertainty that exists in many cases as to the real nature of the occurrence, it would be idle to attempt to explain the causes of fusions. It is clear, however, that an arrest of development will tend towards the maintenance of primordial integrity (congenital fusion), and that pressure will induce the coalition of organs primarily distinct.

CHAPTER I.
COHESION.

Following Augustin Pyranius De Candolle, botanists have applied the term cohesion to the coalescence of parts of the same organ or of members of the same whorl; for instance, to the union of the sepals in a gamosepalous calyx, or of the petals in a gamopetalous corolla. It may arise either from a union between organs originally distinct, or more frequently from a want of separation between parts, which under general circumstances become divided during their development. Nothing is more common as a normal occurrence, while viewed as a teratological phenomenon it is also very frequent. For the purposes of convenience it admits of subdivision into those cases wherein the union takes place between the branches of the same plant, or between the margins of the same leaf-organ, or between those of different members of the same whorl.

Cohesion between the axes of the same plant.—This cohesion may occur in various manners. Firstly. The branches of the main stem may become united one to the other. Secondly. Two or more stems become joined together. Thirdly. The branches become united to the stem; or, lastly, the roots may become fused one with another.

Fig. 2—Cohesion of two branches in Dipsacus sylvestris.

The first of these is most commonly met with, doubtless owing to the number of the branches and the facilities for their union. An illustration of it is afforded by the figure (fig. 2), showing cohesion affecting the branches of a teazle (Dipsacus sylvestris). Union of the branches may be the result of an original cohesion of the buds, while in other cases the fusion does not take place until after development has proceeded to some extent. Of this latter kind illustrations are common where the branches are in close approximation; if the bark be removed by friction the two surfaces are very likely to become united (natural grafting). Such a union of the branches is very common in the ivy, the elder, the beech, and other plants. It may take place in various directions, lengthwise, obliquely, or transversely, according to circumstances. This mode of union belongs, perhaps, rather to the domain of pathology than of teratology. Some of the instances that have been recorded of very large trees, such as the chestnut of Mount Ætna, are really cases where fusion has taken place between several of the branches, or suckers, thrown out from the same original stem.[10] The same process of grafting occurs sometimes in the roots, as in Taxus baccata mentioned by Moquin, and also in the aerial roots of many of the tropical climbing plants, such as Clusia rosea, &c.

Fig. 3.—Fasciation in Lettuce.

Fasciation.—In the preceding instances of union between the branches, &c., the actual number of the fused parts is not increased; but if it happen that an unusual number of buds be formed in close apposition, so that they are liable to be compressed during their growth, union is very likely to take place, the more so from the softness of the young tissues. In this way it is probable that what is termed fasciation is brought about. This is one of the most common of all malformations, and seems to affect certain plants more frequently than others. In its simplest form it consists of a flat, ribbon-like expansion of the stem or branch; cylindrical below, the branches gradually lose their pristine form, and assume the flattened condition.

Fig. 4.—Fasciation in Asparagus.

Fig. 5.—Fasciated branch of Pinus Pinaster.

Very generally the surface is striated by the prominence of the woody fibres which, running parallel for a time, converge or diverge at the summit according to the shape of the branch. If the rate of growth be equal, or nearly so, on both sides, the stem retains its straight direction, but it more generally happens that the growth on one side is more rapid and more vigorous than on the other, and hence arises that curvature of the fasciated branch so commonly met with, e.g. in the ash (Fraxinus), wherein it has been likened to a shepherd's crook. It is probable that almost any plant may present this change. It occurs alike in herbaceous and in woody plants, originating in the latter case while the branches are still soft. It may be remarked that, in the case of herbaceous plants, the fasciation always affects the principal stem, while, on the other hand, in the case of trees and shrubs the deformity occurs most frequently in the branches; thus, while in the former it may be said that the whole of the stem is more or less affected, in the latter it is rare to see more than one or two branches of the same tree thus deformed. It is a common thing for the fasciated branch to divide at the summit into a number of subdivisions. These latter may be deformed like the parent branch, or they may resume the ordinary aspect of the twigs.

Fig. 6.—Fasciation and spiral torsion in the stem of Asparagus.

Sometimes the flattened stem is destitute of buds, at other times, these organs are scattered irregularly over its surface or are crowded together in a sort of crest along the apex. When, as often happens, the deformity is accompanied with a twisting of the branch spirally, the buds may be placed irregularly, or in other cases along the free edge of the spiral curve. In a specimen of Bupleurum falcatum mentioned by Moquin the spiral arrangement of the leaves was replaced by a series of perfect whorls, each consisting of five, six, seven, or eight segments, and there was a flower-stalk in the axil of each leaf.

When flowers are borne on these fasciated stems they are generally altered in structure; sometimes the thalamus itself becomes more or less fasciated or flattened, and the different organs of the flower are arranged on an elliptical axis. A case of this nature is described by Schlechtendal ('Bot. Zeit.,' 1857, p. 880), in Cytisus nigricans, and M. Moquin-Tandon describes an instance in the vine in one flower of which sepals, petals, stamens, and ovary were abortive, while the receptacle was hypertrophied and fasciated, and bore on its surface a few adventitious buds.[11] The pedicels of Streptocarpus Rexii have also been observed in a fasciated state.[12]

It has been occasionally observed that the fasciated condition is hereditary; thus, Moquin relates that some seeds of a fasciated Cirsium reproduced the same condition in the seedlings,[13] while a similar tendency is inherited in the case of the cockscomb (Celosia).

With reference to the nature of the deformity in question there is a difference of opinion; while most authors consider it to be due to the causes before mentioned, Moquin was of opinion that fasciation was due to a flattening of a single stem or branch. LinnÆus, on the other hand, considered such stems to be the result of the formation of an unusual number of buds, the shoots resulting from which became coherent as growth proceeded:—"Fasciata dici solet planta cum plures caules connascuntur, ut unus ex plurimis instar fasciÆ evadat et compressus" (Linn., 'Phil. Bot.,' 274). A similar opinion was held by J. D. Major in a singular book entitled 'De PlantÂ, Monstrosa, Gottorpiensi,' Schleswig, 1665, wherein the stem of a Chrysanthemum is depicted in the fasciated condition.

Fig. 7.—Fasciation in the scape of the Dandelion (Leontodon Taraxacum).

The striÆ, which these stems almost invariably present, exhibit the lines of junction, and the spiral or other curvatures and contraction, which are so often met with, may be accounted for by the unequal growth of one portion of the stem as contrasted with that of another. Against this view Moquin cites the instances of one-stemmed plants, such as Androsace maxima, but, on the other hand, those herbaceous plants having usually but a single stem not unfrequently produce several which may remain distinct, but not uncommonly become united together. Prof. Hincks[14] cites cases of this kind in Primula vulgaris, Hieracium aureum, and Ranunculus bulbosus. I have myself met with several cases of the kind in Primula veris, in the Polyanthus, in the Daisy, and in the Leontodon Taraxacum, in which latter a fusion of two or more flower-stems bearing at the top a composite flower, and made up of two, three, four, or more flowers combined together, and containing all the organs that would be present in the same flowers if separate, is very common.

Moquin's second objection is founded upon the fact that, in certain fasciated stems, the branches are not increased in number or altered in arrangement from what is usual; but however true this may be in particular cases, it is quite certain that in the majority of instances a large increase in the number of leaves and buds is a prominent characteristic of fasciated stems.

Another argument used by the distinguished French botanist to show that fasciated stems are not due to cohesion of two or more stems, is founded on the fact that a transverse section of a fasciated stem generally shows an elliptical outline with but a single central canal. On the other hand, if two branches become united and a transverse section be made, the form of the cut surface would be more or less like that of the figure 8[symbol: 8 turned 90°], although in old stems this may give place to an elliptical outline, but even then traces of two medullary canals may be found. This argument is very deceptive, for the appearance of the transverse section must depend, not only on the intimacy of their union, but also on the internal structure of the stems themselves. When two flowers cohere without much pressure they exhibit uniting circles somewhat resembling the figure of 8[symbol: 8 turned 90°], but when more completely combined they have an outline of a very elongated figure, and something similar is to be expected in herbaceous stems. Even the elongated pith of a transversely cut, woody, fasciated stem only marks the intimate union of several branches, and Prof. Hincks, whose views the writer entirely shares, has noticed instances of the union of two, and of only two, stems where the internal appearance was the same as in other fasciations.

Moquin, moreover, raises the objection that it is unlikely that several branches should become united lengthwise in one plane only, and, further, that in the greater number of fasciations all the other branches which should be present are to be found—not one is wanting, not one has disappeared, as might have been anticipated had fusion taken place. In raising this objection, Moquin seems not sufficiently to have considered the circumstance that the buds in these cases are in one plane from the first, and are all about equal in point of age and size.

The last objection that Moquin raises to the opinion that fasciation is the result of a grafting process is, that in such a case, examples should be found wherein the branches are incompletely fused, and where on a transverse section traces of the medullary canals belonging to each branch should be visible. The arrangement of leaves or buds on the surface should also in such a case indicate a fusion of several spiral cycles or whorls. To this it may be replied that such cases are met with very frequently indeed. A figure is given by De Candolle[15] of a stem of Spartium junceum having several branches only imperfectly fasciated.

Fasciated stems, then, seem to be best explained, as is stated by Prof. Hincks, "on the principle of adhesion arising in cases where from superabundant nourishment, especially if accompanied by some check or injury, numerous buds have been produced in close proximity, and the supposition that these growths are produced by the dilatation of a single stem is founded on a false analogy between fasciated stems and certain other anomalous growths."

It will not, of course, be forgotten that this fasciated condition occurs so frequently in some plants as almost to constitute their natural state, e.g. Sedum cristatum, Celosia, &c. This condition may be induced by the art of the gardener—"Fit idem arte, si plures caules enascentes cogantur penetrare coarctatum spatium et parturiri tanquam ex angusto utero, sic sÆpe in Ranunculo, Beta, Asparago, Hesperide Pinu, CelosiÂ, Tragopogone, Scorzoner Cotula foetida," LinnÆus op. cit.

Plot, in his 'History of Oxfordshire,' considers fasciation to arise from the ascent of too much nourishment for one stalk and not enough for two, "which accident of plants," says Plot, the German virtuosi ('Misc. Curios. Med. Physic. Acad. Nat. Cur.,' Ann. i, Observ. 102,) "think only to happen after hard and late winters, by reason whereof, indeed, the sap, being restrained somewhat longer than ordinary, upon sudden thaws may probably be sent up more forcibly, and so produce these fasciated stalks, whereas the natural and graduated ascent would have produced them but single." Prof. Hincks' explanation is, however, more near to the truth, and his opinion is borne out by the frequency with which this change is met with in certain plants which are frequently forced on during their growth, as lettuce, asparagus, endive, &c., all of which are very subject to this change. In the 'Transactions of the Horticultural Society of London,' vol. iv, p. 321, Mr. Knight gives an account of the cultivation of the cockscomb, so as to ensure the production of the very large flower-stalks for which this plant is admired. The principal points in the culture were the application of a large quantity of stimulating manure and the maintenance of a high temperature. One of them so grown measured eighteen inches in width.

The list which is appended is intended to show those plants in which fasciation has been most frequently observed. It makes no pretension to be complete, but is sufficiently so for the purpose indicated: the * denotes the especial frequency of the change in question; the ! indicates that the writer has himself seen the plant, so marked, affected in this way. The remainder have been copied from various sources.

Exogens.

a. Herbaceous.

• Ranunculus tripartitus.
  • *bulbosus!
  • Philonotis.
• Delphinium elatum.
  • *sp.!
• Hesperis matronalis.
• *Cheiranthus Cheiri!
• *Matthiola incana!
• *Brassica oleracea! var. pl. inflor.
• Linum usitatissimum!
• AlthÆa rosea!
• Lavatera trimestris.
• Geranii sp.
• TropÆolum majus!
• Viola odorata inflor.!
• Reseda odorata!
• Fragaria vesca.
• Ervum lens.
• Trifolium resupinatum.
  • repens!
  • pratense!
• Saxifraga mutata.
  • irrigua.
• Bupleurum falcatum.
• Bunium flexuosum.
• *Sedum reflexum!
  • cristatum!
• Epilobium augustifolium!
• Momordica Elaterium!
• Gaura biennis.
• Cotula foetida.
• Barkhausia taraxacifolia.
• Carlina vulgaris!
• Apargia autumnalis.
• *Leontodon Taraxacum inflor.!
• Centaurea Scabiosa.
• *Cichorium Intybus!
• Hieracium Pilosella.
  • aureum.
  • umbellatum.
• *Chrysanthemum Leucanthemum.
  • indicum!
• Anthemis nobilis.
  • arvensis.
• Cirsium lanceolatum.
• Conyza squarrosa!
• Inula dysenterica!
• Tragopogon porrifolium.
• Cnicus palustris.
• Carduus arvensis!
• Helianthus tuberosus!
  • annuus.
• Cineraria palustris.
• Helianthus sp.!
• Dahlia variabilis.
• Bellis perennis inflor.!
• Coreopsis sp.!
• Crepis virens.
• Lactuca sativa!
• Zinnia elegans.
• *Campanula medium!
  • rapunculoides.
  • thyrsoidea.
• Dipsacus pilosus.
  • fullonum.
  • silvestris.
• Knautia arvensis.
• Phyteuma orbiculare.
• Jasione montana.
• *Linaria purpurea!
• Antirrhinum majus!
• Veronica amethystea.
• Veronica maritima.
  • sp.
• Russellia juncea!
• Digitalis purpurea!
• Ajuga pyramidalis.
• Hyssopus officinalis.
• Dracocephalum moldavicum.
• Myosotis scorpioides.
• Echium pyrenaicum.
  • simplex.
• StapeliÆ sp.
• Lysimachia vulgaris!
• Androsace maxima.
• Primula veris inflor.!
  • denticulata inflor.!
• Polemonium coeruleum.
• Convolvulus sepium!
  • arvensis!
• Plantago media.
• *Euphorbia Characias.
  • exigua.
  • *Cyparissias.
• SuÆda maritima.
• *Celosia sp.
• Beta vulgaris inflor.!
• Phytolacca sp.

. Woody.

• Berberis vulgaris.
• Hibiscus syriacus!
• Acer pseudo-platanus!
• DodonÆa viscosa.
• Sterculia platanifolia.
• Euonymus japonicus!
• Vitis vinifera inflor.!
• Spartium Scoparium!
• Spartium junceum!
• Cytisus Laburnum.
  • nigricans.
• Chorozema ilicifolium.
• Amorpha sp.
• Phaseolus sp.
• Prunus sylvestris.
  • Laurocerasus!
• Rosa sp.!
• SpirÆa sp.!
• Cotoneaster microphylla!
• Ailanthus glandulosus.
• *Fraxinus Ornus!
  • *excelsior!
• Melia Azedarach.
• Xanthoxylum sp.!
• Sambucus nigra.!
• Aucuba japonica.
• Erica sp. cult.
• Jasminum nudiflorum!
  • officinale!
• Olea europoea.
• Punica Granatum.
• Ilex aquifolium!
• Daphne indica.
• Daphne odora.
• SuÆda fruticosa.
• Ulmus campestris.
• Alnus incana.
• Salix vitellina, &c.!
• Thuja orientalis.
• Pinus pinaster!
  • sylvestris!
• Abies excelsa!
• Taxus baccata.
• Larix europoea.

Endogens.

• Lilium Martagon.
  • candidum!
• *Fritillaria imperialis!
• Asparagus officinalis!
• Hyacinthus orientalis!
• Tamus communis!
• Narcissi sp.!
• Gladiolus sp.
• Zea Mays.
• Filices.

See also—Moquin-Tandon, 'Elem. Ter. Veget.,' p. 146; C. O. Weber, 'Verhandl. Nat. Hist.,' Vereins, f. d. Preuss., Rheinl. und Westphal., 1860, p. 347, tab. vii; Hallier, 'Phytopathol.,' p. 128; Boehmer, 'De plantis Fasciatis,' Wittenb., 1752.

Cohesion of foliar organs.—This takes place in several ways, and in very various degrees; the simplest case is that characterised by the cohesion of the margins of the same organ, as in the condition called perfoliate in descriptive works, and which is due either to a cohesion of the margins of the basal lobes of the leaf, or to the development of the leaf in a sheathing or tubular manner. As an abnormal occurrence, I have met with this perfoliation in a leaf of Goodenia ovata. The condition in question is often loosely confounded with connation, or the union of two leaves by their bases. In other cases the union takes place between the margins of two or more leaves.

Cohesion of margins of single organs.—The leaves of Hazels may often be found with their margins coherent at the base, so as to become peltate, while in other cases, the disc of the leaf is so depressed that a true pitcher is formed. This happens also in the Lime Tilia, in which genus pitcher- or hood-like leaves (folia cucullata) may frequently be met with. There are trees with leaves of this character in the cemetery of a Cistercian Monastery at Sedlitz, on which it is said that certain monks were once hung: hence the legend has arisen, that the peculiar form of the leaf was given in order to perpetuate the memory of the martyred monks. ('Bayer. Monogr. TiliÆ,' Berlin, 1861.) It is also stated that this condition is not perpetuated by grafting.

Fig. 8.—Pitcher-shaped leaf of Pelargonium.

I have in my possession a leaf of Antirrhinum majus, and also a specimen of Pelargonium, wherein the blade of the leaf is funnel-like, and the petiole is cylindrical, not compressed, and grooved on the upper surface, as is usually the case. A comparison of the leaves of Pelargonium peltatum with those of P. cucullatum ('Cav. Diss.,' tab., 106) will show how easy the passage is from a peltate to a tubular leaf. In these cases the tubular form may rather be due to dilatation than to cohesion. M. Kickx[16] mentions an instance of the kind in the leaves of a species of Nicotiana, and also figures the leaf of a rose in which two opposite leaflets presented themselves in the form of stalked cups. Schlechtendal[17] notices something of the same kind in the leaf of Amorpha fruticosa; Treviranus[18] in that of Aristolochia Sipho.

M. Puel[19] describes a leaf of Polygonatum multiflorum, the margins of which were so completely united together, as only to leave a circular aperture at the top, through which passed the ends of the leaves. The Rev. Mr. Hincks, at the meeting of the British Association at Newcastle (1838), showed a leaf of a Tulip, whose margins were so united that the whole leaf served as a hood, and was carried upwards by the growing flower like the calyptra of a Moss.

The margins of the stipules are also occasionally united, so as to form a little horn-shaped tube. I have met with instances of this kind in the common white clover, Trifolium repens, where on each side of the base of the petiole the stipules had the form just indicated. That the bracts also may assume this condition, may be inferred from the peculiar horn-like structures of Marcgraavia, which appear to originate from the union of the margins of the reflected leaf.

Tubular petals occur normally in some flowers, as Helleborus, Epimedium, Viola, &c., and as an exceptional occurrence I have seen them in Ranunculus repens, while in Eranthis hyemalis transitions may frequently be seen between the flat outer segments of the perianth and the tubular petals. To Dr. Sankey, of Sandywell Park, I am indebted for the flower of a Pelargonium, in which one of the petals had the form of a cup supported on a long stalk. This cup-shaped organ was placed at the back of the flower, and had the dark colour proper to the petals in that situation. I have seen a petal of Clarkia similarly tubular, while some of the cultivated varieties of Primula sinensis exhibit tubular petals so perfect in shape as closely to resemble perfect corollas.

Fig. 9.—Eranthis hyemalis. Transition from flat sepal to tubular petal.

Like the petals, the stamens, and even the styles, assume a hollow tubular form. This change of form in the case of the stamens is, of course, usually attended by the petaloid expansion of the filament, or anther, and the more or less complete obliteration of the pollen sacs, as in Fuchsias, and in some double-flowered Antirrhinums.[20] So also in some semi-double varieties of Narcissus poeticus, and in Aquilegia. By the late Professor Charles Morren, this affection of the stamens and pistils was called Solenaidie,[21] but as a similar condition exists in other organs, it hardly seems worth while to adopt a special term for the phenomenon, as it presents itself in one set of organs.

In many of these cases it is difficult to say whether the cup-like or tubular form is due to a dilatation or hollowing out of the organ affected, or to a fusion of its edges. The arrangement of the veins will in some cases supply the clue, and in others the regularity of form will indicate the nature of the malformation, for in those instances where the cup is the result of expansion, its margin is more likely to be regular and even than in those where the hollow form is the result of fusion.

Cohesion of several organs by their margins:—leaves, &c.—The union of the margins of two or more different organs is of more common occurrence than the preceding, the leaves being frequently subjected to this change. Occasionally, the leaflets of a compound leaf have been observed united by their margins, as in the strawberry, the white trefoil, and others. Sometimes the union takes place by means of the stalks only. I have an instance of this in a Pelargonium, in TropÆolum majus, and Strelitzia regina; in other cases, the whole extent of the leaf becomes joined to its neighbour, the leaves thus becoming completely united by their edges, as in those of Justicia, oxyphylla.[22] M. Clos[23] has observed the same thing in the leaves of the lentil Ervum lens, conjoined with fasciation of the stem, and many other examples might be given. Some of the recorded cases are probably really due to fission of one leaf into two rather than to fusion. Although usually the lower portions of the leaf are united together, leaving the upper parts more or less detached, there are some instances in which the margins of the leaf at their upper portion have been noticed to be coherent, while their lower portions, with their stalks, were completely free.[24]

Cohesion of the leaves frequently accompanies the union of the branches and fasciation as might have been anticipated. Moquin cites the fenestrated leaves of Dracontium pertusum, as well as some cases of a similar kind that are occasionally met with, as instances of the cohesion of the margins at the base and apex of the leaf, which thus appears perforated. This appearance, however, is probably due to some other cause. When the leaves are verticillate and numerous, and they become coherent by their margins, they form a foliaceous tube around the stem. When there are but two opposite leaves, and these become united by their margins, we have a state of things precisely resembling that to which the term connate is applied.

Fusion of the edges of the cotyledons also occasionally takes place, as in Ebenus cretica.[25] It has also been observed in Tithonia, and is of constant occurrence in the seed leaves of some Mesembryanthema. This condition must be carefully distinguished from the very similar appearance produced by quite a different cause, viz., the splitting of one cotyledon into two, which gives rise to the appearance as if two were partially united together.

Some of the ascidia or pitcher-like formations are due to the cohesion of the margins of two leaves, as in a specimen of Crassula arborescens, observed by C. Morren.

Fig. 10.—Two-leaved pitcher of Crassula arborescens, after C. Morren.

The stipules may also be fused together in different ways; their edges sometimes cohere between the leaf and the stem, and thus form a solitary intra-axillary stipule. At other times they become united in such a manner as to produce a single notched stipule opposite to the leaf. Again, in other cases, they are so united on each side of the stem, that in place of four there seem only to exist two, common to the two leaves as in the Hop.

To the Rev. M. J. Berkeley I am indebted for specimens of a curious pitcher-like formation in the garden Pea. The structure in question consisted of a stalked foliaceous cup proceeding from the inflorescence. On examination of the ordinary inflorescence, there will be seen at the base of the upper of two flowers a small rudimentary bract, having a swollen circular or ring-like base, from which proceeds a small awl-shaped process, representing the midrib of an abortive leaf. In some of Mr. Berkeley's specimens, the stipules were developed as leafy appendages at the base of the leaf-stalk or midrib, the latter retaining its shortened form, while, in others, the two stipules had become connate into a cup, and all trace of the midrib was lost. The cup in question would thus seem to have been formed from the connation of two stipules which are ordinarily abortive.

Cohesion of the bracts by their edges, so as to form a tubular involucre, or by their surfaces, so as to form a cupule, is not of uncommon occurrence, under natural conditions, and may be met with in plants which ordinarily do not exhibit this appearance.

Cohesion of the sepals in a normally polypetalous calyx renders the latter gamosepalous, and is not of uncommon occurrence, to a partial extent, though rarely met with complete. I have observed a junction of the sepals to be one of the commonest malformations among Orchids, indeed such a state of things occurs normally in Masdevallia Cypripedium, &c. An illustration of this occurrence is given by Mr. J. T. Moggridge in Ophrys insectifera, in 'Seemann's Journal of Botany,' 1866, p. 168, tab. 47. In Orchids, this cohesion of sepals is very often co-existent with other more important changes, such as absence of the labellum, dislocation of the parts of the flower, &c.

Fig. 11.—Gamopetalous flower of Papaver bracteatum.

Cohesion of the petals.—LinnÆus mentions the occurrence of cohesion of the petals in Saponaria.[26] Moquin notices a Rose in which the petals were united into a long tube, their upper portions were free and bent downwards, forming a sort of irregular limb. An instance of the polypetalous regular perianth of Clematis viticella being changed into a monopetalous irregular one, like the corolla of Labiates, is recorded by Jaeger.[27] There is in cultivation a variety of Papaver bracteatum, in which the petals are united by their margins so as to form a large cup. Under normal circumstances, the petals become fused together by their edges along their whole extent, at the base only, at the apex only, as in the Vine, or at the base and apex, leaving the central portions detached. Indications of the junction of the petals may generally be traced by the arrangement of the veins, or by the notches or lobes left by imperfect union. In Crocuses I have frequently met with cohesion of the segments of the perianth, by means of their surfaces, but the union was confined to the centre of the segment, leaving the rest of the surfaces free.

Cohesion of the stamens.—Under natural circumstances, cohesion of the stamens is said to take place either by the union of their filaments, so as to form one, two, or more parcels (Monadelphia, Diadelphia, Polyadelphia); at other times, by the cohesion of the anthers (Syngenesia), in which latter case the union is generally very slight. It must be remembered, however, that the so-called cohesion of the filaments is in many cases due rather to the formation of compound stamens, i.e. to the formation from one original staminal tubercle of numerous secondary ones, so that the process is rather one of over development than of fusion or of disjunction. These conditions may be met with as accidental occurrences in plants or in flowers, not usually showing this arrangement. Thus, for instance, Professor Andersson, of Stockholm, describes a monstrosity of Salix calyculata, in which the stamens were so united together as to form a tube open at the top like a follicle.[28] This is an exaggerated degree of that fusion which exists normally in Salix monandra, in Cucurbits and other plants.

Cohesion of the pistils is also of very frequent occurrence in plants, under ordinary circumstances, but is less commonly met with than might have been expected as a teratological phenomenon.

Further details relating to cohesion of the various parts of the flower are cited in Moquin-Tandon, 'El. Ter. Veg.,' p. 248; 'Weber. Verhandl. Nat. Hist. Vereins f. d. Preuss. Rheinl. und Westphal.,' 1860, p. 332, tabs. 6 et 7.

Formation of ascidia or pitchers.—In the preceding paragraphs, the formation of tubular or horn-like structures, from the union of the margins of one organ, or from the coalescence, or it may be from the want of separation of various organs, has been alluded to, so that it seems only necessary now, by way of summary, to mention the classification of ascidia proposed by Professor Charles Morren[29], who divides the structures in question into two heads, according as they are formed from one or more leaves. The following list is arranged according to the views of the Belgian savant, and comprises a few additional illustrations. Those to which the ! is affixed have been seen by the writer himself; the * indicates the more frequent occurrence of the phenomenon in some than in other plants. Those plants, such as Nepenthes, &c., which occur normally and constantly, are not here included. Possibly some of the cases would be more properly classed under dilatation or excavation.

Ascidia.

A. Monophyllous.

1. Sarracenia-like pitchers, formed by a single leaf, the edges of which are united for the greater portion of their length, but are disunited near the top, so as to leave an oblique aperture.

• *Brassica oleracea (several of the cultivated varieties)!
• *Tilia europÆa!
• Pelargonium inquinans!
• Staphylea pinnata.
• Amorpha fruticosa.
• Pisum sativum!
• Lathyrus tuberosus.
• Vicia sp.
• Gleditschia sp.
• Ceratonia siliqua.
• Trifolium repens!
• Cassia marylandica.
• Mimosa Lophantha.
• Rosa centifolia.
  • gallica.
• Begonia sp.
• Bellis perennis!
• Nicotiana sp.
• Goodenia ovata!
• Antirrhinum majus!
• Vinca rosea.
• Polygonum orientale.
• Aristolochia sipho?
• CodiÆum variegatum var.!
• Spinacia oleracea.
• Corylus avellana!
• Polygonatum multiflorum.
• Xanthosoma appendiculatum!

2. Calyptriform or hood-like pitchers, formed by the complete union of the margins, and falling off by a transverse fissure (as in the calyx of Escholtzia).

• Tulipa Gesneriana.

B. Polyphyllous.

1. Diphyllous, formed by the union of two leaves into a single cup, tube, or funnel, &c.

• Pisum sativum (stipules)!
• Crassula arborescens.
• Polygonatum multiflorum.

2. Triphyllous, formed by the union of three leaves.

• Paris quadrifolia var.

Besides the above varieties of ascidia formed from the union of one or more leaves, there are others which seem to be the result of a peculiar excrescence or hypertrophy of the leaf. Such are some of the curious pitcher-like structures met with occasionally in the leaves of cabbages, lettuces, Aristolochia, &c. See Hypertrophy, cup-like deformities, &c.

In addition to other publications previously mentioned, reference may be made to the following treatises on the subject of ascidia:—Bonnet, 'Rech. Us. Feuilles,' p. 216, tab. xxvi, f. 1, Brassica; De Candolle, 'Trans. Hort. Soc.,' t. v, pl. 1, Brassica; Id., 'Org. Veget.,' I, 316; 'Bull. Soc. Bot. Fr.,' I, p. 62, Polygonatum; 'Bull. Acad. Belg.,' 1851, p. 591, Rosa; Hoffmann, 'Tijdschrift v. Natuur. Geschied.,' vol. viii, p. 318, tab. 9, Ceratonia; C. Mulder, 'Tijdschrift, &c.,' vol. vi, p. 106, tab. 5, 6, Trifolium, Mimosa, Staphylea;' Molkenboer,' p. 115, t. 4, Brassica.

FOOTNOTES:

[10] See a curious instance of this kind in the branches of Pinus. 'Regel. Garten Flora,' vol. 8, tab. 268.

[11] 'Bull. Soc. Bot. France,' 1860, p. 881.

[12] Ibid., 1861, p. 708.

[13] Ibid., 1860, p. 923.

[14] 'Proc. Linn. Soc.,' April 5, 1853.

[15] 'Organ. VÉgÉt.,' pl. iii, fig. 1.

[16] 'Bull. Acad. Roy. Bruxelles,' t. xviii, p. i and p. 591.

[17] 'LinnÆa,' tom. 13, p. 383.

[18] 'Verhandl. Nat. Hist. Vereins,' 1859, Bonn, tom. xvi, tab. 3.

[19] 'Bull. Soc. Bot. Fr.,' vol. i, p. 62.

[20] 'Report of Internat. Bot. Congress,' London, 1866, p. 131, tab. vii, figs. 10–13.

[21] 'Bull. Acad. Roy. Belg.,' t. xviii, 2nd part, p. 179.

[22] D. C., 'Organ. VÉgÉt.,' pl. xvii, fig. 3, and pl. xlviii, fig. 2.

[23] 'MÉm. Acad. Toulouse,' 1862.

[24] Bonnet, 'Recherches Us. feuill.,' pl. xxi, fig. 2.

[25] De Candolle, 'MÉm. LÉg.,' pl. v, fig. 14.

[26] 'Phil. Bot.,' § 125.

[27] 'Nov. Act. Acad. Nat. Cur.,' 14, p. 642, t. xxxvii.

[28] 'Journal of the Linn. Soc. Bot.,' vol. iv, p. 55.

[29] 'Bull. Acad. Roy. Bruxelles,' 1838, t. v, p. 582. 'Bull. Acad. Roy. Belg.,' 1852, t. xix, part iii, p. 437.

CHAPTER II.
ADHESION.

Adhesion, so called, occurs either from actual union of originally distinct members of different whorls or from the non-occurrence of that separation which usually takes place between them. It is thus in some degree a graver deviation than cohesion, and is generally a consequence of, or at least is coexistent with, more serious changes; thus if two leaves of the same whorl are coherent the change is not very great, but if two leaves belonging to different whorls, or two leaves in the same spiral cycle are adherent, a deformation in the axis or a certain amount of dislocation must almost necessarily exist. Adhesion as a normal occurrence is usually the result of a lack of separation rather than of union of parts primitively separate. Instances of adhesion between different organs is seen under ordinary circumstances in the bract of the Lime tree, which adheres to the peduncle, also in Neuropeltis, while in Erythrochiton hypophyllanthus the cymose peduncles are adherent to the under surface of the leaf.

Adhesion between the axes of the same plant is sufficiently treated of under the head of Cohesion, from which it is in this instance impossible to make a distinction. Adhesion of the inflorescence is necessarily a frequent accompaniment of fasciation and cohesion of the branches.

Adhesion of foliar organs may occur either between the margins or between the surfaces of the affected parts; in the former case there is almost necessarily more or less displacement and change of direction, such as a twisting of the stem and a vertical rather than a horizontal attachment of the foliar organ to it; hence it generally forms but a part of other and more important deviations.

Adhesion of leaves by their surfaces.—The union of leaves by their surfaces is not of very frequent occurrence, many of the instances cited being truly referable to other conditions. Bonnet describes the union of two lettuce leaves, and Turpin that of two leaves of Agave americana, in which latter the upper surface of one leaf was adherent to the lower surface of the leaf next above it, and I have myself met with similar instances in the wallflower and in lettuce and cabbage leaves; other instances have been mentioned in Saxifraga, Gesnera, &c.[30]

In these cases, owing to the non-development of the internodes, the nascent leaves are closely packed, and the conditions for adhesion are favorable, but in most of the so-called cases of adhesion of leaf to leaf by the surface, a preferable explanation is afforded either by an exuberant development (hypertrophy) or by chorisis (see sections on those subjects). Thus, when a leaf of this kind is apparently so united, that the lower surface of one is adherent to the corresponding surface of another, the phenomenon is probably due rather to extra development or to fission. There is an exception to this, however, in the case of two vertically-erect leaves on opposite sides of the stem; here the two upper or inner surfaces may become adherent, as in an orange, where two leaves were thus united, the terminal bud between them being suppressed or abortive.

Adhesion between the membranous bract of Narcissus poeticus and the upper surface of the leaf is described by Moquin.[31] The same author mentions having seen a remarkable example of adhesion in the involucels of Caucalis leptophylla, the bracts of which were soldered to the outer surface of the flowers. M. Bureau[32] mentions an instance wherein the spathe of Narcissus biflorus was partially twisted in such a manner that the lower surface of its median nerve was adherent to the corresponding surface of one of the sepals, mid-rib to mid-rib, thus apparently confirming a law of G. de Hilaire, that when two parts of the same individual unite, they generally do so by the corresponding surfaces or edges, but the rule is probably not so general in its application as has been supposed.

Adhesion of foliar to axile organs.—The appendicular organs may likewise be found united to the axile ones. This union takes place in many ways; sometimes the leaves do not become detached from the stem for a considerable distance, as in the so-called decurrent leaves, at other times the leaves are prolonged at their base into lobes, which are directed along the stem, and are united with it. Turpin records a tendril of a vine which was fused with the stem for some distance, and bore leaves and other tendrils. Union of the leaf or bract with the flower-stalk is not uncommon. It occurs normally in the Lime and other plants.

Adhesion of the sepals to the petals is spoken of by Morren as calyphyomy, ?a??? f??a?.[33] Moquin cites an instance in Geranium nodosum, in which one petal was united by its lower surface to one of the segments of the calyx. A similar circumstance has been observed in Petunia violacea by Morren. Duchartre describes an instance wherein one of the outer sepals of Cattleya Forbesii was adherent to the labellum.[34]

Adhesion of the stamens to the petals is of common occurrence under natural circumstances. Cassini has described a malformation of Centaurea collina, in which two of the five stamens were completely grafted with the corolla, the three others remaining perfectly free. Adhesion of the petals to the column is not of infrequent occurrence among Orchids. I have observed cases of the adhesion of the segments of the perianth to the stamen in Ophrys aranifera, Odontoglossum, sp. &c. It is the ordinary condition in Gongora and some other genera. I have seen it also in Lilium lancifolium. Some forms of Crocus, occasionally met with, present a very singular appearance, owing to the adhesion of the stamens to the outer segments of the perianth, the former, moreover, being partially petaloid in aspect. M. de la Vaud[35] speaks of a similar union in Tigridia pavonia. Morren[36] describes a malformation of Fuchsia wherein the petals were so completely adherent to the stamens, that the former were dragged out of their ordinary position, so as to become opposite to the sepals; the fusion was here so complete that, no trace of it could be seen externally. It should be remarked that it was the outer series of stamens that were thus fused.[37]

Fig. 12.—Crocus. Adhesion of petaloid stamens to perianth.

Adhesion of stamens to pistils.—The stamens also may be united to the pistils, as in gynandrous plants. Moquin speaks of such a case in a Scabious; M. Clos in Verbascum australe.[38] I have seen cases of the same kind in the Wallflower, Cowslip (Primula veris), Tulip, Orange, in the garden Azalea and other plants.

Miscellaneous adhesions.—Sometimes organs, comparatively speaking, widely separated one from the other, become united together. Miquel has recorded the union of a stigma with the middle lobe of the lower lip of the corolla of Salvia pratensis.[39] In the accompanying figure [fig. 13], taken from a double wallflower, there is shown an adhesion between a petal and an open carpel on the one side, and a stamen on the other.

Moquin speaks of some pears, which were united, at an early stage, with one or two small leaves borne by the peduncle and grafted to the fruit by the whole of their upper surface. As the pear increased in size the leaves became detached from it, leaving on the surface of the fruit an impression of the same form as the leaf, and differing in colour from the rest of the surface of the fruit. Traces of the principal nerves were seen on the pear.

Fig. 13.—Cheiranthus cheiri. Adhesion of petal to stamen and open carpel.

It is curious to notice how very rare it is for the calyx to adhere to the ovary in flowers where that organ is normally superior. The "calyx inferus" seems scarcely ever to become "calyx superus," while, on the other hand, the "calyx normaliter superus" frequently becomes inferior from detachment from, or from want of union with the surface of the ovary.

Adhesion of fruit to branch.—Of this Mr. Berkeley[40] cites an instance in a vegetable marrow (Cucumis), where a female flower had become confluent with the branch, at whose base it was placed, and also with two or more flowers at the upper part of the same branch, so as to make an oblique scar running down from the apex of the fruit to the branch.

Synanthy.—Adhesion of two or more flowers takes place in various ways; sometimes merely the stalks are united together, so that we have a single peduncle, bearing at its extremity two flowers placed in approximation very slightly adherent one to the other. In this manner I have seen three flowers of the vegetable marrow on a common stalk, the flowers themselves being only united at the extreme base. Occasionally cases may be met with wherein the pedicels of a stalked flower become adherent to the side of a sessile flower. I have noticed this commonly in UmbelliferÆ. Union of this kind occurs frequently in the common cornel (Cornus), wherein one of the lower flowers becomes adherent to one of the upper ones. In De Candolle's 'Organographie VÉgÉtale,' Plates 14 and 15, are figured cases of fusion of the flower stems of the Hyacinth and of a Centaurea. In other cases the union involves not only the stalk but the flowers themselves; thus fusion of the flowers is a common accompaniment of fasciation, as was the case in the Campanula figured in the cut (fig. 14).

Fig. 14.—Synanthic flowers of Campanula medium.

Synanthy may take place without much derangement of the structure of either flower, or the union may be attended with abortion or suppression of some of the parts of one or both flowers. Occasionally this union is carried to such an extent that a bloom appears to be single, when it is, in reality, composed of two or more, the parts of which have become not only fused, but, as it were, thrust into and completely incorporated one with another, and in such a manner as to occupy the place of some parts of the flower which have been suppressed. It must not be overlooked that this adhesion of one flower to another is a very common occurrence under natural circumstances, as in Lonicera, in the common tomato, in Pomax, Opercularia, Symphyomyrtus, &c., while the large size of some of the cultivated sunflowers is in like manner due to the union of two or more flower-heads.

One of the simplest instances of synanthy is that mentioned by M. Duchartre,[41] in which two flowers of a hyacinth were united together simply by means of two segments of the perianth one from each flower. A similar occurrence has been cited by M. Gay in Narcissus chrysanthus. In like manner the blossoms of Fuchsias or Loniceras occasionally become adherent merely by their surface, without involving any other change in the conformation of the flowers. M. Maugin alludes to a case of this kind in Aristolochia Clematitis.[42]

But it is more usual for some of the organs to be suppressed, so that the number of existing parts is less than would be the case in two or more uncombined flowers. A few illustrations will exemplify this. In two flowers of Matthiola incana, that I observed to be joined together, there were eight sepals, eight petals, and ten perfect stamens, eight long and two short, instead of twelve. Closer examination showed that the point of union between the two flowers occurred just where, under ordinary circumstances, the two short stamens would be. In this instance but little suppression had occurred. In similar flowers of Narcissus incomparabilis I remarked a ten-parted perianth, ten stamens within a single cup, two styles, and a five-celled ovary. Here, then, it would appear that two segments of the perianth, two stamens, and one carpel were suppressed. In a Polyanthus there were nine sepals, nine petals, nine stamens, and a double ovary.

Fig. 15.—Union of three flowers of Calanthe vestita.

Fig. 16.—Shows the abortion of the central spur in synanthic flowers of Calanthe vestita.

As an illustration of a more complicated nature reference may be made to three flowers of Aconitum Napellus, figured by A. de Chamisso, 'LinnÆa,' vol. vii, 1832, p. 205, tab. vii, figs. 1, 2. In this specimen the two outer blossoms had each four sepals present, namely, the upper hooded one, one of the lateral sepals, and both of the inferior ones; the central flower had only the upper sepal and one other, probably one of the lower sepals; thus there were but ten sepals instead of fifteen. The nectary-like petals, the stamens, and pistils were all present in the lateral flowers, but were completely suppressed in the middle one. A less degree of suppression was exemplified in a triple flower of Calanthe vestita sent me by Dr. Moore, of Glasnevin, in which all the parts usually existing in three separate flowers were to be found, with the exception of the spur belonging to the labellum of the middle flower (figs. 15, 16).

One of the most common malformations in the Foxglove (Digitalis) results from the fusion of several of the terminal flowers into one. In these cases the number of parts is very variable in different instances; the sepals are more or less blended together, and the corollas as well as the stamens are usually free and distinct, the latter often of equal length, so that the blossom, although truly complex, is, as to its external form, less irregular than under natural circumstances. The centre of these flowers is occupied by a two to five-celled pistil, between the carpels of which, not unfrequently, the stem of the plant projects, bearing on its sides bracts and rudimentary flowers. (See Prolification.) An instance of this nature is figured in the 'Gardeners' Chronicle,' 1850, p. 435, from which the cut (fig. 17) is borrowed.

Fig. 17.—Synanthy and other changes in a Foxglove.

One of the most singular recorded instances of changes connected with fusion of the flowers is that cited by Reinsch,[43] where two female flowers of Salix cinerea were so united with a male one as to produce an hermaphrodite blossom.

It follows, from what has been said, that the number of parts that are met with in these fused flowers varies according to the number of blossoms and of the organs which have been suppressed. Comparatively rarely do we find all the organs present; but when two flowers are united together we find every possible variety between the number of parts naturally belonging to the two flowers and that belonging to a single one. Sometimes instances are met with wherein the calyx does not present the normal number of parts, while the other parts of the flower are in excess. I have seen in a Calceolaria a single calyx, with the ordinary number of sepals, enclosing two corollas, adherent simply by their upper lips, and containing stamens and pistils in the usual way. In this instance, then, the sepals of one flower must have been suppressed, while no such suppression took place in the other parts of the flower.

Professor Charles Morren paid special attention to the various methods in which the flowers of Calceolarias may become fused, and to the complications that ensue from the suppression of some parts, the complete amalgamation of others, &c. Referring the reader to the Belgian savant's papers for the full details of the changes observed, it is only necessary to allude to a few of the most salient features.

Fig. 18.—Synanthic flowers of Calceolaria in which, with two upper lips, there was but a single lower one.

Sometimes the upper lips of two flowers are fused into one, the two lower remaining distinct. In other cases, the upper lip disappears altogether, while there are two lower lips placed opposite one another;, of the stamens, sometimes the outermost, at other times the innermost disappear.[44]

Occasionally there appears to be, as it were, a transference of the parts of one flower to another. One of the simplest and most intelligible cases of this kind is recorded by Wigand in the 'Flora' for 1856, in a compound flower of Polygonatum anceps, in which within a twelve-parted perianth there were twelve stamens and two pistils, one four-celled, the other two-celled; hence it would appear as if a carpel belonging to one flower had become united to those constituting the pistil of the adjacent one. Among Orchids this fusion of some of the elements of different flowers, together with the suppression of others, is carried to such an extent as to render the real structure difficult to decipher. Sometimes flowers of Ophrys aranifera, at first sight seeming normal as to the number, and almost so as regards the arrangement of their parts, have yet, on examination, proved to be the result of a confluence of two flowers. Mr. Moggridge has observed similar phenomena in the same species at Mentone.

Sometimes the fusion affects flowers belonging to different branches of the same inflorescence, as in Centranthus ruber, described by Buchenau, 'Flora,' 1857, p. 293, and even a blossom of one generation of axes may be united with a flower belonging to another generation. Thus M. Michalet[45] speaks of a case wherein the terminal flower of Betonica alopecuros was affected with Peloria, and fused with an adjacent one belonging to a secondary axis of inflorescence, and not yet expanded. This latter flower had no calyx, but in its place were three bracts, surrounding the corolla; this again was united to the calyx of the terminal bloom in a most singular manner, the limb of the corolla and that of the calyx being so joined one to the other as to form but a single tube. It is not uncommon, as has been before stated, to find two corollas enclosed within one calyx, but this is probably the only recorded instance of the fusion of the calyx and corolla of two different flowers belonging to two different axes.

From the preceding details, as well as from others which it is not necessary to give in this place, it would appear that synanthy is more liable to occur where the flowers are naturally crowded together[46] than where they are remote; so too, the upper or younger portions of the inflorescence are those most subject to this change. In like manner the derangements consequent on the coalescence of flowers are often more grave in the central organs, which are most exposed to pressure, and have the least opportunities of resisting the effects of that agency, than they are in the outer portions of the flowers where growth is less restricted.

Morren in his papers on synanthic Calceolarias, before referred to, considers that the direction in which fusion acts is centripetal, e.g. from the circumference towards the centre of the flower, thus reversing the natural order of things. He considers that there is a radical antagonism between the normal organizing forces and the teratological disorganizing forces, and explains in this way the frequent sterility of monsters from an imperfect formation of stamens, or pistils, or both.

The greater tendency in synanthic flowers of parts of one whorl to adhere to the corresponding organs in another flower has often been remarked, though the dislocation of parts may be so great as to prevent this from being carried out in all cases. It appears also that synanthy is more frequently met with among flowers which have an inferior ovary than in those in which the relative position of the organ in question is reversed. This remark applies particularly to individual cases; the proportion as regards the genera may not be so large. The explanation of this must of course depend on the circumstances of each particular case; and it would be wrong to attempt to lay down a general rule, when organogenists have not yet fully decided in what plants the inferior ovary is an axial structure, and in what others the appearance is due to the adhesion of the base of the calyx to the carpels.

The list which follows is not intended as a complete one, but it may serve to show what plants are more particularly subject to this anomaly; the * indicates unusual frequency of occurrence, the ! signifies that the writer has himself seen instances in the plants named. Many of the recorded cases of Synanthy are really cases of adhesion of the inflorescence rather than of the flowers.

• Ranunculus Lingua.
  • bulbosus!
• Aconitum Napellus.
• Delphinium sp.!
• Matthiola incana!
• Arabis sagittata.
• Silene sp.
• Reseda odorata!
• Vitis vinifera.
• Citrus aurantium.
• *Fuchsia var. hort.!
• Œnothera sp.
• Saxifraga sp.
• Podalyria myrtillifolia.
• Prunus Armeniaca.
  • spinosa.
• Pyrus Malus.
• Persica vulgaris.
• CratÆgus monogyna.
• Robinia pseudacacia.
• Gleditschia triacanthos.
• Syringa persica.
• Cornus sanguinea.
• Viburnum sp.
• *Lonicera sp. plur!
• Centranthus ruber!
• Valantia cruciata.
• Centaurea moschata.
  • Jacea.
• Zinnia elegans.
• Zinnia revoluta.
• Helianthus sp.!
• Spilanthes oleracea.
• Dahlia.
• *Leontodon Taraxacum!
• Senecio Doria.
• Cichorium Intybus.
• Lactuca sativa.
• Anthemis retusa.
• *Campanula medium!
  • persicifolia.
• Azalea indica!
• Vinca minor.
• Atropa Belladonna.
• *Solanum Lycopersicum!
• *Petunia violacea!
• Galeopsis ochroleuca.
• Betonica alopecuros.
• *Digitalis purpurea!
• *Antirrhinum majus!
• *Linaria purpurea!
• *Pedicularis sylvatica!
• *Calceolaria var. hort.!
• Scrophularia nodosa.
• Salpiglossis straminea.
• Streptocarpus Rexii.
• *Gesnera var. hort.!
• Æschynanthus sp.!
• Thyrsacanthus rutilans!
• Anagallis collina.
• *Primula veris!
  • Auricula.
• *Primula acaulis, var. umbellata!
  • elatior?
  • *sinensis!
• Aristolochia Clematitis.
• Blitum sp.
• Chenopodium sp.
• Rumex sp.
• Salix cinerea.
• *Hyacinthus orientalis!
• Lilium bulbiferum!
  • croceum, et sp. alix, pl.
• Tulipa, sp.
• Polygonatum anceps.
• Fritillaria imperalis!
• Agave americana.
• Iris versicolor.
  • sambucina.
• Crocus, sp.
• Colchicum autumnale.
• Narcissus incomparabilis!
  • Tazetta.
  • biflorus.
  • chrysanthus.
• *Ophrys aranifera!
• Calanthe vestita!
• Oncidium bicolor.
  • ornithorhyncum.
  • &c. &c.

In addition to the works before cited, additional information on this subject may be gained from the following:—Jaeger, 'Missbilld.,' p. 92. v. Schlechtend, 'Bot. Zeit.,' 1856, Robinia. Weber, 'Verhandl. Nat. Hist. Vereins. Preuss. Rheinl.,' 1849, p. 290, Primula. Hincks, 'Rep. Brit. Assoc. Newcastle,' 1838, Salpiglossis. Clos, 'MÉm. Acad. Toulouse,' vol. vi, 1862, Anagallis. Wigand, 'Flora,' 1856, tab. 8, Pedicularis. Henfrey, 'Botan. Gazette,' i, p. 280, Reseda. P. Reinsch, 'Flora,' 1860, tab. 7, Petasites. Weber, Verhandl. Nat. Hist. Vereins. f.d. Preuss. Rheinl. u. Westphal.,' 1860, p. 332, tabs. 6 et 7, Prunus, Persica, Campanula, Taraxacum, Saxifraga, Silene, Hyacinthus, &c. Miquel, 'LinnÆa,' xi, p. 423, Colchicum. Michel, 'TraitÉ du Citronnier,' tab. 6, Citrus.

Syncarpy.—In the preceding section it has been shown that the carpels, like other parts of the flower, are subject to be united together. This union may either take place between the carpels of a single flower or between the pistils of different flowers. In the latter case the other floral whorls are generally more or less altered. Where, however, the ovary is, as it is called, inferior, it may happen that the pistils of different flowers may coalesce more or less without much alteration in the other parts of the flower, as happens normally in many CaprifoliaceÆ, RubiaceÆ, &c. &c. In some of these cases it must be remembered that the real structure of the apparent fruit is not made out beyond dispute, the main points of controversy being as to what, if any, share the dilated fruit-stalk or axis takes in the formation of such organs. Again, it will be borne in mind that in some cases the so-called fruit is made up of a number of flowers all fused together, as in the Mulberry or the Pineapple, in which plants what is, in ordinary language, called the fruit really consists of the whole mass of flowers constituting the inflorescence fused together. Union of the fruits may also in some cases take place between the carpels after the fall of the other floral whorls, particularly when the outer layers of the pericarp assume a succulent condition, so that under the general head of syncarpy really different conditions are almost necessarily grouped together, and, in seeking to investigate the causes of the phenomenon, the particular circumstances of each individual case must be taken into account. Syncarpy takes place in various degrees; sometimes only the stalks are joined; at other times the whole extent of the fruit, as in cherries, &c. This peculiarity did not escape the observant mind of Shakespeare—

"A double cherry seeming parted.

But yet a union in partition,

Two lovely berries moulded on one stem."

'Midsummer Night's Dream,' act iii, sc. 2.

A similar union has been observed in peaches, gooseberries, gourds, melons, and a great many other fruits. In the Barbarossa grape I have frequently seen a fusion of two, three, four or more berries quite at the end of the bunch, so that the clusters were terminated by a compound grape. Seringe has remarked sometimes two, sometimes three, fruits of Ranunculus tripartitus soldered together. He has also seen three melons similarly joined.[47] Turpin mentions having seen a complete union between the three smooth and leathery pericarps which are naturally separate and enclosed within the spiny cupule of the chestnut.[48] Poiteau and Turpin have figured and described in their treatise on fruit trees, under the name of NÉfle de Correa, four or five medlars, joined together and surmounted by all the persistent leaflets of the calyces.[49]A very remarkable example of Syncarpy has been recorded by E. Koenig in which nine strawberries were borne on one stem (Fragaria botryformis),[50] and a similar malformation has been observed in the Pineapple.

When two fruits are united together they may be of about equal size, while in other cases one of the two is much smaller than the other. This was the case in two cucumbers given to me by Mr. James Salter. These were united together along their whole length excepting at the very tips; the upper one of the two was much larger than the lower, and contained three cells, the lower fruit was one-celled by suppression. Both fruits were curved, the curvature being evidently due to the more rapid growth of the upper as compared with the lower one.

Fig. 19.—Adhesion of two apples.

Fig. 20.—Section of united apples.

In many of these cases, where the fruits are united by their bases, the summits become separated one from the other, so as to resemble the letter V. Such divergence is of frequent occurrence where fruits are united by their stalks, because, as growth goes on, the tendency must necessarily be towards separation and divergence of the tips of the fruit.

In some cases of Syncarpy the fusion and interpenetration of the carpels is carried to such an extent that it is very difficult to trace on the outer surface the lines of union. The fruit in these cases resembles a single one of much larger size than usual. Moquin mentions a double apple in which the connection was so close that the fruit was not very different in form from what is customary, and a similar thing happens with the tomato. In the case of stone-fruits it sometimes happens, not only that the outer portions are adherent, but that the stones are so likewise.

M. Roeper has observed two apples grafted together, one of which had its stalk broken, and seemed evidently borne and nourished by the other apple;[51] and a similar occurrence happens not infrequently in the cucumber. Moquin has seen three united cherries having only a single stalk jointed to the central fruit, the lateral cherries having each a slight depression or cicatrix marking the situation of the suppressed stalks. Schlotterbec has figured three apples presenting precisely similar appearances.[52]

Fusion of two or more nuts (Corylus) is not uncommon; I have seen as many as five so united.[53] In these cases the fruits may be united together in a ring or in linear series.

In some LeguminosÆ, contrary to the general rule in the order, more than one carpel is found; thus peas, French beans, and other similar plants, are occasionally met with having two or more pods within the same calyx, and in Gleditschia triacanthos and CÆsalpinia digyna this is so commonly the case as to be considered almost the normal state. (De Cand. 'Mem. Leg.,' pl. 2, fig. 6; pl. 3, fig. 2.) At times these carpels become fused together, and it becomes difficult, when the traces of the flower have disappeared, to ascertain whether these carpels were formed in one flower, or whether they were the result of the fusion of several blossoms. I have seen an instance of this kind in a plum in which there were two carpels in the same flower, the one being partially fused to the other. The nature of such cases may usually be determined by an inspection of the peduncle which shows no traces of fusion. (See chapter on Multiplication.)

When, however, the fruits are sessile, and they become grafted together, the kind of syncarpy is difficult to distinguish. It, may, nevertheless, be said as a general rule that the union brought about by the approximation of two fruits, after the fall of the floral whorls, is never so complete or so intimate as that determined by synanthy; and also that in those cases where there are supernumerary carpels in the flower, and those carpels become united together, they are rarely so completely fused that their individuality is lost.

An analogous phenomenon takes place not uncommonly in mosses, the spore capsules of which become united together in various ways and degrees. Schimper[54] cites the following species as subject to this anomaly:—Buxbaumia indusiata, Leskea sericea, Hypnum lutescens, Anomodon alternatus, Clinacium dendroides, Bryum cÆspititium, Brachythecium plumosum, Mnium serratum, Splachnum vasculosum. It has also been observed in Trichostomum rigidulum and Hypnum triquetrum.

In addition to the authorities already mentioned, the reader may consult Moquin-Tandon, 'El. Ter. Veg.,' p. 270. Turpin. 'MÉm. greffe. Ann. Sc. Nat.,' ser. i, t. xxiv, p. 334. De Candolle, 'Organ. Veget.,' t. i. Duhamel, 'Phys. des Arbres,' t. i, p. 304, tab. xiii, xiv. Weber. 'Verhandl. Nat. Hist. Vereina f. d. Preuss. Rheinl. u. Westphal.,' 1860, p. 332, tab. vi. et vii.

Synspermy, or Union of the Seeds.—Seeds may be united together in various degrees, either by their integuments,[55] or by their inner parts. Such union of the seeds, however, is of rare occurrence. It takes place normally, to a slight extent, in certain cultivated forms of cotton, wherein the seeds are aggregated together into a reniform mass, whence the term kidney cotton. Union of the parts of the embryo is treated under another head (see Synophty).

Adhesion between the axes of different plants.—Under this head may be classed the union that takes place between the stems, branches, or roots of different plants of the same species, and that which occurs between individuals of different species; the first is not very different in its nature from cohesion of the branches of the same plant (figs. 21, 22). It finds its parallel, under natural circumstances, among the lower cryptogams, in which it often happens that several individual plants, originally distinct, become inseparably blended together into one mass. In the gardening operations of inarching, and to some extent in budding, this adhesion of axis to axis occurs, the union taking place the more readily in proportion as the contact between the younger growing portions of the two axes respectively is close. The huge size of some trees has been, in some cases, attributed to the adnation of different stems. This is said to be the case with the famous plane trees of Bujukdere, near Constantinople, and in which nine trunks are more or less united together.[56]

Fig. 21.—Adhesion of two distinct stems of oak, or possibly cohesion of branches of the same tree. 'Gard. Chron.,' 1846, p. 252.

A similar anastomosis may take place in the roots. Lindley cites a case wherein two carrots, of the white Belgian and the red Surrey varieties respectively, had grown so close to each other that each twisted half round the other, so that they ultimately became soldered together; the most singular thing with reference to this union was, that the red carrot (fig. 23, b), with its small overgrown part above the junction, took the colour and large dimensions of the white Belgian (d), which, in like manner, with its larger head above the joining (a), took the colour and small dimensions of the red one at and below the union (e d). The respective qualities of the two roots were thus transposed, while the upper portions or crowns were unaffected: the root of one, naturally weak, became distended and enlarged by the abundant matter poured into it by its new crown; and in like manner the root of the other, naturally vigorous, was starved by insufficient food derived from the new crown, and became diminutive and shrunken (see Synophty).

Fig. 22.—Adhesion of the branches of two elms. 'Gard. Chron.,' 1849, p. 421.

The explanation of the fact that the stumps of felled fir trees occasionally continue to grow, and to deposit fresh zones of wood over the stump, depends on similar facts. In Abies pectinata, says Goeppert,[57] the roots of different individuals frequently unite; hence if one be cut down, its stump may continue to live, being supplied with nourishment from the adjacent trees to which it is adherent by means of its roots.

Fig. 23.—Adhesion of two roots of carrot. 'Gard. Chron.,' 1851, p. 67.

A not uncommon malformation in mushrooms arises from the confluence of their stalks (fig. 24), and when the union takes place by means of the pilei, it sometimes happens, during growth, that the one fungus is detached from its attachment to the ground, and is borne up with the other, sometimes, even, being found in an inverted position on the top of its fellow.[58]

The garden operations of budding, grafting and inarching have already been alluded to as furnishing illustrations of adhesion, but it may be well to refer briefly to certain other interesting examples of adhesion induced artificially; thus, the employment of the root as a stock, "root-grafting," is now largely practised with some plants, as affording a quicker means of propagation than by cuttings; and a still more curious illustration may be cited in the fact that it has also been found possible to graft a scion on the leaf in the orange.[59]

Fig. 24.—Section through two adherent mushrooms, the upper one inverted.

Mr. Darwin, in his work on the 'Variation of Animals and Plants,' vol. i, p. 395, alludes to the two following remarkable cases of fusion:—"The author of 'Des Jacinthes' (Amsterdam, 1768, p. 124) says that bulbs of blue and red hyacinths may be cut in two, and that they will grow together, and throw up a united stem (and this Mr. Darwin has himself seen), with flowers of the two colours on the opposite sides. But the remarkable point is, that flowers are sometimes produced with the two colours blended together." In the second case related by Mr. Trail, about sixty blue and white potatoes were cut in halves through the eyes or buds, and the halves were then joined, the other buds being destroyed. Union took place, and some of the united tubers produced white, others blue, while some produced tubers partly white and partly blue.

Adhesion of the axes of plants belonging to different species is a more singular occurrence than the former, and is of some interest as connected with the operation of grafting. As a general rule horticulturists are of opinion, and their opinion is borne out by facts, that the operation of grafting, to be successful, must be practised on plants of close botanical affinity. On the other hand, it is equally true that some plants very closely allied cannot be propagated in this manner. Contact between the younger growing tissues is essential to successful grafting as practised by the gardener, and is probably quite as necessary in those cases where the process takes place naturally. Although there is little doubt but that some of the recorded instances of natural or artificial grafting of plants of distant botanical affinities are untrustworthy, yet the instances of adhesion between widely different plants are too numerous and too well attested to allow of doubt. Moreover, when parasitical plants are considered, such as the Orobanches, the Cuscutas, and specially the mistleto (Viscum), which may be found growing on plants of very varied botanical relationship, the occurrence of occasional adhesion between plants of distant affinity is not so much to be wondered at. Union between the haulms of wheat and rye, and other grasses, has been recorded[60]. Moquin-Tandon[61] relates a case wherein, by accident, a branch of a species of Sophora passed through the fork, made by two diverging branches of an elder (Sambucus), growing in the Jardin des Plantes of Toulouse. The branch of the Sophora contracted a firm adhesion to the elder, and what is remarkable is that, although the latter has much softer wood than the former, yet the branch of the harder wooded tree was flattened, as if subjected to great pressure[62]. It is possible that some of the cases similar to those spoken of by Columella, Virgil[63], and other classical writers, may have originated in the accidental admission of seeds into the crevices of trees; in time the seeds grew, and as they did so, the young plants contracted an adhesion to the supporting tree. Some of the instances recorded by classical writers may be attributed to intentional or accidental fallacy, as in the so-called "greffe des charlatans" of more modern days.

Adhesion of the roots of different species has been effected artificially, as between the carrot and the beet root, while Dr. Maclean succeeded in engrafting, on a red beet, a scion of the white Silesian variety of the same species. In all these cases, even in the most successful grafts, the amount of adhesion is very slight; the union in no degree warrants the term fusion, it is little but simple contact of similar tissues, while new growing matter is formed all round the cut surfaces, so that the latter become gradually imbedded in the newly formed matter.

Synophty or adhesion of the embryo.—This often occurs partially in the embryo plants of the common mistleto (Viscum), but is not of common occurrence in other plants, even in such cases as the orange (Citrus), the CycadeÆ, ConiferÆ, &c., where there is frequently more than one embryo in the seed. Alphonse De Candolle has described and figured an instance of the kind in Euphorbia helioscopia, wherein two embryo plants were completely grafted together throughout the whole length of their axes, leaving merely the four cotyledons separate. A similar adnation has been observed by the same botanist in Lepidium sativum and Sinapis ramosa, as well as in other plants.[64] I have met with corresponding instances in Antirrhinum majus and in CratÆgus oxyacantha, in the latter case complicated with the partial atrophy of one of the four cotyledons. It is necessary to distinguish between such cases and the fallacious appearances arising from a division of the cotyledons. M. Morren has figured and described the union of two roots of carrot (Daucus), which were also spirally twisted. He attributes this union to the blending of two radicles, and applies the term "rhizocollesy" to this union of the roots.[65] Mr. Thwaites cites a case wherein two embryos were contained in one seed in a Fuchsia, and had become adherent. What is still more remarkable, the two embryos were different, a circumstance attributable to their hybrid origin, the seed containing them being the result of the fertilisation of Fuchsia coccinea (quere F. magellanica?) by the pollen of F. fulgens.

FOOTNOTES:

[30] Wydler, 'Flora,' 1852, p. 737, tab. ix.

[31] 'El. Ter. Veg.,' p. 254.

[32] 'Bull. Soc. Bot. Fr.,' 1857, p. 451.

[33] 'Bull. Acad. Belg.,' vol. xix, part ii, p. 335.

[34] 'Bull. Soc. Bot. Fr.,' 1860, p. 25.

[35] 'Bull. Soc. Bot. Fr.,' 1861, p. 147.

[36] 'Bull. Acad. Belg.,' vol. xviii, part ii, p. 498.

[37] See also Prillieux, 'Bull. Soc. Bot. Fr.,' 1861, p. 195.

[38] 'MÉm. Acad. Toulouse,' 5th Series, vol. iii.

[39] LinnÆa, vol. ii. p. 607.

[40] 'Journal Roy. Hort. Soc.,' new ser., vol. i. 1866, p. 200.

[41] 'Bull. Soc. Bot. Fr.,' 1861, p. 159.

[42] Ibid., 1859, p. 467.

[43] 'Flora,' 1858, p. 65, tab. ii.

[44] C. Morren. 'Bull. Acad. Belg.,' vol. xv (Fuchsia, p. 89); vol. xviii, p. 591. (Lobelia, p. 142); vol. xix, p. 352; vol. xx, p. 4.

[45] 'Bull. Soc. Bot. Fr.,' vol. vii, p. 625.

[46] Cramer, 'Bildungsabweichungen,' p. 56, tab. vii, fig. 10, figures a case wherein the two central flowers of the capitulum of Centaurea Jacea were united together.

[47] 'Bull. Bot.' tab. iii, figs. 4–6.

[48] 'MÉm. greffe Ann. Science Nat.,' ser. i, t. xxiv, p. 334.

[49] "Mespilus portentosa." Poit. et Turp., 'Pomol. Franc.,' liv, xxxi, p. 202, pl. 202.

[50] Duchesne, 'Hist. Nat. Frais.,' p. 79.

[51] De Cand., 'Phys. VÉgÉt.,' tom. ii, p. 781.

[52] Sched. de monstr. plant. 'Act. Helv.,' tab. i, fig. 8.

[53] 'MÉm. greffe,' loc. cit., tab. xxiv, p. 334.

[54] 'Bull. Soc. Bot. Franc.,' 8, pp. 73 and 351, tab. ii; and RÖse. 'Bot. Zeit.,' x, p. 410.

[55] NymphÆa lutea, Æsculus Hippocastanum, &c. See Moquin, 'El. Ter. Veg.,' p. 277.

[56] C. Martins, 'Promenade Botanique,' p. 8.

[57] 'Ann. Sc. Nat.,' t. xix, 1843, p. 141, tab. iv.

[58] 'Ann. Nat. Hist.,' ser. 2, vol. ix, tab. xvi. 'Phytologist,' 1857. p. 352, &c.

[59] Quoted from the 'Revue Hortic.' in 'Gard. Chron.,' 1866, p. 386.

[60] Senebier, 'Phys VÉgÉt.,' t. iv, p. 426. The same author also cites Romer as having found two plants of Ranunculus, from the stem of which emerged a daisy. As it is not an uncommon practice to stick a daisy on a buttercup, it is to be hoped no hoax was played off on M. Romer.

[61] 'El. Ter. Veg.,' p. 289.

[62] An instance of this kind is cited in Dr. Robson's memoir of the late Charles Waterton, from which it appears that two trees, a spruce fir and an elm, were originally planted side by side, and had been annually twisted round each other, so that they had in places grown one into the other, with the result of stunting the growth of both trees, thus illustrating, according to the opinion of the eccentric naturalist above cited, the incongruous union of Church and State!

[63] See Daubeny, 'Lectures on Roman Husbandry,' p. 156.

[64] A. P. De Candolle, 'Organ VÉgÉt.,' t. ii, p. 72, tab. liv, fig. 1.

[65] 'Bull. Acad. Belg.,' t. xx, part i, 1852, p. 43.

PART II.
INDEPENDENCE OR SEPARATION OF ORGANS.

Under this head are included all those instances wherein organs usually entire, or more or less united, are, or appear to be, split or disunited. It thus includes such cases as the division of an ordinarily entire leaf into a lobed or partite one, as well as those characterised by the separation of organs usually joined together. Union, as has been stated in a previous chapter, is the result either of persistent integrity or of a junction of originally separate organs, after their formation; so in like manner, the separation or disjunction of parts may arise from the absence of that process of union which is habitual in some cases, or from an actual bon fide separation of parts originally united together. In the former case, the isolation of parts arises from arrest of development, while in the latter it is due rather to luxuriant growth. A knowledge, as well of the ordinary as of the unusual course, of development in any particular flower is thus required in order to ascertain with accuracy the true nature of the separation of parts. The late Professor Morren[66] proposed the general term Monosy (???s??) for all these cases of abnormal isolation, subdividing the group into two, as follows—1, Adesmy (a-des??), including those cases where the separation is congenital; and 2, Dialysis (d?a???), comprising those instances where the isolation is truly a result of the separation of parts previously joined together. Adesmy, moreover, was by the Belgian savant said to be homologous when it occurred between members of the same whorl, e.g. between the sepals of an ordinary monosepalous calyx, or heterologous when the separation took place between members of different whorls, as when the calyx is detached from the ovary, &c. The former case would thus be the converse of cohesion, the latter of adhesion.

To the adoption of these words there is this great objection, that we can but rarely, in the present state of our knowledge, tell in which group any particular illustration should be placed.

The terms adopted in the present work are, for the most part, not necessarily intended to convey any idea as to the organogenetic history of the parts affected. Where a single organ, that is usually entire, becomes divided the term Fission is used; in cases where parts of the same whorl become isolated, the word Dialysis is employed, and in the same sense in which it is generally used by descriptive botanists, and where the various whorls become detached one from the other, the occurrence is distinguished by the application of the term Solution.

[66] 'Bull. Acad. Belg.,' t. xix, part iii, 1852, p. 315.

CHAPTER I.
FISSION.

When an organ becomes divided it receives at the hands of descriptive botanists the appellations cleft, partite, or sect, according to the depth of the division; hence in considering the teratological instances of this nature, the term fission has suggested itself as an appropriate one to be applied to the subdivision of an habitually entire or undivided organ. It thus corresponds pretty nearly in its application with the term Chorisis or "dÉdoublement," or with the "disjonctions qui divisent les organes" of Moquin-Tandon.[67] It is usually, but not always, a concomitant with hypertrophy, and dependent on luxuriance of growth.

It must be understood therefore that the term, as generally applied, does not so much indicate the cleavage of a persistent organ, as it does the formation and development of two or more growing points instead of one, whence results a branching or forking (di-tri-chotomy) of the affected organ. In some instances it seems rather to be due to the relative deficiency of cellular, as contrasted with fibro-vascular tissue.

Fission of axile organs.—This condition is scarcely to be distinguished from multiplication of the axile organs (which see). A little attention, however, will generally show whether the unusual number of branches is a consequence of the development of a large number of distinct shoots, as happens, for instance, when a tree is pollarded, or of a division of one. M. Fournier[68] gives as an illustration the case of a specimen of Ruscus aculeatus in which there occurred a division of the foliaceous branches into two segments, reaching as far as the insertion of the flower, but no further. He also mentions lateral cleavage effected by a notching of the margin, the notch being anterior to the flowers and always directed towards their insertion. In the allied genus DanaË, Webb, 'Phyt. Canar.,' p. 320, describes the fascicles of flowers as in "crenulis brevibus ad marginem ramulorum dispositis." Sometimes, on the other hand, DanaË has a fascicle of flowers inserted on the middle of the upper surface, as in Ruscus. Wigand mentions an instance in Digitalis lutea, where the upper part of the stem was divided into six or seven racemes; possibly this was a case of fasciation, but such a division of the inflorescence is by no means uncommon in the spicate species of Veronica. I have also seen it in Plantago lanceolata, Reseda luteola, Campanula medium, Epacris impressa, and a bifurcation of the axis of the spikelet within the outer glumes in Lolium perenne[69] and Anthoxanthum odoratum. In the Kew Museum is preserved a cone of Abies excelsa,[70] dividing into two divisions, each bearing bracts and scales. A similar thing frequently occurs in the male catkins of Cedrus Libani (fig. 25).

Fission of foliar organs.—Many leaves exhibit constantly the process of fission, such as the Salisburia adiantifolia, and which is due perhaps as much to the absence or relatively small proportion of cellular as compared with vascular tissue, as to absolute fission. In the same way we have laciniated leaves of the Persian lilac, Syringa persica, and Moquin mentions instances in a species of Mercurialis in which the leaves were deeply slashed. In Chenopodium Quinoa the leaves were so numerous and the clefts so deep, that the species was hardly recognisable, while on a branch of Rhus Cotinus observed by De Candolle the lobes were so narrow and so fine as to give the plant the aspect of an Umbellifer. Wigand ('Flora,' 1856, p. 706) speaks of the leaves of Dipsacus fullonum with bi-partite leaves; Moquin mentions the occurrence of a leaf of an oleander bi-lobed at the summit, so as to give the appearance of a fusion of two leaves. Steinheil has recorded an instance in Scabiosa atropurpurea in which one of the stem leaves presented the following peculiarities. It was simple below, but divided above into two equal lobes, provided each with a median nerve.[71] Steinheil has also recorded a Cerastium in which one of the leaves was provided with two midribs; above this leaf was a group of ternate leaves. I have seen similar instances in the common Elm, Ulmus campestris, and also in the common nettle, Urtica dioica, the leaves of which latter thus resembled those of Urtica biloba, which are habitually bilobed at the summit. M. Clos[72] mentions an instance where the terminal leaf and first bract of Orchis sambucina were divided into two segments. The same author also mentions the leaves of Anemiopsis californica, which were divided in their upper halves each into two lobes—also leaves of a lentil springing from a fasciated stem and completely divided into two segments, but with only a single bud in the axil. The axillary branches in like manner showed traces of cleavage. Fig. 26 represents a case of this kind in Lamium album, conjoined with suppression of the flowers on one side of the stem. I have also in my herbarium a leaf of Arum maculatum, with a stalk single at the base, but dividing into two separate stalks, each bearing a hastate lamina, the form of which is so perfect that were it not from the venation of the sheath it would be considered that there was here a union of two leaves rather than a bifurcation of one. A garden Pelargonium presented the same appearance.

Fern fronds are particularly liable to this kind of subdivision, and they exhibit it in almost every degree, from a simple bifurcation of the frond to the formation of large tufts of small lobes all formed on the same plan by the repeated forking of the pinnules. These may be considered as cases of hypertrophy.

Moquin-Tandon, at a meeting of the Botanical Society of France (April 3rd, 1858) exhibited a leaf of Cerasus Lauro-Cerasus divided in such a manner as to resemble a leaf of Citrus or of Phyllarthron. In this case, therefore, the disunion must have taken place laterally, and not from apex towards base, as is most common. The leaves of the common horse-radish, Cochlearia Armoracia, are very subject to this pinnated subdivision of the margin, and numerous other illustrations might be given.

A. Braun describes a singular case in a leaf of Irina glabra wherein the blade of the leaf on one side was deeply and irregularly laciniated, the other side remaining entire. (Verhandl., d. 35, Naturforscherversammlung, tab. 3.) Laciniate varieties of plants are of frequent occurrence in gardens where they are often cultivated for their beauty or singularity; thus, there are laciniated alders, fern-leaved beeches and limes, oak-leaved laburnums, &c. A list of several of these is subjoined. A similar fission takes place constantly in the cotyledons of some plants, sometimes, as in ConiferÆ, to such an extent as to give an appearance as if there were several cotyledons.[73]

It is not always easy to recognise, at a first glance, whether the division be the result of disunion or of an incomplete union of two leaves, but we may be guided by the number of leaves in the cycle or the whorl. The number is complete in cases of partial disjunction, while in cases of fusion it is incomplete. Again, in instances of disjunction, there is only one point of origin, but, when two leaves are grafted together, two such points may generally be detected at the base of the leaf, or a transverse section of the leaf-stalk will show indications of fusion. The number and position of the midribs will also serve as a guide, as in cases of fusion there are generally two or more midribs, according to the number of fused leaves; but as Moquin well remarks, this latter character cannot be always depended upon, for the median nerve may divide without any corresponding separation of the cellular portions of the leaf. The author just quoted cites examples of this kind in Cardamine pratensis, Hedera Helix, Plantago major, Geranium nodosum.

The following list of plants commonly producing leaves that are cleft or divided, to a greater extent than is usual in the species, is mainly taken from one given by Schlechtendal, 'Bot. Zeit.,' 1844, p. 441, with additions from other sources. The ! indicates that the author has himself met with the deviation in question. Many are cultivated as garden varieties under the names here given.

Fission of the petals, &c.—The floral leaves are subject to a similar process of cleavage to that which has just been mentioned as taking place in the leaves. This, indeed, occurs very often as a normal occurrence as in the petals of mignonette (Reseda), or those of Alsine media and many other plants. Here, however, we have only to allude to those instances in which the cleavage occurs in flowers whose sepals or petals are usually entire. Under this category Moquin mentions a petal of Brassica oleracea completely split into two. LinnÉ in his 'Flora Lapponica' (pp. 145 and 164) mentions quadrifid petals of Lychnis dioica, and much divided petals of Rubus arcticus. Among other plants subject to this division of sepals or petals may be mentioned as having come within the writer's personal observation, Ranunculus Lingua, R. acris, Papaver somniferum, and others of this genus, Saponaria sp., Dianthus, Narcissus, &c.

In some of the garden varieties of Cyclamen the corolla looks at first sight as if double, and the plan of the flower is oblong or elliptical, instead of circular. In these flowers each lobe of the corolla is divided almost to the base into two lobes, so that there appear to be ten lobes to the corolla instead of five, as usual. The stamens are normal in form and number in these flowers.

In the paroquet tulips of gardeners the segments of the perianth are deeply and irregularly gashed, the segments occasionally becoming rolled up and their margins coherent so as to form little tubular spurs. I have also noticed the segments of the perianth in Crocus and Colchicum deeply cleft, so much so sometimes, as to equal in this particular the stigmas. In the flowers of a species of Oncidium, communicated to me by Mr. Currey, the lip was divided into three segments perfectly distinct one from the other, but confluent with the column; the two side pieces had callosities at the upper edge close to the base, the central piece had a similar wartlike process in its centre. In these flowers the ovary, the stigma, and the anther were all in a rudimentary condition. Some verbenas raised by Mr. Wills offer a curious illustration of this condition. It will be remembered that some of the lobes or petals of a verbena are normally divided at the base to a slight degree, but in the flowers in question this is carried to such an extent that the enlarged lobes are pushed into the centre of the flower and simulate, at a first glance, a distinct and separate organ, though in reality it is but an enlargement of what occurs normally.[74]

The instances given in this chapter have all been cases wherein the division or the accessory growth has taken place in one plane only and that plane the same as that of the affected organ, but there are other examples, probably equally due to fissiparous division, where the new growth is either parallel to, or even at angle with the primary organ. Of such nature are some of those instances wherein two leaves appear to be placed back to back. These partake of the nature of excrescences or of exaggerated developments, and hence will be more fully treated of under the head of hypertrophy. It must be remembered that in some of these cases the fission may be a resumption of characters proper to the species under natural conditions, but lost by cultivation or otherwise. Thus, Mr. Buckman accounts for "finger-and-toe" in root-crops on the principle of reversion to the wild form.

CHAPTER II.
DIALYSIS.

This term is here made use of in the same sense as in descriptive botany, to indicate the isolation of parts of the same whorl; it is thus the opposite of cohesion. Morren, as has been previously stated, employed the word in a different sense, while Moquin-Tandon[75] included cases of this description under the category of "Disjonctions qui isolent les organes."

Dialysis, as here understood, may be the result of an arrest of development, in consequence of which parts that under ordinary circumstances would become fused, do not do so; or, on the other hand, it may be the result of an actual separation between parts primitively undivided. As it is not possible in every case to distinguish between the effects of these two diverse causes, no attempt is here made to do so.

Dialysis of the margins of individual foliar organs.—In cases where the leaf or leaf-like organ is ordinarily tubular or horn-like in form, owing to the cohesion of its edges, it may happen either from lack of union or from actual separation of the previously united edges, that the tubular shape is replaced by the ordinary flattened expansion. Thus, in Eranthis hyemalis, wherein the petals (nectaries) are tubular and the sepals flat, I have met with numerous instances of transition from the one form to the other, as shown in fig. 9, p. 24.

It is, however, in the carpels that this separation occurs most frequently. When these organs appear under the guise of leaves, as they often do, their margins are disunited, so that the carpel becomes flat or open. This happens in the strawberry (Fragaria), the columbine (Aquilegia), in Trifolium repens, Ranunculus Ficaria, &c.[76]

Dialysis of the parts of the same whorl:—calyx.—The separation of an ordinarily coherent series into its constituent parts is necessarily of more common occurrence than the foregoing. As here understood, it is the precise converse of cohesion, and it may be represented diagrammatically by a dotted line above the letters denoting the sepals, petals, &c. When this change happens in the calyx we have the gamosepalous condition replaced by the polysepalous one, as thus represented:

as in a calyx of five coherent sepals.

Detachment of this kind occurs not unfrequently, as in Primula vulgaris, Trifolium repens, &c. In RosaceÆ and PomaceÆ this separation of the calyx is of the more moment, as it has reference to the structure of the inferior ovary, as will be more fully mentioned hereafter. Here, however, a case recorded by M. J. E. Planchon may be alluded to[77] wherein a quince fruit (Cydonia) was surmounted by five leaves, the surface of the pome being marked by as many prominences, which apparently corresponded to the five stalks of the calycine leaves. In this specimen, then, the inferior position of the ovary appeared to be not so much due to an expansion of the fruit stalk, as to the fusion of the hypertrophied stalks of the sepals. Some of the malformations among Cucurbits point to a similar structure. It is probable that in many of these cases the so-called inferior ovary is partly axial partly foliar, i.e., sepaline, and partly carpellary in its nature.

Dialysis of the sepals in calyces that are usually gamosepalous has been most frequently observed in RosaceÆ, PomaceÆ, UmbelliferÆ, less commonly in LeguminosÆ, also in the following genera:—Primula, Symphytum, Gentiana, Campanula, &c.

Dialysis of the corolla is likewise of frequent occurrence, either partially or to such an extent as to render the corolla truly polypetalous. Among LabiatÆ the upper lip of the corolla may be often met with partially cleft, as it is constantly in Phlomis biloba, or more markedly among the LobeliaceÆ.

In the CompositÆ, a similar separation of the petals is not infrequent, thus showing frequent transitional stages between the labiatifloral and tubulifloral divisions respectively. The ligulate corollas also may often be found in Chrysanthemums, Dahlias, &c., more or less deeply divided into their component parts.

A more complete separation occurs not unfrequently in Campanula, Rhododendron, Phlox, &c. Figs. 30 and 31 illustrate dialysis of the corolla; the first in Correa, the second in Campanula.

The following list contains the names of the genera in which this separation of the petals of an ordinarily gamopetalous flower takes place most frequently.

This list does not include those very numerous cases in which this change is associated with more or less complete frondescence or leafy condition of the petals.

Dialysis of the stamens.—A similar isolation of the stamens occurs occasionally; for instance, when Mallows (MalvaceÆ) become double, one of the first stages of the process is often the disjunction of the stamens, and a similar dissociation occurs in LeguminosÆ and CompositÆ, as in Tragopogon, as related by Kirschleger, in HypochÆris by Wigand, and in Coreopsis by Schlechtendal.

Dialysis of the carpels.—In the case of the carpels this disunion is more frequent than in the stamens. M. Seringe[78] figures carpels of Diplotaxis tenuifolia more or less completely separated one from the other; indeed, this separation is very common amongst CruciferÆ and UmbelliferÆ.

Generally speaking, the disunion is complicated with frondescence—but not always so. I have, in my herbarium, specimens of Convallaria majalis, Commelyna sp., and of Lilium auratum, in all of which the three carpels are completely disjoined, and present three styles, three stigmas, &c., without any other change. Engelmann[79] speaks of three classes of this malformation. 1st, that in which the carpels separate one from the other without opening, as in the lily just alluded to; 2nd, that in which the ovary remains closed, but loses its internal partitions, as in a case mentioned by Moquin in Stachys sylvatica, in which, owing to imperfect disjunction, the two bi-lobed carpels were changed into a nearly one-celled capsule;[80] and 3rd, those cases in which the carpels are open and foliaceous.

Disjunction is more frequent in dry fruits than in fleshy ones. In the latter instance it happens at an early stage of existence, and the pericarp becomes more or less leafy, losing its faculty of becoming fleshy, as in Prunus Cerasus and Amygdalus persica; nevertheless, fleshy fruits sometimes become disunited. I have seen a case similar to that mentioned by M. Alphonse de Candolle in Solanum esculentum, in which the pericarp became ruptured, and the placentas protruded. A like occurrence has also been observed in a species of Melastoma.[81] This is analogous to what happens in Caulophyllum and Slateria. Disjunction of the carpels is not rare in oranges. Sometimes this takes place regularly, at other times irregularly; occasionally in such a manner as to give the appearance of a hand and fingers to the fruit. Of one of these, Ferrari,[82] in the curious volume below cited, speaks thus: "Arbor profusissima, quia dat utraque manu; imo quia vere manus dat in poma conversis; utque magis munifica sit poma ipsa convertit in manus."

M. Duchartre[83] mentions a semi-double flower of orange with eight to ten distinct carpels in a whorl, and occasionally several whorls one above another. De Candolle[84] considers the rind of the orange as a production from the receptacle, and this view is confirmed by the specimens of Duchartre, in which the carpels were quite naked or had a common envelope truncated, and open above to allow of the passage of the styles and stigmas.

It frequently happens in conjunction with this separation of the carpels one from the other, that a lack of union manifests itself between the margins of the individual carpels themselves. Very numerous cases of this kind have been recorded, and the double tulips of gardens may be referred to as showing this condition very frequently. In connection with this detachment of the carpels, a change in the mode of placentation is often to be observed, or two or more kinds may be seen in the same pistil, as in double-flowered saponarias, many Crucifers, &c., as alluded to under the head of displacements of the placenta.

CHAPTER III.
SOLUTION.

The isolation or separation of different whorls that are ordinarily adherent together is by no means of rare occurrence. Were it not that the isolation is often congenital, the word detachment would be an expressive one to apply to these cases, but as the change in question occurs quite as often from a want of union, an arrest or stasis of development, as from a bon fide separation, the word solution seems to be, on the whole, the best. It corresponds in application to the word liber (calyx liber, &c.), in general use by descriptive botanists. As here employed, the term nearly corresponds with the "adesmie hetÉrologue" of Morren. Moquin Tandon does not make any special subdivision for the class of cases here grouped together, but places them all under "Disjonctions qui isolent les organes." It seems, however, desirable to have a separate word to express the converse condition of adhesion, and for this purpose the term solution, as above stated, is here employed. Diagrammatically, the condition may be expressed by placing a dotted line at the side of the letters thus:

would indicate the disjunction of the sepals from the carpels (c), in contradistinction to adhesion, which may be represented by the unbroken line thus:

Solution of the calyx from the ovary.—Of all the instances of adhesion which take place under ordinary circumstances, that between the calyx and the ovary is perhaps the most common. The calyx adhÆrens or superus is a structural characteristic to which all botanists attach considerable importance; so that when exceptional cases occur in which the calyx becomes detached from the ovary, becomes, that is, inferus or liber, a proportionate degree of interest attaches to the irregularity. It is not within the scope of the present work to inquire whether this detachment be real or merely apparent, arising from a want of union between parts ordinarily united together. This point must be left to the organogenists to decide in each particular case. So also the question as to what share, if any, the expanded and dilated flower-stalk may take in what are usually called inferior ovaries, can be here only incidentally touched upon.

Among RosaceÆ, the change in question is very common, especially in conjunction with an elongation of the axis of the flower (apostasis) and with prolification, though it is by no means always co-existent with these malformations. When this alteration in the apparent relative position of calyx and carpels occurs in roses (Rosa) the appearances are generally such as to indicate that the "hip" of the rose is a dilatation of the peduncle, continuous above with the coherent bases of the sepals; this inference seems also to be borne out by what happens in the PomaceÆ. In some cases in this sub-order, the calyx becomes detached from the carpels, so that the latter organs become more or less "superior," and distinct one from the other. This happens constantly in the double-flowered thorn, CratÆgus Oxyacantha, in some blossoms of which the hollowed end of the peduncle still invests the base of the carpels, leaving the upper portions detached. In apples flowers are occasionally met with of greater size than usual and on longer stalks, so that the whole looks more like a rose than an apple blossom. In these cases it will usually be found that the calyx consists of distinct sepals, without a trace of the ordinary swelling beneath the flower. The petals are often more numerous than usual; the stamens variously changed, and the carpels sometimes absent; at other times, as in the instance figured in the adjacent woodcuts, figs. 36, 37, consisting of separate, superior ovaries, sometimes destitute of ovules, or, at other times, having two of these bodies.[85]

This condition accords precisely with the account of the development of the flowers in PomaceÆ as given by Payer, Caspary, and others, so that the flowers above described would owe their deficiency of the swollen receptacle to an arrest of development. M. Germain de Saint Pierre, among other malformations of the rose, presented to the Botanical Society of France in 1854[86] two specimens which are of special interest as relating to this contested point. In the one, the swollen portion beneath the flower was surmounted by five perfect leaves, as, indeed, is not infrequent in such malformations; here, then, the calyx could have had little or no share in the production of the swelling in question. In the other, the swollen portion was actually above the insertion of the sepals here represented by five perfect leaves.

On the other hand, M. Planchon's specimen of the Quince before alluded to, not to mention other instances, tends to show that the bases of the sepals do sometimes enter into the composition of the pome. And, indeed, in many of these cases it would be impossible to say where the axial or receptacular portion ended, and the foliar portion began. As both from normal organogeny as well as from unusual conformation contradictory inferences may be drawn, it would obviously be unsafe to attempt the explanation of the so-called calyx-tube in general from any particular instances; so far as RosaceÆ are concerned, there is so much variation in the relative position of calyx and carpels under ordinary circumstances, that it is no matter for surprise that similar diversities should exist in teratological cases. A similar remark will apply to SaxifragaceÆ, CucurbitaceÆ, MyrtaceÆ, BruniaceÆ, RubiaceÆ, and other families of like conformation.

In UmbelliferÆ, a detachment of the calyx from the ovaries frequently occurs, sometimes without any other change; at other times attended by more serious alterations. So far as can be judged from exceptional occurrences of this kind, it would appear that in this order the axis or flower-stalk does not, in any material degree, enter into the composition of the fruit.

In the Rubiaceous genus Bikkhia, as mentioned by Duchartre, the ovary is completely inferior, but when the fruit arrives at maturity four small leaves are detached from its surface which had previously adhered to it, and which it seems reasonable to consider as the sepals.

In CampanulaceÆ a similar separation of calyx from the ovary may be occasionally met with. On the other hand, the occasional formation of a leaf on the inferior ovary of those plants would indicate the axial nature of the fruit. In CampanumÆa and Cyclodon the calyx is inferior, while the corolla is superior. In the last-named genus this peculiarity "is carried to the highest degree, the sepals being, in C. parviflorum, placed on the peduncle of the flower far removed from the base of the corolla and ovary, whilst in C. truncatum and in CampanumÆa they adhere to the base of the tube of the corolla."[87] In this order, then, as in SaxifragaceÆ, BruniaceÆ, &c., no hasty conclusion should be drawn as to the nature of the fruit. In Brunia microphylla the ovary is superior, enclosed within but not adnate to the cup-like calyx, to which latter, however, the petals and stamens are attached.

In OnagraceÆ (Jussieua), as also in CactaceÆ (Opuntia), buds have been observed on the surface and edges of the inferior ovary. Indeed, in the former genus, they have been produced artificially, but as buds may be formed on foliar as well as on axial organs, the fact cannot be made great use of in support either of the foliar or axial nature of the inferior ovary. In Epilobium, I have met with four perfect leaves at the summit of the ovary, in the place usually occupied by the sepals. This would also favour the notion that the axis entered into the constitution of the fruit in this genus.

Mr. B. Clarke, in his 'New Arrangement of Phanerogamous Plants,' p. 4, cites a case wherein the perianth was completely detached from the surface of the ovary in Cannabis sativa.

It must be borne in mind that some of the recorded instances of change in the relative position of the calyx and pistil ought more properly to be referred to a substitution of carpels for stamens, as in Begonia, Fuchsia, &c. Among CucurbitaceÆ, examples have been recorded, both of the detachment of the calyx from the ovary,[88] and of the partial conversion of some of the anthers of the male flower to carpels.

The very singular mode of germination of Sechium edule in which the fruit, instead of rotting, becomes thickened into a kind of rhizome or tuber, is a fact that should not be overlooked in investigating the true nature of the fruit in this order.

The following are the genera in which the change has been most frequently observed:

Solution of the stamens from the petals.—A separation of the stamens from the petals in flowers, wherein those organs are usually adherent one to the other does not often occur unattended by other changes. It has been observed in CobÆa scandens (Turpin), in Antirrhinum majus, and in many double flowers.

Partial detachment of the stamens from the styles occurs frequently in semi-double flowers of Orchis.[89]

PART III.
ALTERATIONS OF POSITION.

Necessarily connected with changes in the arrangement of organs are similar alterations in their position; so closely, indeed, that but for convenience sake, it would be unnecessary to treat them separately. There are, however, some anomalous developments affecting the relative position of organs that could hardly be treated of under any of the preceding paragraphs. There are, also, certain rare instances where an organ is not so much displaced as misplaced; that is to say, it is developed on or from a portion of the plant, which under usual circumstances does not produce such an organ. In the former instance, the altered position is due to or coexistent with other changes, but in the latter case the new growth may spring from organs otherwise in nowise different from ordinary. The word Displacement is here used to signify the unusual position of an organ; while Heterotaxy may serve to include those cases where a new growth makes its appearance in an unwonted situation, as, for instance, a leaf-bud on a root, &c. Prolification is also included under this heading, the unusual position of the buds in these cases being of graver import than the mere increase in number. Alterations in the position of the sexual organs are spoken of under the head of Heterogamy.

CHAPTER I.
DISPLACEMENT.

Real or apparent displacement of organs from their usual position is an almost necessary consequence of, or is, at least, coexistent with a large number of teratological phenomena. It is obvious that abnormal unions or disunions, suppressions, hypertrophies, &c., are very liable to bring about or to be accompanied with changes in the position, either of the parts directly affected or of adjoining organs.

In this place, then, it is merely necessary to allude to some of the more important displacements, and to refer for further details to the sections relating to those irregularities of growth on which the displacement depends.

Displacement of bulbs.—I owe to the kindness of Mr. James Salter a tulip bulb which had been dug up after flowering, and from the base of which were suspended several small bulbs; and I have since seen another specimen showing the same unusual arrangement. The explanation of these formations seems to be that they correspond to the bulbils ordinarily found in the axils of the scales of the parent organ, and which, in some way or another, have been displaced and thrust into the ground. Professor de Vriese figures something of the same kind in Ixia carminosa.[90]

Of somewhat different nature to those above described was an anomaly described by M. Gay at a meeting of the Botanical Society of France, April 8th, 1859. The plant affected was Leucoium Æstivum, and the changes observed were apparently attributable to a simple separation of two leaves that are usually contiguous. "Suppose," says M. Gay in describing this malformation, "the first leaf of the terminal bud separated by a long internode from the other leaves, which remain closely packed; and further, suppose an evident thickening of the upper portion of the lengthened internode, and there will be not only a single bulb, bearing with the leaves of the present year all the remnants of the leaves of the two preceding years, but two bulbs placed one above another, on the same axis, separated by the length of the internode."

Displacements affecting the inflorescence.—These are, for the most part, dependent on hypertrophy, elongation, atrophy, spiral torsion, &c., but there are a few instances of a different nature, which may here be alluded to as not being coincident with any of the phenomena just mentioned. Sometimes these deviations from the ordinary position have the more interest as affecting characters used to distinguish genera; thus one of the distinctions between rye-grass (Lolium) and wheat (Triticum) resides in the relative position of the spikelets and the main stem; in Triticum the spikelets are placed with their backs against the rachis, in Lolium with one edge against it; but in a specimen of rye-grass that has come under my own observation, the arrangement was that of Triticum.

M. Kirschleger relates having found a specimen of Leucanthemum pratense, in which the ligulate female flowers were growing singly in the axils of the upper leaves of the stem.[91] The ordinary capitulum would here seem to have been replaced by a spike or a raceme. A less degree of this change wherein a few flowers may be found, as it were, detached from the ordinary capitulum may often be observed in CompositÆ, DipsacaceÆ, &c. I have also met with specimens of Lamium album in which some of the fascicles or clusters of flowers in place of being placed at the same level on opposite sides of the stem were placed alternately one above another.

Caspary[92] mentions a flower of Aldrovanda vesiculosa, which was elevated on a stalk that was adherent to the stem for a certain distance, and then separated from it. This flower, with the leaf to which it was axillary, evidently belonged to the whorl beneath, where there was a corresponding deficiency. Another flower of the same plant bore on its pedicel a small leaf, which was doubtless the bract raised above its ordinary position.

M. Fournier mentions an instance in Pelargonium grandiflorum, where, owing to the lengthening of the axis, the pedicels, instead of being umbellate, had become racemose; and I owe to the kindness of Dr. Sankey a somewhat similar specimen, but in a less perfect condition. Here there was but a single flower, and that rudimentary, placed at the extremity of the axis. There were several bracts beneath this flower disposed spirally in the 1/3 arrangement, all being empty, excepting the terminal one. In like manner, a head of flowers becomes sometimes converted into an umbel.

Displacement of leaves.—A cohesion of parts will sometimes give rise to an apparent displacement, but the true nature of the malformation can, in general, be readily made out.

Steinheil[93] found a specimen of Salvia Verbenaca, the leaves of which presented very curious examples of displacement arising from cohesion. Two of these leaves placed at the base of a branch were completely fused in their lower thirds, and divided into two distinct lobes at the upper part; each of these lobes seemed to be as large as the limb of an ordinary leaf. Above these was another very broad one, apparently entire, but evidently produced by a complete cohesion of two. This completely fused leaf alternated in position with the imperfectly fused one below it; the alternation is explained by supposing that the opposite leaves of each pair were directed one towards the other, and became fused, and that thus resulted the displacement. The dislocation of the organs took place in one direction for one pair of leaves, and in another direction for the other pair, hence the alternation. Thus, leaves normally opposite and decussate may, by fusion, become alternate. A similar instance occurred to the writer in Lysimachia vulgaris, wherein the changes arising from fusion and suppression of parts, &c., were very considerable; as far as the leaves were concerned they presented the following arrangement in succession from below upwards:—first verticillate, then opposite, then spirally alternate, lastly opposite.[94] The term "diremption" has sometimes been applied to cases where leaves are thus apparently dragged out of position.In Tradescantia virginica I have met with opposite connate leaves; the altered position, however, being due to the union of two stems.

Twisting of the stem is a frequent cause of the displacement of leaves (see spiral torsion), as also hypertrophy, whether that excess of development take place laterally or lengthwise (see elongation). Atrophy or suppression will also frequently bring about an alteration in the position of leaves; sometimes in such a manner that the place of the suppressed organ is occupied by another one. One of the most curious instances of displacement of leaves arising from suppression is that mentioned by Morren,[95] where, in Gesnera Geroltiana, a large leaf apparently occupied the extremity of the axis, a position which, under ordinary circumstances, no leaf could assume. The explanation given by the Belgian professor is, that the axis in this case, instead of throwing off a pair of leaves, one on each side, had from some cause or another produced only one; this one not only being much larger than ordinary, but brightly coloured, thus assuming some of the characteristics as well as the position of the inflorescence.

Alterations in the usual arrangement of leaves, however, are not always dependent on or coexistent with other teratological changes, but may simply depend on a natural elongation of the internodes, or on fission or multiplication; for instance, in some conifers, such as the Larch, (Abies Larix) or Pinus pinea, there may be found at different stages in the growth of the branches leaves in crowded fascicles or tufts; while, when growth is more rapid, the leaves may be disposed in a spiral or alternate manner.

In the yew (Taxus) the leaves at the ends of the shoots not unfrequently lose their usual distichous arrangement and become arranged in a close spiral manner, the elongation of the shoot being arrested. This appears to be the result of the injury effected by some insect.

So, too, the alteration from verticillate to spiral, or vice versÂ, may take place without any other notable change.[96] This may frequently be seen in Rhododendrons.

Displacement of the parts of the flower.—This subject is partly touched on in the chapters on solution, adhesion, and in those on hypertrophy, elongation, prolification, &c., so that in this place it is only requisite to offer a few general remarks, and to refer to other sections for further details. Morren, in referring to displacement of the floral organs, mentions an instance in a Fuchsia, wherein the four petals in place of being alternate with the sepals were placed in front of them, owing to the adhesion that had taken place between the petals and the stamens. He speaks of this transposition as metaphery.[97] The same author also gives an account of the displacement of several of the organs of the flower in Cypripedium insigne, the displacement being consequent, apparently, on a spiral torsion proceeding from right to left, and involving the complete or partial suppression of several of the organs of the flower. The dislocation of organs in a spiral direction led Morren to apply the term "speiranthie" to similar deviations from the usual construction. Changes of this kind among OrchidaceÆ are by no means uncommon; the following may be cited by way of illustration. In a specimen of Oncidium cucullatum furnished me by Mr. Anderson, well known for his success as a cultivator of these plants, there was, associated with a cohesion of one sepal with another, and probably dependent on the same cause, a displacement of the sepals and petals—so that all were dragged out of place. This dislocation may be better appreciated by the accompanying formula than even by the woodcut. Let the usual arrangement be thus represented:

S standing for sepal, P for petal, L for lip, ST for stamen; then the dislocated form may be represented thus:

In a specimen of Cypripedium also furnished by Mr. Anderson the appearance was as represented in the accompanying figure and diagrams, figs. 44, 45. Referring to the plan of the natural arrangement at fig. 46, it will be seen that an explanation of the peculiar appearance of the flower may be arrived at by supposing a disunion and lateral displacement of the upper segment of the outer perianth together with the complete absence of the lower one. In the second or inner whorl of the perianth the lip is merely a little oblique on one side, but the lateral petals are distorted, displaced, and adherent one to the other and to the column, while the posterior shield-like rudimentary anther is completely wanting.

In a specimen of Lycaste Skinneri similar changes were observed, as shown in the plan, fig. 47. Here the posterior sepal was deficient, the two lateral ones were present, one of them with a long tubular spur, o o; of the two lateral petals, i i, one was twisted out of place, so as partially to occupy the place of the deficient sepal; the lip was represented by two three-lobed segments, l, one above and within the other. The column and ovary of this flower were in their normal condition.

Cohesion of two or more segments of the perianth is frequently associated with displacements of this nature: thus, in a flower of Dendrobium nobile, a diagram of which is given at fig. 48, the uppermost sepal was coherent with one of the lateral ones, and at the same time diminished in size, and, as it were, dragged out of position. All the other organs of the flower are also more or less displaced, forming a minor degree of the change already alluded to, and which Morren termed speiranthy. The changes will be better appreciated by comparing them with fig. 49, a diagram showing the natural arrangement of parts in this species.

Sometimes the displacement seems consequent on hypertrophy of one of the parts of the flower, the disproportionate size of one organ pushing the others out of place. This was the case in a violet, fig. 50, in which one of the sepals s was greatly thickened, and the petals and stamens were displaced in consequence.

It is curious to observe in many of these cases that the transposed organ not only occupies the place of a suppressed or abortive organ, but frequently assumes its colour, and, to some extent, its function. This has been alluded to in the case of the leaf of Gesnera (see p. 88) and in Orchids this replacement seems to be very common; thus, in addition to the cases before mentioned, in a flower of an Odontoglossum, for which I am indebted to Professor Oliver, the two lateral sepals were united together and occupied the position of the labellum, which was absent. A similar occurrence happens occasionally in Lycaste Skinneri, thus recalling the structure of Masdevallia, where the labellum is normally very small. The arrangement in Lycaste may thus be symbolised:

[Transcriber's note: The underscores represent a horizontal curly brace in the original.]

the + indicating the position of the absent labellum.

Cases of this kind are the more interesting from their relation to the fertilization of these flowers by insects; it seems as though, when the labellum, which performs so important an office in attracting and guiding insects, is deficient, its place is supplied by other means.

Displacement of the parts of the flower from elongation of the receptacle is a not infrequent teratological occurrence, resulting sometimes in the conversion of the verticillate into the spiral arrangement. Instances of this are cited under Elongation, Prolification, &c. In this place it is merely necessary to refer to a curious circumstance that is met with in some double flowers, owing to this separation of some parts of the flower and the cohesion or adhesion of others. Thus, in some double flowers of Primula sinensis and in the Pea (Pisum sativum), I have seen a gradual passage of sepals to petals, so that the calyx and corolla formed one continuous sheet, winding spirally around the central axis of the flower, after the fashion of a spiral tube.[98]

Displacement of the carpels arises from one or other of the causes above alluded to, and when suppression takes place in this whorl it generally happens that the place of the suppressed organ is occupied by one of the remaining ones, which thus becomes partially dislocated.

Displacement of the placentas and ovules is a necessary result of many of the changes to which the carpels are subject. The disjunction or dialysis of the carpels, for instance, frequently renders axile placentation marginal. Moreover, it frequently happens, when the carpels become foliaceous and their margins are disconnected, that the ovules, in place of being placed on the suture, or rather on the margins of the altered carpel, are placed on the surface of the expanded carpel. Thus, in some double flowers of Ranunculus Ficaria that came under the writer's notice the carpels were open, i.e. disunited at the margins, and each bore two imperfect ovules upon its inner surface a little way above the base, and midway between the edges of the carpel and the midrib, the ovules being partly enclosed within a little depression or pouch, similar to the pit on the petals. On closer examination the ovules were found to spring from the two lateral divisions of the midrib, the vascular cords of which were prolonged under the form of barred or spiral fusiform tubes into the outer coating of the ovule. In this instance, then, the ovules did not originate from the margins of the leaf, nor from a prolonged axis, but they seemed to spring, in the guise of little buds, from the inner surface of the carpellary leaf.[99]

The occurrence, also, of different forms of placentation in different flowers on the same plant is no unusual thing in malformed flowers; thus, in double flowers of Saponaria officinalis I have met with sutural, parietal, and free central placentation in the same plant.[100]

Professor Babington describes in the 'Gardeners' Chronicle,' 1844, p. 557, a curious flower of Cerastium, in which, in addition to other changes, the five carpellary leaves "were partially turned in without touching the placenta, which bears a cluster of ovules, and is perfectly clear of all connection with those partitions" (fig. 51). See also Lindley, 'Veg. Kingdom,' p. 497.

M. Baillon[101] records flowers of Bunias, some with ovules on the margins of the carpels, others with a central branch bearing the ovules; hence he concludes very justly that no fair inference can be drawn from these facts as to the normal placentation of CruciferÆ.

The same excellent observer has recorded the occurrence of free central placentation in malformed flowers of Trifolium repens.[102]

In malformed flowers of Digitalis the change from axile to parietal placentation may often be seen. Mr. Berkeley describes an instance of this nature where the placentas were strictly parietal, and therefore receded from the distinctive characters of the order, and approximated to those of GesneraceÆ.

The same author alludes to certain changes in the same flower where two open carpels "were soldered together laterally, as was clear by the rudiments of two styles, the placenta being produced only at the two united edges, the outer margins remaining in the normal condition. This may possibly tend to the explanation of some cases of anomalous placentation, for the only indication of the true nature of the placentation is afforded by the two rudimentary styles, in the absence of which the spongy receptacle of the seeds must have been supposed to spring from the medial nerve."

In other cases the placentas were parietal above, but axile at the base of the capsule, a striking instance of the facility with which axile placentation becomes parietal, the change being here effected by the prolongation of the axis, and the formation on it of a second whorl of carpellary leaves.

In double flowers of PrimulaceÆ similar alterations in the placentation may often be observed. I have seen in Primula sinensis sutural, parietal, axile, and free central placentation all on the same plant; nay, even in the same capsule the ovules may be attached in various ways, and transitions from one form of placentation to another are not infrequent. The late Professor E. Forbes describes[103] an instance of true foliar and true axile placentation in the same flower in Vinca minor.

These and many similar changes, which it is not necessary further to allude to, are not so much to be wondered at when it is borne in mind how slight an alteration suffices to produce a change in the mode of placentation, and how frequent is the production of adventitious buds or of foliar outgrowths, as may be seen in the sections relating to those subjects and to Substitutions.

It will be remembered, also, how, in certain natural orders, under ordinary circumstances, considerable diversity in placentation exists, according as the margins of the carpels are merely valvate or are infolded so as to reach the centre. Often this diversity is due merely to the changes that take place during growth; thus, the placentation of CaryophylleÆ, CucurbitaceÆ, PapaveraceÆ, and many other orders, varies according to the age of the carpel, and if any stasis or arrest of development occurs the placentation becomes altered accordingly.

It is not necessary, in this place, to enter into the question whether the placenta is, in all cases whatsoever, a dependence of the axis, as Payer, Schleiden, and others, have maintained, or whether it be foliar in some cases, axial in others. This question must be decided by the organogenists; teratologically, however, there can be no doubt that ovules may be formed from both foliar and axial organs, and, moreover, that, owing to the variability above referred to, both in what are called natural and in what are deemed abnormal conditions, it can rarely happen that any safe inferences as to the normal or typical placentation of any family of plants can be drawn from exceptional or monstrous formations.

On the subject of placentation the following authors may be consulted:

CHAPTER II.
PROLIFICATION.

Moquin-Tandon and other writers have classed the production of buds in unwonted situations under the head of multiplication, but, as the altered arrangement is of graver import than the mere increase in number, it seems preferable to place these cases under this heading rather than under that of alterations of number.

The adventitious bud may be a leaf-bud or a flower-bud; it may occupy the centre of a flower, thus terminating the axis, or it may be axillary to some or other of its component parts, or, again, it may be extra-floral. In this last case the prolification is of the inflorescence, and is hardly distinguishable from multiplication or subdivision of the common flower-stalk. In accordance with these differences we have median, axillary, and extra-floral prolification, each admitting of subdivision into a leafy or a floral variety, according to the nature of the adventitious bud. Under the head of each variety certain special peculiarities are noticed, but it may here be advisable to add a few general remarks on the subject.

Axillary prolification is a much less frequent malformation than the median form. If only the number of orders and genera be reckoned, the truth of this statement will be scarcely recognised; but if individual cases could be estimated, the difference in frequency between the two would be very much more obvious. This may, perhaps, be explained by the fact that the branch has a greater tendency to grow in length than it has to develop buds from the axils of the leaves. The flower is admitted to be homologous with the branch, and it is also known that, up to a certain time, the branch-bud or leaf-bud and the flower-bud do not essentially differ.[104] At a later stage the difference between the two is manifested, not only in the altered form of the lateral organs in the flower-bud, but in the tendency to an arrest of growth, thus limiting the length of the central axial portion. Now, in prolified flowers the functions and, to a considerable extent, the appearance of a leaf-bud or of a branch are assumed, and with them the tendency to grow in length is developed. Median prolification, therefore, in this sense, is a further step in retrograde metamorphosis than is the axillary form. To grow in length, and to produce axillary buds, are alike attributes of the branch; but the former is much more frequently called into play than the latter; for the same reason, median prolification is more common than the axillary form. This is borne out by the frequency with which apostasis, or the separation of the floral whorls one from another, to a greater degree than usual, is met with in prolified flowers.

In both forms the adventitious growth is much more frequently a flower-bud or an inflorescence than a leaf-bud or a branch. This may be due to the position of the flowers on a portion of the stem of the plant especially devoted to the formation of flower-buds, to the more or less complete exclusion of leaf-buds, i.e. on the inflorescence. This conjecture is borne out by the comparative rarity with which prolification has been observed in flowers that are solitary in the axils of the ordinary leaves of the plant. If the lists of genera appended hereto be perused, it will be seen that nearly all the cases occur in genera where the inflorescence is distinctly separated from the other branches of the stem. In direct proportion, then, to the degree in which one region of the axis or certain branches of a plant are devoted to the formation of flower-buds to the exclusion of leaf-buds, is the frequency with which those flowers become affected with floral prolification.

Flowers produced upon indefinite inflorescences are liable to be affected with either form of prolification more frequently than those borne upon definite inflorescences. Prolification in both varieties is also more frequently met with in branched inflorescences than in those in which the flowers are sessile; but the degree of branching seems less material, inasmuch as this malformation is more commonly recorded as occurring in racemes than in the more branched panicles, &c. From the similar arrest of growth in length, in the case of the flower, to that which occurs in the stem in the case of definite inflorescence, it might have been expected that axillary prolification would be more frequent in plants having a cymose arrangement of their flowers than in those whose inflorescence is indefinite; such, however, is not the case. The reason for this may be sought for in the lengthening of the floral axis, so common in prolified flowers—a condition the reverse of that which happens in the case of definite inflorescence.

Median prolification occurs frequently in double flowers; the axillary variety, on the other hand, is most common in flowers whose lateral organs have assumed more or less of the condition of leaves. The other coincident changes are alluded to elsewhere or do not present useful points of comparison, and may therefore be passed over.

Prolification of the inflorescence.—This consists in the formation of leaf-buds or of an undue number of flower-buds on the inflorescence. It must be distinguished from virescence, or the mere green colour of the floral organs, and from chloranthy, in which all or the greater portion of the parts of the flower are replaced by leaves. Prolification is, in fact, a formation of supernumerary buds, leafy or floral, as the case may be, these buds being sessile or stalked, the ordinary buds being not necessarily changed. Prolification of the inflorescence, like the other varieties, admits of subdivision, not only according to the foliar or floral nature of the bud, but according to its position, terminal or median and lateral.

Terminal prolification of the inflorescence, whether leafy or floral, is hardly to be looked upon in the light of a malformation[105] seeing that a similar condition is so commonly met with normally, as in Epacris, Metrosideros, Bromelia, Eucomis, &c., wherein the leafy axis projects beyond the inflorescence proper; or as in Primula imperialis, in which plant, as also in luxuriant forms of P. sinensis, tier after tier of flowers are placed in succession above the primary umbel. Nevertheless, when we meet with such conditions in plants which, under ordinary circumstances, do not manifest them, we must consider them as coming under the domain of teratology.

Median foliar prolification of the inflorescence is frequently met with in ConiferÆ, and has of late attracted unwonted attention from the researches of Caspary, Baillon, and others, on the morphology of these plants. The scales and bracts of the cone in these abnormal specimens frequently afford transitional forms of the greatest value in enabling morphologists to comprehend the real nature of the floral structure. It would be irrelevant here to enter into this subject; suffice it merely to say that an examination of very numerous specimens of this kind, in the common larch and in Cryptomeria Japonica, has enabled me to verify nearly the whole of Caspary's observations. A similar prolongation of the axis occurred in some of the male catkins of Castanea vesca, each of which had a tuft of small leaves at their extremity. In the common marigold and in Lotus corniculatus I have also seen instances of this kind. Kirschleger[106] describes a tuft of leaves as occurring on the apex of the flowering spike after the maturation of the fruit in Plantago, and a similar growth frequently takes place in the common wallflower, in Antirrhinum majus, &c. In cases where a renewal of growth in the axis of inflorescence has taken place after the ripening of the fruit, the French botanists use the term recrudescence, but the growth in question by no means always occurs after the ripening of the fruit, but frequently before. Professor Braun cites the case of a specimen of Plantago lanceolata, in which the spike was surmounted by a tuft of leaves and roots, as well as a still more singular instance in Eryngium viviparum, in which not only did particular branches terminate in rosettes of leaves provided with roots, but similar growths proceeded from the heads of flowers themselves. Baron de MÉlicoq[107] gives a case in Primula variabilis, in which at the top of the flower-stalk, in the centre of six flowers, was placed a complete plant in miniature, having three leaves, from the axil of one of which proceeded a rudimentary flower. Mr. W. B. Jeffries also forwarded me a polyanthus (fig. 52) in which the peduncle was surmounted by a small plant, forming a crown above the ordinary flower-stalk, just as the crown of the pineapple surmounts that fruit. A similar instance was exhibited at the Scientific Committee of the Horticultural Society on July 11th, 1868, by Mr. Wilson Saunders; the species in this case was P. cortusoides. To Mr. R. Dean I am indebted for a similar proliferous cyclamen, which seems similar to one mentioned by Schlechtendal.[108] This author alludes to an analogous circumstance in the inflorescence of Cytisus nigricans, where, however, the change was not so great as in the preceding cases. The instances just cited all occur in plants having an indefinite form of inflorescence; but the production of a tuft of leaves or of a leafy shoot above or beyond the inflorescence is not confined to plants with this habit of growth, for Jacquin figures and describes an instance of this nature in the cymose flower-stems of a Sempervivum. "Hi racemi," says he, "ultra flores producuntur in ramos, foliosos duo bifidos qui tandem trium unciarum longitudinem adepti fuerunt."[109]

Fig. 52.—Inflorescence of Polyanthus, bearing a tuft of leaves at the top of the scape intermixed with the flowers.

Median floral prolification of the inflorescence, wherein a new inflorescence projects beyond the primary one, is not uncommon in plants having their flowers arranged in close heads or umbels, as in the common wild celery and other UmbelliferÆ.[110] I have also met with it in Trifolium repens, in the umbellate variety of the common primrose, and in the scarlet geranium. Engelmann cites it in Triticum repens, RoËper in Euphorbia palustris.[111]

Lateral foliar prolification of the inflorescence is of more common occurrence than the preceding. I have met with it, amongst other plants, frequently in Brassica oleracea, Pelargonium zonale, Scabiosa, Bellis, and many other composites, also in LeguminosÆ, e.g. Lupinus, Trifolium, Coronilla, &c. Prof. Oliver forwarded me a specimen of Euphorbia geniculata in which, in addition to other changes, there was a series of stalked buds bearing tufts of green scales, but without any trace of stamens or pistil; these adventitious buds occurred within the ordinary involucre of the plant, between it and the stamens. The pistil was unaffected in some cases, while in some others it was entirely wanting, the gynophore being surmounted by a cup-like involucre, divided into three acutely pointed lobes, each with a midrib; these encircled a series of stalked involucels, as before, and among which were scattered a few stamens, some perfect, others partially frondescent.

In a specimen of Scrophularia nodosa examined by me one of the lateral buds on each of the cymes was represented, not by a flower, but by a tuft of leaves, the other buds being unchanged. As the inflorescence was much contracted in size, the appearance of the whole plant was greatly changed.

Many of the instances of so-called viviparous plants, e.g., Polygonum viviparum, may be cited under this head.[112] Many species of Allium, Lilium, Saxifraga, Begonia, Achimenes, normally produce leaf-buds or bulbs in the inflorescence; so, too, leafy shoots are sometimes found in Alisma natans, Juncus uliginosus, Chlorophytum Sternbergianum, &c. As an accidental occurrence, a similar thing has been noticed in Lychnis coronaria, Phaius grandifolius, Oncidium cebolleta, Epidendrum elongatum,[113] &c. &c.

Here, too, may be mentioned those cases wherein a leaf-bud is found upon the surface of the so-called inferior ovary; generally a leaf only is found, but a leaf-bud may also originate in this situation, and in either case the inference is that the ovary is, in part at least, made of the dilated and hollowed axis. Leaves may occasionally be found in this way on the so-called calyx-tube or on the inferior ovaries of roses, pears, apples, Pereskia, CratÆgus tanacetifolia, &c.

The fruits of Opuntia Salmania and of O. fragilis ('Bull. Soc. Bot. France,' vol. i, p. 306; vol. v, p. 115) have been observed to form small fruit-like branches around their summits. This circumstance is more fully treated of in the succeeding chapter relating to Heterotaxy.

Lateral floral prolification of the inflorescence.—This, which is termed by Engelmann Ecblastesis foliorum sub floralium,[114] is much the most common of all these deviations, and it is met with in every degree, from the presence of a single supernumerary flower in the axil of a bract to the existence of a small cluster or panicle of such flowers.

It is common in the Anemone coronaria and hortensis, also in the common scarlet Pelargonium (fig. 53). It has been frequently recorded in Poterium sanguisorba, and in Sanguisorba officinalis, and is especially common in UmbelliferÆ, DipsacaceÆ, and CompositÆ; a familiar illustration in the latter order is afforded by the hen-and-chicken daisy. In some species of CompositÆ, indeed, it is a normal and constant occurrence, while in other cases, such as Filago germanica, usually described as proliferous, there is not, strictly speaking, any prolification, for the branching of the stalk takes place below the inflorescence, and the branches originate from the axils of ordinary leaves, not from the floral leaves or bracts. Convolvulus Sepium is very commonly subject to the production of flower-buds from the axils of the floral leaves. The several species of Plantain (Plantago) seem very liable to this and similar changes. Schlechtendal[115] gives a summary of the various kinds of malformation affecting the inflorescence in Plantago, and divides them into five groups, as follows:—1st, bracteate, wherein the inferior bracts are quite leaf-like, as is frequently seen in Plantago major. 2nd, roseate; bracts leafy in tufts or rosettes, without flowers, as in the so-called rose plantain, common in old-fashioned gardens in this country. 3rd, polystachyate; spike-branched, bearing other spikes in the axils of the bracts, as in P. lanceolata, P. maritima, &c. 4th, proliferous, where the flower-stalk bears a rosette, a spike, or a head with other rosettes. 5th, paniculate, in which the inflorescence has become a much-branched pyramidal panicle, covered with little bracts, and with very rudimentary flowers.[116] The first two groups belong rather to frondescence of the bracts; but with regard to the whole of them it will easily be surmised that intermediate forms occur, linking one group to the other, and defying exact allocation in either. Thus, in the borders of richly cultivated fields in the neighbourhood of London I have frequently gathered specimens of Plantago major with a branched spike provided with large leafy bracts, the branches of the spike being but little less in diameter than the ordinary single spike. These specimens would therefore seem to be intermediate between Schlechtendal's bracteate and polystachyate divisions. Wigand[117] also describes an anomalous specimen of Plantago major similar to those just mentioned, but having small lateral spikes in place of large ones. The instance quoted from Professor Braun would fall under the roseate section, as would also that of Kirschleger, though we are expressly told that the tuft of leaves in this last case was not developed until after the ripening of the seed-vessel. One of the characters of the roseate group, according to Schlechtendal, is the absence of flowers, but most persons who have had the opportunity of watching the growth of the rose plantain must have observed the occasional production of flowers, sometimes stalked, in the axils of the leafy bracts, and at the same time have noticed that the internodes become elongated, so that an approach is made to the ordinary spike-like form of the inflorescence. The proliferous group would include such specimens as that of P. lanceolata mentioned by Dr. Johnston,[118] wherein were several spikes, some sessile, others stalked and pendent, the whole intermixed with leaves and disposed in a rose-like manner. I have myself gathered specimens of this nature, occurring in the same plant, at Shanklin, Isle of Wight (fig. 56).

The instances wherein flower-buds originate from the surface of an inferior ovary, as in those cases where the top of the stem is dilated so as to form part of the fruit, would be properly classed under the head of prolification of the inflorescence. As, however, there is still some difference of opinion as to the correct morphological interpretation to be put on some of these cases, it has been thought better to include them under the head of heterotaxy than of prolification.

Some of the cases of prolification of the inflorescence resulting in a branching of an ordinarily simple inflorescence, as in Reseda luteola (fig. 57), might equally well be placed with fission or multiplication of the axile organs. Branched spikes of this character are not so common among Orchids as might be expected. Professor Reichenbach enumerates a few instances in the Report of the International Botanical Congress of London, 1866, p. 121, and the same author gives an illustration in his 'Orchidographia Europoea,' tab. 150.

In Grasses, as indeed in other plants with a spicate inflorescence, this change occurs not unfrequently. The common Ray Grass (Lolium) is especially subject to the change in question, and among cultivated cereals, maize and wheat occasionally show this tendency to subdivision. One variety of the latter grain is cultivated in hot countries under the name of Egyptian wheat—Triticum vulgare, var. compositum.

Prolification of the inflorescence has been most frequently observed in the following genera:

In addition to the papers already cited the following works may be consulted with reference to prolification of the inflorescence:

Prolification of the flower.—In the preceding sections the formation of adventitious buds of a leafy or floral nature on the inflorescence has been considered. A similar production of buds may take place in the flower itself, either from its centre or from the axil of some of its constituent parts. Prolification of the flower is therefore median or axillary, and the adventitious bud itself may be of a leafy or a floral nature.

Median leafy prolification.—In this malformation the centre of the flower is occupied by a bud or a branch; the growing point or termination of the axis which ordinarily ceases to grow after the formation of the carpels, takes on new growth. This is well shown in the accompanying illustration (fig. 58), representing the thalamus of a strawberry prolonged beyond the fruits into a small leaf-bearing branch.

In other cases the carpels are entirely absent and their place is supplied by a leafy shoot as in a species of Verbascum, which came under my own observation. In this case the petals were virescent, and the stamens and pistils were entirely absent, hence in truth, the so-called flower more nearly resembled a branch. In a flower of a May Duke cherry, for which I am indebted to Mr. Salter, there was a gradual change from the floral to the foliar condition; thus there were five distinct lanceolate sepals, the arrangement of whose veins betokened that they were leaf-sheaths rather than perfect leaves, ten petals partly foliaceous and sheath-like as to their venation, one of them funnel-shaped, but whether from dilatation or cohesion of the margins could not be determined. The stamens were eight or ten in number, their connectives prolonged into foliaceous or petaloid appendages, so that the filament represented the stalk of the leaf. The pistil was entirely absent and its place was supplied by a branch with numerous perfectly formed stipulate leaves.

Some flowers of Anagallis arvensis described by Dr. Marchand[119] are so interesting and show so well the gradual stages by which this malformation is arrived at, that it is desirable to cite the summary of Dr. Marchand's researches as given in the 'Gardeners' Chronicle' by Mr. Berkeley, taking that instance first in which the parts of the flower departed least from the normal condition, and then the others in their proper order. In all the parts there was a greater or less tendency to assume a green tint; in some they were entirely green, in others the brighter colours were confined to the more recently developed parts.

"1. In the first case then, the sepals and petals were in their normal position, though rather more dilated than usual; the anthers were fertile, the principal change existing in the ovary, the upper part of which was wanting, so that the ovules were exposed seated on the central placenta.

2. In the next step the calyx, more developed than usual, was separated from the corolla by a long peduncle, and the ovary, which was ovate, contained instead of a placenta a sort of plumule or young shoot.

3. In this case the corolla and calyx were distant from each other; there was no trace of stamens, but the axis was continued from the centre of the corolla, and ended in a leaf-bud.

4. The calyx and corolla nearly as before, but instead of stamens a whorl of little leaves was developed, in the centre of which the axis was continued, bearing at its tip two whorls of leaflets, alternately three and three.

5. In this case two out of the five stamens were normal, the other three changed into leaves, showing clearly the origin of the leaflets, in the last case, which took the place of the stamens.

6. The ovary varied in different flowers. In some the placenta was crowned with ovules; in others the ovules were replaced by a single whorl of leaflets; in others there was every shade of change from ordinary ovules to perfect leaflets; while in others, again, every ovule was converted into a leaf with a long petiole.

7. In these flowers shoots were developed in the axils of the sepals, or on the face of the petals between the point of their insertion and that of the stamens, and, what is most curious, in the interior of the ovaries round the foot of the placenta.

8. Here, again, a very singular condition presented itself: the calyx and corolla separated from each other, the stamens partly developed, the axis continued beyond the corolla, branched and bearing normal leaves so as exactly to resemble an ordinary stem, while in consequence of the calyx and corolla being bent down to the ground, adventitious roots were developed from the axis on the under side above each of them. In another case, where the calyx and corolla were approximated, the ovary was open above, and sent out six shoots from within, perfectly developed, clearly representing the central placenta and five axile buds, and each giving out a number of adventitious roots at its base."

In other genera of the same order (PrimulaceÆ) an extension of the placenta into a leafy branch has been observed, as in Lysimachia, where in one case the prolonged placenta was removed and struck as a cutting.[120]

In EricaceÆ too, the axile placenta has been seen ovuliferous at the base and prolonged above into a leafy branch.[121]

Median floral prolification.—This is of more frequent occurrence than the preceding. The prolonged axis is more frequently terminated by a flower-bud than by a leaf-bud, though it must be remarked, that the lengthened and protruded stem frequently bears leaves upon its sides, even if it terminate in a flower, and thus the new growth partakes of a mixed leafy and floral nature. Instances of this kind have long been familiar to observers, and have always excited attention from the singularity of their appearance. In one of the old stained-glass windows, apparently of Dutch manufacture, in the Bodleian Picture Gallery at Oxford, is a representation of a Ranunculus affected with median floral prolification.[122] In pinks the affection is not unfrequently met with. Fig. 60 shows an instance of the kind copied from Schotterbec.

A singular instance of prolification in the central flower of one of the verticillasters of Phlomis fruticosa fell under my own notice; it was a case wherein the calyx was torn on one side, and one of its lobes had become petaloid. Between the calyx and the corolla were three or four spathulate, hairy, bract-like organs; the corolla and stamens were unchanged; but in place of the usual four-lobed ovary there was a single carpel with a basilar style, terminated by a forked stigma. Occupying the place of the other lobes of the pistil was an oblong woolly flower-bud, consisting of calyx, corolla, and stamens, but with no trace of pistil. I have been unable to find recorded any instance of malformation among Labiates or Borages at all similar to this. It differed from most other examples of prolification in that the axis was not prolonged, the adventitious bud occupying precisely the position of the three lobes of the ovary that were absent. The sole remaining carpel had a style and a stigma as perfect in appearance as though the pistil had been complete.

Certain families of plants present this deviation from their ordinary structure with greater frequency than others: the following orders seem to be the most frequently affected by it: RanunculaceÆ, CaryophyllaceÆ, RosaceÆ; while it is commonly met with in ScrophulariaceÆ, PrimulaceÆ and UmbelliferÆ. Of genera which seem peculiarly liable to it may be mentioned the following: Anemone, Ranunculus, Cheiranthus, Dianthus, Dictamnus, Daucus, Rosa, Geum, Pyrus, Trifolium, Antirrhinum, Digitalis, Primula.

A reference to the subjoined list of genera affected by this malformation, and the knowledge of its comparatively greater frequency in some than in others of them, will show that it is more often met with in plants having an indefinite form of inflorescence than in those having a definite one. The change may affect some only, or the whole of the flowers constituting an inflorescence; and though it is by no means a constant occurrence, it very frequently happens that the central or terminal flower in a definite inflorescence is alone affected, the others remaining in their ordinary condition, as in pinks (Dianthus); and in the indefinite forms of inflorescence, it is equally common that the uppermost flower or flowers are the most liable to be thus affected.

In those plants which present this deviation from the ordinary condition with the greatest frequency, it often happens that the axis is normally more or less prolonged, either between the various whorls of the flower, as in the case of the gynophore, &c., or into the cavity of the carpels, as in the instances of free central placentation. To bear out this assertion, the following instances taken from those genera having definite inflorescence, and which are very commonly affected with prolification, may be cited; thus, in Anemone and Ranunculus the thalamus is prolonged to bear the numerous carpels; in Dianthus there is a marked internode separating the carpels from the other parts of the flower; in PrimulaceÆ central prolification is very common, and this is one of the orders where the placenta seems from the researches of Duchartre and others, to be truly a production of the axis within the carpels;[123] in Thesium also, another genus with free central placenta, this malformation has been found.

So also among plants with indefinite inflorescence, prolification seems very frequently to affect those wherein the axis is normally prolonged; thus it is common in Dictamnus, which plant has an internode supporting the pistil; it is frequent among UmbelliferÆ, where the carpophore may be truly considered an axile production; it is common among RosaceÆ and RanunculaceÆ, in many of which the axis or thalamus is well-marked, and it is by no means infrequent in the flowers of the Orange, where the floral internodes are also slightly elongated; on the other hand, there is no case on record in MagnoliaceÆ, and some other orders where the floral part of the axis is at some point or other elongated; still, on the whole, there can be but little doubt that there is a real relation between prolification and the normal extension of the floral internodes.

Under these circumstances, those instances wherein the parts of the flower become separated one from the other by the elongation of the internodes (apostatis), constitute a lesser degree of the same change, which operates most completely in the formation of a new bud at the extremity of the prolonged axis. Some specimens of Geum rivale (a plant very liable to become prolified) in my possession show this very clearly. In the wild plant the thalamus is elevated on a short stalk; in the abnormal ones the thalamus is simply upon a longer stalk than usual, or in a more advanced stage of the deviation the lengthened thalamus takes the form of a branch provided with leaves and terminated by a flower; it is noticeable, also, in these specimens, that the sepals of the lower flower have assumed entirely the dimensions and appearance of leaves.

Median prolification has occasionally been recorded in flowers that have, in their ordinary condition, but one carpel, as in LeguminosÆ and in SantalaceÆ. In LeguminosÆ, as also in Amygdalus, it would seem as if the adventitious bud were strictly a lateral and axillary production, and moreover that the carpel itself is not strictly terminal but lateral in position, though apparently terminal from the abortion of other carpels. In the only recorded instance that I am aware of, of this malformation affecting the genus Thesium, the pistil was altogether absent, and occupying its place was the new bud or branch.[124]

As the carpels are not unfrequently absent in cases of median prolification, it has been thought that the pistil in such cases was metamorphosed into a stem bearing leaves or flowers. Setting aside the physiological difficulties in the way of accepting such an opinion, an examination of any number of cases is sufficient to refute it; for, as Moquin well remarks, the carpels may frequently be found either in an unaltered condition or more or less modified.

If the pistil be normally syncarpous, its constituent carpels, if present at all in the prolified flower, become disjoined one from the other to allow of the passage between them of the prolonged axis; thus in some malformed flowers of Daucus Carota gathered in Switzerland (fig. 61), not only was the calyx partially detached from the pistil, but the carpels themselves were leaf-like, disjoined, and unprovided with ovules; between them rose a central prolongation of the axis, which almost immediately divided into two branches, each terminated by a small umbel of perfect flowers, surrounded by minute bracts.[125]

Not only are the carpels thus frequently separated one from the other by the prolonged axis, but they undergo commonly a still further change in becoming more or less completely foliaceous, as in the Daucus just mentioned, where the carpels were prolonged into two lance-shaped leaves, whose margins in some cases were slightly incurved at the apex, forcibly calling to mind the long "beaks" that some Umbelliferous genera have terminating their fruits—for instance, Scandix. Dr. Norman, in the fourth series of the 'Annales des Sciences,' vol. ix, has described a prolification of the flower of Anchusa ochroleuca, in which the pistil consisted of two leaves, situated antero-posteriorly on a long internode, with a small terminal flower-bud between them; and numerous similar instances might be cited.

In this place may also be noticed those instances wherein the placenta elongates so much that the pericarp becomes ruptured to allow of the protrusion of the placenta, although this prolongation is not attended by the formation of new buds. Cases of this kind occurring in Melastoma and Solanum have been put on record by M. Alph. de Candolle.[126] This is a change analogous with that which occurs in some species of Leontice or Caulophyllum, as commented on by Robert Brown. See 'Miscellaneous Botanical Works' of this author, Ray Society, vol. i, p. 359.

If the pistil be apocarpous, and the carpels arranged spirally on an elevated thalamus, it then frequently happens that the carpels, especially the upper ones, become carried up with the prolonged axis, more widely separated one from the other than below, and particularly liable to undergo various petalloid or foliaceous changes as in proliferous Roses, Potentilla, &c.

Fig. 62, copied from Cramer, shows an instance of this kind in Delphinium elatum, where not only is the thalamus prolonged, and the carpels separated, but from the axils of some of the latter which have assumed from the disunion of their margins somewhat of the appearance of leaves, other flowering branches proceed—axillary prolification. If, on the other hand, the carpels be few in number, and placed in a verticillate manner, the axis then generally passes upwards without any change in the form or position of the carpels being apparent, as in a proliferous columbine, figured in the 'Linnean Transactions,' vol. xxiii, tab. 34, fig. 5.

When a flower with the ovary naturally inferior or adherent to the calyx becomes prolified, a change in the relative position of the calyx and ovary almost necessarily takes place, the latter becoming superior or detached from the calyx; this has been already alluded to in UmbelliferÆ. In a species of Campanula examined by me, the calyx was free, the corolla double, the stamens with petaloid filaments, and in the place of the pistil there was a bud consisting of several series of green bracts, arranged in threes, and enclosing quite in the centre three carpellary leaves detached from one another and the other parts of the flower, and open along their margins, where the ovules were placed. In other similar instances in the same species of Campanula, the styles were present, forming below an imperfect tube which surrounded the adventitious bud; in another, contrary to what occurs usually in such cases, the ovary was present in its usual position, but surmounted by a bud of leafy scales, enclosed within the base of a tube formed by the union of the styles. A similar relative change in the position of the calyx and the ovary takes place when the CompositÆ are affected with central prolification, or even in that lesser degree of change which merely consists in the separation and disunion of the parts of the flower, but which in these flowers appear to be, as it were, the first stage towards prolification. I owe to the kindness of Professor Oliver a sketch of a species of Rudbeckia? showing this detachment of the calyx from the ovary. In a monstrous Fuchsia that I have had the opportunity of recently examining, the calyx was similarly detached from the ovary simultaneously with the extension of the axis. Here the petals were increased in number and variously modified, the stamens also; while in the centre and at the top of the flower, conjoined at the base with some imperfect stamens, was a carpel open along its ovuliferous margins. Such instances as these seem to be the first stages of a change which, carried out more perfectly, would result in the formation of a new bud on the extremity of the prolonged axis.

In OrchidaceÆ, among which family I have now met with several instances of prolification, the ovary seems usually to be absent. Fig. 63 shows a prolified flower of Orchis pyramidalis in which the perianth was nearly regular, the central portions of the flower absent, and their place supplied by a new miniature raceme. This specimen was forwarded to me by Dr. Moore, of Glasnevin.

As might be expected, it very rarely happens that median prolification occurs without some other deviation in one or more parts of the flower being simultaneously manifested. Some of these changes have been already mentioned, but others are commonly met with, as, for instance, the multiplication or doubling, as it is termed, of the petals; others, though less frequent, are of more interest. Fusion of two or more flowers in association with prolification is especially common in cultivated specimens of Digitalis purpurea; the uppermost flowers of the raceme become fused together so as to form one large, regular, erect, cup-shaped corolla, to the tube of which the stamens are attached, in greater number than ordinary, and all of equal length; the bracts and sepals are confusedly arranged on the exterior of the flower; while in the centre, in the place usually occupied by the pistil, there rises a conical prolongation of the axis, bearing at its outer or lower portion a number of open carpels, provided, it may be, with styles and ovules; these enclose an inner series of scale-like bracts, from whose axils proceed more or less perfect florets; so that in the most highly developed stage a perfect raceme of flowers may be seen to spring from the centre of a cup-shaped regular flower, whose lobes show its compound character. All intermediate stages of this malformation may be found from cases where there is a simple fusion of two flowers with a second verticil of carpels within the outer, up to such cases as those which have been just mentioned. It is worthy of special remark, that in all these cases the flowers at the uppermost part of the raceme are alone affected, and that, in addition to the prolification, there is fusion of two or more flowers, and regularity in the form of the compound corolla and stamens.

The calyx of a prolified flower is either unchanged, or it is modified in harmony with the changes in the central part of the flower. If the ovary be normally superior or free from the calyx, then the latter is comparatively rarely altered; for instance, in proliferous pinks (Dianthus) the calyx is seldom affected, except, indeed, in those instances where the floral axis is prolonged, and produces from its side a successive series of sepals, as in what is called the wheat-ear carnation; but though these instances may be, as I believe, an imperfect degree of prolification, they do not affect the general truth of the above opinion, that the calyx, if it be free from the ovary, is but rarely changed in a prolified flower; but that this is not a universal rule is shown by proliferous flowers of Geum rivale, where the sepals are usually large and leaf-like, as they likewise are frequently in proliferous roses and pears.

Proliferous roses have a special interest, inasmuch as they show very conclusively that the so-called calyx-tube of these plants is merely a concave and inverted thalamus, which, in prolified specimens, becomes elongated (fig. 64) after the fashion of Geum rivale, &c.[127] Occasionally from the middle of the outer surface of the urn-shaped thalamus proceeds a perfect leaf, which could hardly be produced from the united sepals or calyx-tube; a similar occurrence in a pear is figured in Keith's 'Physiological Botany,' plate ix, fig. 12.

The change which the calyx undergoes when flowers with an habitually adherent ovary become prolified, and wherein the calyx is disjoined from the ovary, has been before mentioned, but it may also be stated that, under such circumstances, the constituent sepals are frequently separated one from the other, and not rarely assume more or less of the appearance of leaves, as in proliferous flowers of UmbelliferÆ, CampanulaceÆ, CompositÆ, &c.

As to the corolla, it was long since noticed that prolification was especially liable to occur in double flowers; indeed, Dr. Hill, who published a treatise on this subject, setting forth the method of artificially producing prolified flowers, deemed the doubling to be an almost necessary precursor of prolification;[128] but, though frequently so, it is not invariably the case that the flower so affected is double—e.g. Geum. If double, the doubling may arise from actual multiplication of the petals, or from the substitution of petals for stamens and pistils, according to the particular plant affected. Occasionally in prolified flowers the parts of the corolla, like those of the calyx, become foliaceous, and in the case of proliferous pears fleshy and succulent. There is in cultivation a kind of Cheiranthus? in which there is a constant repetition of the calyx and corolla, conjoined with an entire absence of the stamens and pistils; a short internode separates each flower from the one above it, and thus frequently ten or a dozen of these imperfect flowers may be seen on the end of a flower-stalk, giving an appearance as if they were strung like beads, at regular intervals, on a common stalk. I have seen a similar instance in a less degree in a species of Helianthemum.

The stamens are subject to various changes in prolified flowers; they assume, for instance, a leaf-like or petal-like condition, or take on them more or less of a carpellary form, or they may be entirely absent; but none of these changes seem to be at all necessarily connected with the proliferous state of the flower. Of more interest is the alteration in the position of these organs which sometimes necessarily accrues from the elongation of the axis and the disjunction of the calyx; thus, in proliferous roses the stamens become strictly hypogynous, instead of remaining perigynous. In UmbelliferÆ the epigynous condition is changed for the perigynous, &c.

The condition of the pistillary organs in prolified flowers has already been alluded to. Hitherto those instances have been considered in which either the carpels were absent, or the new bud proceeded from between the carpels. There is also an interesting class of cases where the prolification is strictly intra-carpellary; the axis is so slightly prolonged that it does not protrude beyond the carpels, does not separate them in any way, but is wholly enclosed within their cavity. Doubtless, in many cases, this is merely a less perfect development of that change in which the axis protrudes beyond the carpels. This intra-carpellary prolification occurs most frequently in plants having a free central placenta, though it is not confined to them, as it is recorded among BoragineÆ. A remarkable instance of this is described by Mr. H. C. Watson in the first volume of Henfrey's 'Botanical Gazette,' p. 88. In this specimen a raceme of small flowers was included within the enlarged pericarp of a species of Anchusa. But the most curious instances of this form of prolification are, no doubt, those which are met with among PrimulaceÆ and other orders with free central placentation.

Duchartre, in his memoir on the organogeny of plants with a free central placenta, in the 'Ann. des Sc. Nat.,' 3 sÉr., 1844, p. 290, among other similar instances, mentions two flowers of Cortusa Matthioli, wherein the placenta was ovuliferous at the base; but the upper portion, instead of simply elongating itself into a sterile cone, had produced a little flower with its parts slightly different from those of the normal flowers. M. Alph. de Candolle has likewise described somewhat similar deviations, and one in particular in Primula Auricula, where the elongated placenta gave off long and dilated funiculi bearing ovules, while other funiculi were destitute of these bodies, but were much dilated and foliaceous in appearance.[129] In some flowers of Rhododendron I have observed a similar condition of the ovules, which, moreover, in the primary flowers, were attached to the walls of the carpels—parietal placentation.

In speaking of these as cases of intra-carpellary prolification, it is, of course, impossible to overlook the fact that they differ in degree only from those cases where the lengthened axis projects beyond the cavity of the carpels; nevertheless they seem to demand special notice, because in these particular plants the placenta or its prolongation appears never to protrude beyond the carpels, or at least very rarely. There are, however, numerous instances of such an extension of the placenta and of prolification occurring among PrimulaceÆ in conjunction with the more or less complete arrest of growth of the carpels.[130] An instance of this kind has come under my own notice in a monstrosity of the chinese primrose, in which the carpels were reduced to a hardly discernible rim surrounding an umbel of five rays, each terminated by a small normally constituted flower-bud.

The ovules of a prolified flower are either unaffected, or they occur in a rudimentary form, or, lastly, they may be present in the guise of small leaves.

Under the term prolification of the fruit two or three distinct kinds of malformation appear to have been included. The term seems usually to be applied to those cases where from the centre of one fruit a branch bearing leaves, flowers, or another fruit, is seen to project, as happens occasionally in pears. Now, in many instances, not only the fruit, is repeated, but also the outer portions of the flower, which wither and fall away as the adventitious fruit ripens; so that at length the phenomenon of one fruit projecting from another is produced. It is obvious that this form of prolification in no wise differs from ordinary central prolification. Sometimes some of the whorls of the adventitious flower are suppressed; thus, M. Duchartre describes some orange blossoms as presenting alternating series of stamens and pistils one above another, while the calyces and corollas belonging to each series of stamens and pistils were entirely suppressed.[131] In other cases, doubtless, the carpellary whorl is alone repeated, the other whorls of the adventitious flower being completely absent.

Another condition, apparently sometimes mistaken for prolification of the fruit, is that in which the carpellary whorl becomes multiplied; so that there is a second or even a third series within the outer whorl of carpels. If the axis be at all prolonged, then these whorls are separated one from the other, and produce in this way an appearance of prolification. This happens frequently in oranges, as in the variety called Mellarose.[132]

Moquin has given an explanation of the St. Valery Apples, wherein the petals are sepaloid, the stamens absent, and where there is a double row of carpels, by supposing these peculiarities to be due to "a prolification combined with penetration and fusion of two or more flowers," but it is surely more reasonable to conceive a second row of carpels placed above the first by the prolongation of the central part of the axis. Supposing this view to be correct, the inner calyx-like whorl might be considered either as a repetition of the calycine whorl, or it might be inferred that the corolla was present in the guise of a second calyx.

Moquin-Tandon suggests another explanation—namely, that though the stamens are absent in these curious flowers, at least in their ordinary shape, they are represented by the lower row of carpels, which become, in process of development, fused with the upper or true carpels. If this were so, surely some intermediate conditions between stamen and carpel would occasionally be present; but such does not appear to be the case.[133]

In some of the instances of so-called proliferous pears the carpels would seem to be entirely absent, and the dilated portion of the axis to be alone repeated. Thus, the axis dilates to form the lower fruit without any true carpels being produced, but at its summit a whorl of leaves (sepals) is formed; above these another swelling of the axis takes place also without the formation of carpels, and this, it may be, is terminated in its turn by a branch producing leaves. In these cases there is no true prolification, but simply an extension of the axis. That the outer portion (so-called calyx-tube) of these fruits is really an axile product there can now be little doubt; and, as if to show their axile nature, they occasionally produce leaves from their sides, as before mentioned. Moquin, in the tenth volume of the 'Bulletin of the Botanical Society of France,' p. 73, says that when the case is one of prolification the lower fruit is larger and is formed of a fleshy mass; moreover, the line of demarcation between the fruits is more distinct, and there are traces of the seed-bearing cavity in the interior, and of calycine lobes at the top. On the other hand, if the case be one of hypertrophy merely, the lowermost fruit is the smallest, and there is no trace of seed-bearing cavity nor of sepals. See also under Hypertrophy.

Some other malformations usually referred to prolification of the fruit seem due to branching of the inflorescence, as in Plantago, wheat, maize; or to a simple extension of the axis beyond its ordinary limit, as in some cones of firs, &c. It is obvious that the true fruits in these cases are in no wise affected.

From these considerations it would appear better to abandon the use of the expression prolification of the fruit, as unnecessary where it is really applicable, and as delusive in the numerous other cases where it is employed.

Median prolification of one or other kind has been met with in the following genera:

Axillary prolification is the term applied to those cases wherein one or more adventitious buds spring from the axils of one or more of the parts of the flower. Engelmann makes use of the word ecblastesis to denote the same condition. Both terms are open to the objection that they do not clearly enable us to distinguish prolification occurring within the flower from a similar state originating outside the flower, within the bracts of the inflorescence. This latter condition, called by Moquin-Tandon lateral prolification (see Prolification of the Inflorescence), is as truly axillary as that to which the name is restricted. In consequence of certain peculiarities in the structure of some flowers, to be hereafter alluded to, it is not in all cases easy to decide whether the new growth springs from the interior of the flower, or from the inflorescence beneath the flower.

The accessory bud presents itself as a leaf-bud, a branch, a flower-bud, or a miniature inflorescence; it may be sessile, but is far more frequently stalked, and in more than half the number of cases it is a flower-bud or an inflorescence. There may be one or more of these buds; if two only, then they are usually placed directly opposite one to the other, on the opposite sides of the flower.

It will be seen, from the appended list, that the orders and genera in which this description of adventitious growth occurs most frequently are the following:—CruciferÆ, especially the genus Brassica; CaryophyllaceÆ, e.g. Dianthus; ResedaceÆ; LeguminosÆ, e.g. Melilotus, Trifolium, &c.; RosaceÆ, e.g. Rosa, Potentilla, &c.; UmbelliferÆ, and CampanulaceÆ. For the most part, these are groups also peculiarly liable to central prolification.

All the parts of the flower may be thus affected; but, as might have been anticipated from the foliaceous nature of the sepals, the new bud usually arises from within the axil of one of those organs. Next in frequency to the calyx, the pistil is subjected to this change—the carpels in such a case being disunited and leaf-like. The petals rank next, and lastly the stamens; these latter, indeed, are usually, but not invariably, absent, the new growth occupying their position. Hence it may well be that when such is the case, there is no real axillary prolification, but rather the substitution of a bud for a stamen. Generally, however, the position of the accessory bud is such that it may properly be referred to the axil of an undeveloped or rudimentary stamen.

The largest number of instances of this malformation, not merely generically, but also individually, occurs in plants the members of whose floral whorls are not united one to the other; thus, it is far more common in polypetalous plants than in gamopetalous ones. In the prolified flowers belonging to the latter group, the sepals, if not actually uncombined, are only united for a short distance. The same relationship, but in a much less degree, exists in the case of median prolification, as that aberration is likewise most commonly met with in polypetalous flowers. Another feature of interest is the rarity with which axillary prolification is found in irregular gamopetalous blooms. It may be that the irregular and comparatively excessive growth in some parts of these flowers, as compared with others, may operate in checking any luxuriant tendency in other directions.

As in the case of median prolification, plants having an indefinite inflorescence are more liable to be affected with ecblastesis than those having a definite one. The degree of branching of the inflorescence may be noticed, as this deformity is far more common in plants whose peduncles are branched than in those which have either a solitary flower or an unbranched flower-stalk. More than two thirds of the entire number of genera cited as the subjects of this malformation have a branched inflorescence of some form or other; and about two thirds of the cases occur in genera having some form of indefinite inflorescence. If individual instances could be accurately computed, the proportion would be even higher.

Fully three fourths of the entire number of genera recorded as occasionally the subjects of this irregularity possess in their usual state some peculiarity of the thalamus; for instance, in about a third of the whole number of genera the thalamus is more or less prolonged between some or other of the floral whorl, e.g. CaryophyllaceÆ, Potentilla, Anemone, Dictamnus, UmbelliferÆ, &c. About one fourth of the genera have numerous stamens or numerous carpels, or both, springing naturally from the thalamus. In others (about one sixth) the thalamus is enlarged into a disc, or else presents one or more glandular swellings, e.g. Reseda, NymphÆa, CruciferÆ. In the last-named family, as has been already remarked, prolification is very common. It would be interesting to ascertain precisely what part of an inflorescence is most liable to this affection; but as information on this point is but rarely given in the records of these cases, I can only give the results of my own observations, which go to show that, in a many-flowered inflorescence, those flowers at the outside, or at the lower portion, seem to be more frequently the subjects of this change than those situated elsewhere. This may probably be accounted for by the fact that the malformation is met with most generally in plants with an indefinite form of inflorescence, and therefore the lowermost or outermost flowers are most fully nourished; the upper flowers being in a less advanced condition, the change is more likely to be overlooked in them; or it may be that from the unusual luxuriance in the lower flowers, the upper ones may be either present in their ordinary condition, or may be (as indeed frequently happens) stunted in the size and proportion of their several parts.

Axillary foliar prolification of the flower.—The formation of an adventitious leaf-bud in the axil of any of the parts of the flower is not of such common occurrence as the development of a flower-bud in similar situations, nor is it so frequent as median foliar prolification. I have seen leafy shoots proceeding from the axils of the sepals in the flowers of Brassica, and a similar occurrence has been noticed in Caltha palustris, Herreria parviflora, and other plants. Dr. Marchand's flowers of Anagallis, previously referred to at p. 117, showed good illustrations of this occurrence, as also some specimens described by Kirschleger in A. phoenicea.[134] Steinheil has figured and described[135] a flower of Scabiosa in which there was an adventitious formation of leafy shoots in the axil of the outer calyx. In some flowers, such as Convolvulus, Anemone, &c., the exact nature of the sub-floral leaves is uncertain, i.e. it is open to doubt whether the organs in question are bracts or leaves pertaining to the inflorescence, or whether they are really parts of the flower. When leafy shoots are formed in the axils of such organs, the adventitious growth may be referred to extra-floral prolification, prolification of the inflorescence that is, or to axillary prolification, according to the view taken of the real nature of the sub-floral leaves. So far as the mere occurrence of prolification is concerned, it is not very material which view be adopted. The same remark applies to cases where leaf-buds occur on the outer surface of inferior ovaries, as in RosaceÆ, PomaceÆ, Philadelphus, or Tetragonia expansa, as elsewhere mentioned.

It would seem more consistent with the general arrangements of parts, that the adventitious buds should be formed more frequently outside than within the flower proper.

Knight[136] figures and describes the occurrence of small tubers or fleshy leaf-buds in the axils of the sepals of a potato, a curious illustration of the real morphological nature of the tuber.

Axillary floral prolification of the flower.—As already stated, this is of more common occurrence than the formation of a leaf-bud in a similar situation. Any of the parts of the flower may thus subtend a flower-bud, though probably the new buds more frequently originate in the axils of the sepals than in the other whorls. In CruciferÆ the change in question is, relatively speaking, very common. In cauliflowers and broccoli I have frequently met with stalked flowers proceeding from the axils of the sepals, so also in some fuchsias I have seen a ring of stalked flower-buds alternating with the petals, which, together with the stamens and pistil, remained unaffected. The number of parts in the supernumerary structures is generally less than the normal flowers.

In Mr. Herbert Spencer's 'Principles of Biology,' part iv, p. 37, are figured and described some monstrous inflorescences in Angelica and other UmbelliferÆ, from which, amongst other things, the author draws the conclusion that there is no absolute distinction between leaf and branch. Without staying for the moment to discuss this matter, it may here be said that the Umbellifers in question apparently owe their peculiarities rather to axillary prolification within the flower, or to prolification of the inflorescence, than to an actual transformation of a flower or any portion of a flower into an umbellule.[137]

In the 'Gardeners' Chronicle,' 1855, p. 551, an instance is figured of the production of a supernumerary flower proceeding from the axil of a stamen in a species of NymphÆa (fig. 65). The ovary in this case was wanting, but in its place was a tuft of small leaves. It is curious that among Dr. Kirk's drawings of east tropical African plants now at Kew, there should be one representing a precisely similar state of things. The species in both instances was NymphÆa Lotus, or a cultivated variety of it.

M. Wesmael[138] describes a very singular case of what appears to have been referable to axillary prolification in the flowers of Carex acuta. The rachillus is described as prolonged through the utricle by the side of the stigmas, bearing on its side a bract, then a secondary utricle, from the axil of which sprung a short stem surmounted by an ovary. Wigand, 'Flora,' 1856, mentions a similar change in Carex glauca. In this instance the base of the female inflorescence bore lateral spikes, which projected from the utricles; some of these adventitious spikes were female, others female below and male above, others, again, wholly male.

Various changes in the form and arrangement of the several floral whorls accompany axillary prolification; some of these affect the particular organ or organs implicated, and these only, while in other cases some other parts of the flower likewise undergo modification. The changes most commonly met with are such as may be classed under Goethe's theory of retrograde metamorphosis; for instance, if a supplementary bud be developed in the axil of a sepal, that sepal is likely to be more than ordinarily leaf-like in appearance. The dislocation of the affected sepal from its fellows is a very frequent occurrence; in cases of this kind the detached sepal is placed below the others, thus approximating, in position as well as in function, to the bracts. In some of the instances of proliferous pears, on which I shall have occasion to comment, the sepals are described as sharing in the succulent character of the fruit.

The petals, under such circumstances, often exist in the guise of sepals or of small leaves; and instances are recorded wherein the place of the calyx and corolla was supplied by a succession of overlapping green scales, from the axils of which the new buds arose. M. Germain de Saint Pierre records such a case in Trifolium repens, wherein the calyx and corolla were replaced by overlapping scales, in the axils of each one of which arose a flower; above there was a row of stamens, and in the centre a pistil in the guise of a trifoliate leaf.[139] Such instances seem to afford an extreme degree of a more common change, viz., the diminished size and contracted appearance of the sepals and petals when affected with axillary prolification. They have also a close relationship to such developments as we see in the wheat-ear carnation, in certain species of the genus MÆsa and others, wherein the calyx is repeated over and again, to the partial or complete suppression of the other parts of the flower. All these cases may be in part explained by the operation of the principle of compensation.

So far as the androecium is concerned, the stamens either remain unaltered, or they are present in a more or less petal-like condition; but it far more frequently happens that the stamens are entirely suppressed, the adventitious bud supplying their place; thus was it in the Dianthus represented in the adjoining woodcut, fig. 66, where the stamens were entirely absent, and their places supplied by flower-bearing branches. This Dianthus has the more interest from its similarity to the one described by Goethe, Metam. der Pflanzen, cap. 16, sect. 105; but in that instance median prolification also existed. For my specimens I am indebted to Mr. T. Moore.

It occasionally happens that an adventitious bud arises from the axil of a monocarpellary pistil. This takes place sometimes in LeguminosÆ, and seems to have been more frequently met with in Trifolium repens than in other plants. The species named is, as is well known, particularly subject to a reversion of the outer whorls of the flower to leaves, and even to a leaf-like condition of the pistil. There are on record instances wherein a leaf-bud has been placed in the axil of a more or less leaf-like carpel; while at other times a second imperfect carpel has been met with in the axil of the first.[140] I have myself seen numerous imperfectly developed cases of this kind.

It may be asked whether such cases are not more properly referable to central prolification—whether the axis is not in such flowers terminated by two, rather than by one carpel? It is, however, generally admitted by morphologists that the solitary carpel of LeguminosÆ is not terminal, but is the sole existing member of a whorl of carpels, all the other members of which are suppressed as a general rule, though exceptional instances of the presence of two and even of five carpels have been described.[141]

Again, the adventitious bud or carpel is placed, not laterally to the primary one, or opposite to it, on the same level, but slightly higher up—in fact, in the axil of the primary carpellary leaf. Griffith figures and describes[142] an instance of the kind in a species of Melilotus. The stalk of the ovary is mentioned as having a sheathing base, bearing in its axil a prolongation of the axis of inflorescence, in the form of a short spike with hairy bracts and imperfect flowers, the latter having a well-formed calyx and rudimentary petals and stamens. Griffith infers, from this specimen, that the legume is not to be considered as a terminal leaf.

List of Genera in which Axillary Prolification has been observed.

Complicated prolification.—From what has been before stated it may be seen that prolification of two or more kinds may coexist in the same flower. Mixed leafy and floral prolification is not unfrequent in proliferous roses, where a shoot is, as it were, prolonged through the centre of the original flower and terminated by a second flower, or even by a cluster, as is well shown in the accompanying figure (fig. 67). Median and axillary prolification, also, not unfrequently coexist in the same flower; thus, in a proliferous rose forwarded to me by Mr. W. Thomson (fig. 68), the following changes were observed:—the swollen portion below the calyx, the "hip," was entirely absent; the sepals were leaf-like in aspect, the petals unaffected; above the petals the axis was prolonged for a short distance and then bore a circlet of miniature, sessile roses, destitute, indeed, of calyx, but provided with numerous petals, stamens, and pistils. Above these lateral flowers, the prolonged axis bore a number of scales in many rows. The scales were in their turn surmounted by a whorl of five perfect leaves, beyond which, again, the axis was prolonged into a leafy shoot terminated by a flower bud, the whole constituting a remarkably complicated admixture of elements belonging to the flower, the bud, the inflorescence, and the leafshoot.[143]

Proliferous flowers of Orchids also occasionally present great complexity in the arrangement of their parts. An instance of this kind was described by myself from specimens furnished by Dr. Moore, of Glasnevin, in the 'Journal of the Linnean Society,' vol. ix, p. 349, tabs. x, xi, and from which the following summary is extracted:

The primary flowers were composed of five distinct whorls, and of at least two others less perfectly developed. These primary flowers did not give rise to median formations, but they produced secondary buds in the axils of the segments of the perianth. These latter buds were themselves the subject of tertiary prolification of both kinds, median and axillary. The tertiary median growths, like the primary flower, did not develop median buds, but only lateral ones—quaternary axillary prolification.

The accompanying diagrams are intended to show the plan of arrangement in these flowers. Fig. 69 shows the disposition of parts in the primary flower and the situation of the axillary buds. Fig. 70 shows the primary flower without any central prolongation, but giving off axillary buds, two of which are shown in the diagram, 2, 2; these are, each of them, the subject of both median, 3, 3, and axillary prolification, 4', 4'.

In Narcissus major a similar combination of both forms of prolification exists, as described by Morren.[144]

On the general subject of Prolification in flowers, in addition to the authorities already cited, the reader may refer to the following among many others:

Prolification of the embryo.—This term was applied by Moquin-Tandon to a peculiar condition of the almond (Amygdalus), in which, indeed, it is not of unfrequent occurrence. In these cases one almond encloses within its cotyledons a second embryo, and this, again, in some instances, a third, the little plants being thus packed like so many boxes one within the other. The supplementary embryos are, in the ripe state at least, quite separate and detached one from another. These cases differ from the ordinary instances wherein there is an increased number of embryos in one seed in their position. In the latter case, as often happens in the seeds of the orange, the new products are placed by the side one of another.[146]

For other cases of prolification or the adventitious formation of buds on leaves, roots, &c., see under Heterotaxy.

CHAPTER III.
HETEROTAXY.

Under this category are here included a variety of deviations from the ordinary arrangement and position of parts which cannot conveniently be classed under the preceding or under other headings. The term heterotaxy is intended to apply to the production of organs in situations where, under usual circumstances, they would not be formed. It thus does not include cases of substitution, where one part is replaced by another, or more or less metamorphosed, nor cases of multiplication, nor of prolification which are characterised not only by the production of members in unwonted situations, but also in unwonted numbers. From the very nature of the anomalies, and specially from the scanty knowledge we possess concerning their mode of development, it is not possible to allocate them in all cases correctly, and moreover many of them might as well be placed in one group as in another.

Formation of adventitious roots.—This is of exceedingly common occurrence in a vast number of plants, so much so that in most cases it cannot be considered as in any way abnormal; there are, however, a few instances where the formation of these organs may be considered to come within the scope of teratology, or, at least, where their production is the result of injury or of some unfavorable condition to which the plant is exposed.

Thus the production of adventitious roots on the stem of the vine is considered to be due to untoward circumstances impairing the proper action of the ordinary subterranean roots. So, too, the formation of roots on the upper portions of stems that are more or less decayed below, as in old willows, is to be considered as an attempt to obtain fresh supplies through a more vigorous and healthy channel.

A similar occurrence often arises as a consequence of some injury. Virgil had this circumstance in view when he wrote

I have seen many specimens of adventitious roots produced on the olive in the way just mentioned.

In the 'Gardeners' Chronicle,' January 8th, 1853, p. 21, is described a curious formation of roots in the fissure between two divisions of a laburnum stem. In the same journal, January 1st, 1853, p. 4, Mr. Booth mentions the case of a Cornish elm, the trunk of which was divided at the top into two main divisions, and from the force of the wind or from some other cause the stem was split down for several feet below the fork. Around the edges of the fracture, layers of new bark were formed, from which numerous roots issued, some measuring an inch in diameter and descending into the cleft portion of the tree: similar instances must be familiar to all observers.

It may happen that these roots sent down into the cavity of a decaying trunk may, after a time, become completely concealed within it, by the gradual formation and extension of new wood over the orifice of the cavity formed by the death and decay of the old wood. Such is presumed to be the explanation of a specimen of this kind in the possession of the writer, and taken from a cavity in an apparently solid block of rosewood; externally there were no marks to indicate the existence of a central space, but when the block was sawn up for the use of the cabinet-maker, this root-like structure was found in the centre and attached to one end of the cavity.

The production of roots which ultimately serve as props to support the branches, or as buttresses to compensate for the increasing weight of branches and foliage, is also a familiar occurrence. The huge gnaurs and burrs met with occasionally on some trees often produce great quantities, not only of adventitious buds, but of roots also.

The leaves, equally with the stems, have the power of emitting roots under certain conditions, as when the leaves are in close contact with moist soil or as the result of injury. This happens in some plants more readily than in others—Bryophyllum calycinum is a well-known instance. Mr. Berkeley has described the formation of roots from the fractured leaves of celery,[147] and also in a cabbage where a snail "having gnawed a hole into the middle of a leaf at its junction with the stem, a fascicle of roots was formed, bursting through the tissue lining the cavity, and covered with abundant delicate hairs after the fashion of ordinary radicles."

The production of adventitious roots is not limited to the ordinary leaves of the plant, but may be manifested on the cotyledons; thus Irmisch describes cases of this kind in the cotyledons of Bunium creticum and Carum Bulbocastanum.[148] I have figured and described an analogous case in the cotyledons of the Mango (fig. 72).[149]

To this formation of adventitious roots the gardener owes the power he has of propagating plants by cuttings, i.e., small portions of the stem with a bud or buds attached, or in some cases from portions of the leaves, of the roots themselves, or even of the fruit, as in the case of the cactus (Baillon). Care also has to be exercised in grafting certain fruit trees not to allow the grafted portion to be too close to the ground, else the scion throws out roots into the soil, and the object of the cultivator is defeated.

Formation of adventitious buds on roots.—One of the characteristics by which roots are distinguished from stems in a general way consists in the absence of buds; but, as is well known, they may be formed on the roots under certain circumstances, and in certain plants, e.g., Pyrus Japonica, Anemone Japonica, &c. What are termed suckers, owe their origin to buds formed in this situation.

If roots be exposed or injured, they will frequently emit buds. The well-known experiment of Duhamel, in which a willow was placed with the branches in the soil and the roots in the air, and emitted new buds from the latter and new roots from the former, depended on this production of adventitious organs of either kind.

Gardeners often avail themselves of the power that the roots have of producing buds to propagate plants by cuttings of the roots, but in many of these cases the organ "parted" or cut is really an underground stem and not a true root.

M. Claas Mulder has figured and described a case in the turnip-radish of the unusual formation of a leafy shoot from the root, apparently after injury.[150] From the figure it appears as if the lower portion of the root had been split almost to the extremity, while the upper portion seems to have a central cavity passing through it. From the angle, formed by the split segments below, proceeds a tuft of leaves, some of which appear to have traversed the central cavity and to have emerged from the summit, mingling with the other leaves in that situation. The production of a flower-bud has even been noticed on the root of a species of Impatiens.

Formation of shoots beneath the cotyledons.—The tigellar or axial portion of the embryo plant, as contrasted with the radicle proper, is very variously developed in different cases; sometimes it is a mere "collar" bearing the cotyledons, while at other times it is of considerable size. Generally it does not give origin to shoots or leaves other than the seed-leaves, but occasionally shoots may be seen projecting from it below the level of the cotyledons. This happens frequently in seedling plants of Anagallis arvensis, Euphorbia peplus, and other species, Linaria vulgaris, some UmbelliferÆ, &c.[151]

Adventitious formation of leaves.—The term phyllomania has been vaguely applied both to the production of an unwonted number of leaves and to their development in unusual situations. Under the present heading the latter class of cases are alone included. The extraordinary tendency in some Begonias to develop leaves or leafy excrescences from their surfaces is elsewhere alluded to, and is, in reality, a species of hypertrophy or over-luxuriant growth.

In some flowers where the inferior ovary is supposed to be, in part at least, formed by a dilatation of the top of the flower-stalk, leaves have been met with proceeding from the surface of the ovary or fruit, as in CratÆgus tanacetifolia, roses, pears, gooseberries, &c. In a specimen of NymphÆa alba I have met with scale-like leaves projecting from the surface of the fruit (or torus?), and which did not appear to be metamorphosed stamens or styles (fig. 76).

For other illustrations of increased leaf-formation, see Multiplication of foliar organs.

Production of leaves on a usually leafless inflorescence.—The development of the bracts of an inflorescence to such an extent that they resemble ordinary leaves is elsewhere alluded to as of common occurrence. It happens far less frequently that leaves are developed on an inflorescence usually destitute of them, without any metamorphosis or substitution, and without any formation of adventitious buds, such as happens in prolification. Such a partial change from a floriferous to a foliiferous branch may be seen in a specimen of Sambucus nigra in the Smithian herbarium in the Linnean Society, where the ultimate branches of the cyme bear small leaves. My attention was directed to this specimen by the Rev. W. Newbould.

Jacquin figures an analogous case in Sempervivum sediforme,[152] in which the branches of the inflorescence were prolonged into leafy shoots.

Sometimes from the side of a flower-stalk or scape, which usually does not bear leaves, those organs are produced. The common dandelion, Taraxacum, sometimes offers an illustration of this, and also the daisy (Bellis).[153] In a specimen of fasciated cowslip given me by Mr. Edgeworth there was a similar formation of leaves on the flattened stalk.

Production of leaves or scales in place of flower-buds.—The position of the leaf and of the flower-buds respectively is, in most plants, well defined, but occasionally it happens that the former is formed where, under ordinary circumstances, the latter organ should be. This may happen without the formation of any transitional organs between the two, and without actual increase in the number of the buds. Where there is evidently a passage from leaf-bud to flower-bud, or vice versÂ, the case would be one of metamorphy. If the number of buds be augmented, or they be mixed with the flower-buds, then it would be referable to leafy prolification of the inflorescence. There remains a class of cases wherein there is a complete substitution of one structure for the other, it may be without the slightest indication of transition between the two, and without any admixture of leaf-buds among flower-buds, or any absolute increase in the number of organs, as in Prolification. Such a case is represented in fig. 78, which shows a portion of the stem of a species of Valeriana, bearing at the summit, not an inflorescence, but a tuft of leaves without the slightest indication of flowers.

Drs. Hooker and Thomson relate that in Northern India the flowers of Anemone rivularis are very generally absent, and their place supplied by tufts or umbels of leaves.[154] In the collection of the late Mr. N. B. Ward was a specimen of lupin in which the flowers were all absent, and their place supplied by tufts of leaves.

A similar appearance has been noticed in CompositÆ, and I owe to the kindness of Professor Oliver the communication of a specimen of a species of Bidens from Peru, in which the capitula, instead of consisting of florets, as usual, contained tufts of linear ciliolated bracts within the involucre, without a trace of flowers. In the eleventh volume of the 'LinnÆa,' 1837, p. 301, Von Cesati figures and describes an analogous case in Carduus crispus. The same author[1] records a similar instance in the umbel of Seseli coloratum, where the place of the flowers was occupied by stalked tufts of leaves. In the 'Gardeners' Chronicle,' October 6th, 1860, p. 894, is mentioned an instance where the blossoms of the pea were entirely absent, and their place supplied by accumulations of small, ovate, green scales, thus presenting an appearance similar to that brought about by the inordinate multiplication of the sepals in the "wheat-ear carnation," and in the Sweet William, and not unlike the condition met with in Bryophyllum proliferum. In Digitalis purpurea a similar anomaly is sometimes met with.

In the apple I have observed leafy shoots bearing terminal tufts of leaves where the flower should have been, so that what, under ordinary circumstances would be a corymb of flowers, is here represented by a series of tufts of leaves. In the cultivated azaleas also, leafy shoots occupying the position of the flower may occasionally be met with.

In Bouchea hyderabadensis I have seen the inflorescence more than usually branched and covered with little tufts of bracts, without a trace of true flower. A similar condition seems not infrequent in Gentiana Amarella, as I have not only met with the plant myself in this condition, but have been favoured with specimens by Mr. Pamplin, Mr. Darwin, and others. In Phyteuma spicatum an analogous appearance has been recorded.

Among Griffith's collections from Affghanistan is a species of willow (Salix) in which the inflorescence replaced by a much branched panicle, bearing a quantity of minute bracts, in the axils of which nestle numerous small buds. In another specimen the inflorescence preserves its usual catkin-like shape, but the flowers are replaced by little tufts of leaves. M. Germain de Saint Pierre mentions a case wherein the flowers of Alisma parnassifolia were completely replaced by leaf-buds.[155]

Here, also, may be mentioned the curious aggregations of scales which occur in some grasses, in RestiaceÆ, JuncaceÆ, and other orders, in which the inflorescence is made up of collections of scales or bracts with no trace of floral structure. Fig. 79 shows this in a species of Willdenovia, and a very good example is figured in a bamboo, Pseudostachyum polymorphum, by General Munro.[156]

"Rose willows" (fig. 80) owe their peculiar appearance to a similar cause, the scales of the catkin being here replaced by closely crowded leaves. These aggregations of scales or leaves are not confined to the inflorescence, but may be found in other parts of the plant, and may be frequently met with in the willow, birch, oak, &c., generally as the result of insect puncture. On the other hand, the production of leaves or leaf-buds in place of flowers is, as is well known, generally the consequence of an excess of nutrition, and of the continuance rather than of the arrest of vegetative development.[157] It has even been asserted that a flower-bud may be transformed into a leaf-bud by removing the pistil at a very early stage of development, but this statement requires further confirmation.[158]

Viviparous plants.—The spikelets of certain grasses are frequently found with some of their constituent parts completely replaced by leaves, like those of the stem, while the true flowers are usually entirely absent. A shoot, in fact, is formed in place of a series of flowers. In these cases it generally happens that the outermost glumes are changed, sometimes, however, even the outer and inner paleÆ are wholly unchanged, while there is no trace of squamulÆ or of stamens and pistils within them, but in their place is a small shoot with miniature leaves arranged in the ordinary manner.

The grasses most commonly affected in this manner are Dactylis glomerata!, Poa bulbosa!, Poa annua!, P. trivialis!, pratensis!, alpina!, angustifolia, and laxa, Cynosurus cristatus, Festuca nemoralis, F. ovina!, Glyceria fluitans!, Gl. aquatica, Aira alpina!, cÆspitosa!, Phleum phalaroides, Lolium perenne!, Alopecurus pratensis!, Agrostis alba, Holcus mollis!

From an examination of the structure of viviparous grasses Von Mohl was led to the conclusion that the lower palea is to be considered as a bract, and not a perianthial leaf, because the base of the palea surrounds the stem or axis of the spikelet entirely, and both its margins cohere towards its lower extremity.[159]

A similar condition occurs not infrequently in Polygonum viviparum, and in JuncaceÆ, CyperaceÆ, &c.

In the genus Allium an analogous formation of little buds or bulbils takes place in lieu of flowers; this is specially the case with A. vineale, the flowers of which are rarely seen.

Other illustrations of a similar character, where the adventitious leaf-buds are mixed in amongst the flower-buds, are cited under the head of Prolification of the Inflorescence.

Formation of buds on leaves.—The formation of little bulbs upon the surfaces or edges of leaves, forming what are called viviparous leaves, has long been familiar to botanists amongst Alliums. Professor Alexander Braun,[160] who has paid much attention to this subject, divides cases of this kind according to the position of the buds; thus, for instance, they are sometimes formed upon the upper portion of the leaf or petiole, as in many ferns, in NymphÆa guineensis, some Arads, &c. The same condition has been met with as a teratological occurrence in the leaves of Cardamine pratensis, Hyacinthus Pouzolzii, Drosera intermedia,[161] Arabis pumila, Chelidonium majus, Chirita sinensis,[162] Episcia bicolor,[163] Zamia, &c.[164] Many species of Begonia possess the power of emitting buds from the petioles and veins of the leaf; the little ramenta or scales which so plentifully beset the surface of some of these plants likewise, in some instances, pass gradually into leaves. B. phyllomaniaca, Mart., is the species best known as manifesting this tendency, but others have it also.[165]

Buds are also very often formed upon the margins of the leaf, the best known instance of which occurs in Bryophyllum calycinum; Weinmann[166] figures an instance of this kind in Alchemilla minima, or they may occur upon the lower surface of the leaf, as in Ornithogalum scilloides and longe-bracteatum. M. Duchartre[167] mentions a case in the tomato in which the leaves gave origin to small leaf-bearing branches, which, of course, must have originated from buds, just in the same way as in the Drosera before mentioned.

Formation of buds in the pith.—This is said to be a normal condition in the curious Stangeria paradoxa,[168] and Mr. Berkeley records an instance of this in sea-kale[169] (fig. 83) where the crown had been injured, and buds were seen sprouting from its centre.

It will be remarked that the adventitious production of buds, like that of roots, is very often consequent on decay or injury. The Dutch bulb-growers have availed themselves of this latter circumstance in the propagation of hyacinths. Mr. Fortune, who published some articles on this subject in the 'Gardener's Chronicle,'[170] describes two special modes as adopted by these skilful horticulturists—the one to make two or three deep cuts at the base of the bulb, destroying the nascent flower-stalk when, after a time, small bulbs are formed along the edges of the cut surfaces (figs. 84, 85). The other method is effected by scooping out the interior of the base of the bulb, thus leaving exposed the cut ends of the sheathing leaves arranged concentrically; along these lines the new bulbs are, after some time, formed in great numbers (fig. 86).

Production of gemmÆ in place of spores.—An instance of this is recorded by Dr. Montagne[171] in the case of a moss, Encamptodon perichÆtialis, in which, in the interior of the capsule, in lieu of spores numerous minute gemmÆ of the same nature as those in the cup of Marchantia were seen.

Formation of flowers on leaves.—It is very doubtful whether a flower-bud has ever been found actually on a leaf. Mere adhesion of the pedicels of the leaf, such as happens in Ruscus, in Helwingia, Erythrochiton hypophyllanthus, and a few other plants, is, of course, not really to be considered in the light of an actual growth from the leaf, and it is very doubtful in the present state of our knowledge whether the case of the Nepaul barley should find a place here, but for convenience sake it is placed in this section, as it is uncertain at present where it properly belongs.

This curious plant has been described and figured by Irmisch in the 13th volume of the 'LinnÆa,' p. 124, t. iv; also by Professor Henslow, 'Hooker's Journal of Botany,' 1849, vol. i, p. 33, tabs. 2, 3. The lower palea of this plant forms an inverted flower-bud upon its midrib. In some fresh specimens which I have lately examined I find the structure to be as follows:—On each notch of the rachis there are three spikelets (fig. 88), each one-flowered, and each provided with two linear glumes; the outer palea in all cases is three-lobed at the summit, the central lobe being oblong and hollow, forming a kind of hood (figs. 87–89), and covered with hairs, which are directed downwards towards the centre of the plant. The two lateral lobes are more pointed than the central one; like it they are provided with hairs, but the hairs, in this case, are turned away from the centre of the plant. The cavity of the side lobes is generally empty, but that of the central lobe is occupied by a very slender stalk, which is apparently the termination of the midrib, but which is bent inwards at an acute angle, so as to occupy the hollow space (figs. 90–91). On this slender axis are developed two florets, more or less imperfect in their structure. Only one of the florets that I have seen contained a perfect ovary. The tips of the lateral lobes of the paleÆ in the primary flower are sometimes extended into a long awn. A similar awn may also be occasionally found on the tips of the paleÆ of the rudimentary florets. The occurrence of an adventitious axial structure with rudimentary flowers has been adduced in support of the opinion that the lower paleÆ is, at least so far as its midrib is concerned, an axial rather than a foliar structure, but in the present uncertain state of our knowledge as to the morphology of grasses it is hazardous to risk any explanation founded on so exceptional a case as that of the Nepaul barley.[172]

Production of flower-buds in place of leaf-buds.—Under natural circumstances this does not appear to be of so common occurrence as the change above alluded to, but by the art of the gardener the change is often effected. In rhododendrons and in peach trees and roses I have met with this change occurring without human agency. The means adopted by the gardener are such as check the luxuriance of the leaf-shoots,[173] and this is effected in various ways, as by continuous "pinching" or removal of the leaf-buds, by pruning, ringing the bark, confining the roots, limiting the supply of nutriment, and other means all based on the same principle. Some of the Cape bulbs (Cyrtanthus) are known not to produce their flowers till their leaves have received, in some manner, a check. Fires which often destroy the herbage thus have the effect of throwing the plant into bloom. A very remarkable instance is recorded of the production of flower-buds after an injury to the leaf-buds in the 'Bulletin of the Botanical Society of France,' vol. ix, p. 146. It appears that during the war of the French against the Arabs in Algiers, the latter planted several hundreds of Agaves with a view to obstruct the passage of the French cavalry. The soldiers hacked these plants with their sabres, and cut out the central tuft of leaves, or the heart, as gardeners call it. The following season almost every one of these Agaves sent up their large handsome flower-spikes. It is well known that, under ordinary circumstances, these plants do not flower except at long intervals of time.

Presence of flowers on spines.—That the spine, as a contracted branch, should occasionally produce flowers is not to be wondered at, though the occurrence is by no means common. M. Baillon showed at a meeting of the Botanical Society of France ('Bulletin,' vol. v, 1858, p. 316) a branched spine of Gleditschia bearing a flower at the end of each of the sub divisions. This was, therefore, strictly analogous with those cases in which the peduncle is normally spiney.

Formation of flower-bud on the petals.—An instance of this, it is believed, the only one on record, is cited in the 'Gardeners' Chronicle' for 1865, p. 760, by the Rev. M. J. Berkeley, who describes the formation of a flower-bud on the surface of a petal of Clarkia elegans. Reasoning from analogy there seems no reason why buds should not be formed on the petals as well as on the leaves.

Formation of buds on fruits.—This is a point of some moment with reference to the share which the axis takes in the production of "inferior" fruits. A very frequent malformation in pears is one wherein a second pear proceeds from the centre of the first, and even a third from the centre of the second.[174] Pears are occasionally also observed arising either from the axils of the sepals of the primary pear or from the axil of leaves originating on the outer surface of the fruits—using the term fruit in its popular sense. These cases afford strong confirmation of the view that the outer portion of the so-called fruit in these plants is rather to be considered as an expansion and hollowing-out of the flower-stalk, than as formed from the calyx-tube. It is noteworthy that the true carpels and seeds are frequently entirely absent in these cases.[175] Further reference to these fruits will be made under the head of Hypertrophy.

M. TrÉcul has described and figured an instance in a species of Prismatocarpus, in which a second flower proceeded from the axil of a bract attached to the side of the fruit of the first flower.[176] A similar growth was observed in the fruit of Philadelphus speciosus by M. A. Gris, who observed that the so-called calyx-tube was provided with two small bracts, from the axil of one of which proceeded a small flower-bud.[177]

The fruits of Opuntia Salmiana, O. fragilis,[178] O. monacantha, and of some species of Echinocactus, have been observed to form small fruit-like branches around their summits. M. NapolÉon Doumet describes the fruit as ripening as usual, but as being destitute of seeds in the interior; after a little while the fruit begins to wither, and then a circle of small buds, like those of the stem, may be seen at the top of the fruit, each bud springing from the axil of a little tuft of wool and spines found on the fruit. These little buds elongate into long shoots, produce flowers the following year, which flowers exhibit the same peculiarity. Gasparini and Tenore are said to have recorded the same fact as long since as 1832. The specimen from which the figure (fig. 93) was taken produced its fruits in the Royal Gardens at Kew, and is now preserved in the museum of that establishment. The adventitious growth in these cases appears to arise from the tufts of spines, which, it has been suggested, are the homologues of the sepals. There can, however, be little doubt that the outer and lower portion of the fruit of Opuntia and its allies is a dilatation of the flower-stalk. This is borne out by the fruits of Pereskia, which bear leaves on their surface arranged spirally; indeed, the fruits of Pereskia Bleo are mentioned as producing buds from their summits, in the same way as the Opuntia just cited. P. Bleo is said, by M. Delavaud,[179] to present this anomaly as a constant occurrence. On the summit of the primary fruit, arising apparently from the axils of the sepals, or of small leafy bracts in that situation, are a series of fruit-like branches, which, in their turn, are surmounted by others, even to the fourth generation.

The fruits of Tetragonia expansa frequently have attached to their side a secondary flower or fruit in such a position as to lead to the inference that it springs from the upper portion of the peduncle which is dilated to invest the true carpels. In other instances it is due to an adhesion of the pedicel to the side of the fruit. In either case the production of an adventitious bud might be considered as an illustration of prolification of the inflorescence, though not as was supposed by Moquin and others of axillary prolification.[180]

Buds have also been produced artificially on the surface of some of the fruits in the construction of which the axis is supposed to share; thus, the unripe fruits of some species of Lecythis were stated by Von Martius, at a meeting of the German Naturalists at Carlsruhe, to produce buds when placed in the earth. The fruit of these plants is probably of the same nature as that of the PomaceÆ, and Baillon[181] succeeded in producing buds on the surface of the inferior ovary of JussiÆa.

Some of the cases just mentioned have been considered to be instances of prolification of the fruit, but the fruit has little to do with the appearances in question.

Formation of adventitious flowers and fruits within the ovary.—This generally arises either from substitution of a flower-bud for an ovule or from prolification; there are certain cases, however, where the new growth seems not to be either due to metamorphosis or to prolification strictly.

The cut, fig. 94, represents a case where, in the dilated upper portion of the ovary of Sinapis arvensis, two flower-buds were found projecting from a raised central line, corresponding, as it would seem, to the midrib, and not to the margins of the carpel. Similar cases have occurred in Nasturtium amphibium, Brassica Rapa, and Passiflora quadrangularis.

In Bromfield's 'Flora Vectensis,' p. 35, the following account is given of an abnormal development in Cardamine pratensis: "On the lower part of the corymb were several seed vessels on pedicels changed from their usual linear to an ovate elliptical figure, so as to resemble a silicula. These, on being opened, were found to contain petals of the usual colour, which in the pods above had burst from their confinement and appeared as semi-double flowers; the valves of the pod answering to the true calyx. * * * From their verticillate arrangement it is evident that these petaloid expansions were not transformed seeds, but simply a development of the common axis within the ovary into an abortive whorl of floral organs, besides which there were evident rudiments both of stamens and germens in the centre of the bundle." Baillon[182] also records a case of the same nature in Sinapis arvensis.

Formation of stamens within the cavity of the ovary.—The only instance of this that has come under the author's observation occurred in some flowers of BÆckea diosmÆfolia, Rudge, for an examination of which he is indebted to Mr. Bentham.

In the normal flower there is a turbinate hollow calyx, whose limb is divided into five serrated lobes; alternating with these latter, and springing from the throat of the calyx, are the petals. Originating from the same annular disk as the petals are the stamens, seven or eight in number. The ovary is partially adherent, is surmounted by a style, and has two or three loculi with an axile placenta, to which several small curved ovules are attached. The malformed flowers did not present anything peculiar in their outer parts, nor did the ovary, partially immersed within the expanded top of the flower-stalk and the calyx-tube, which is continuous with that organ, show externally any indication of the change within. On cutting it across, however, in any direction, numerous perfect stamens (filaments and anthers) were seen projecting from the walls of the cavity (fig. 98). In most of the flowers the ovary was one-celled; but in a few there was the usual axile placenta; yet even in these latter cases the stamens originated from the walls of the cavity, and not from the placenta. The stamens presented different degrees of development; in some cases they were fully formed, the anther-lobes open, and the pollen exposed; while in other instances the filaments were involute or circinate, just as the ordinary stamens are in the unexpanded flower-bud. In some cases imperfect stamens were found, mere barren filaments, with or without rudimentary anthers at the top. In no instance was there a perfect ovule, or, indeed, any trace of ovules. The stamens appeared to be arranged irregularly on the walls of the ovarian cavity; and while they were certainly more numerous at the lower portion (that now generally considered to be formed by the cup-like end of the pedicel), they were not wanting in the upper half of the ovary (or that which is probably formed from the carpellary leaves).

Fig. 98.—1. Vertical section of flower of BÆckea diosmÆfolia, showing stamens within the ovary; magnified ten times. 2. Transverse section of ovary. 3. Stamen. 4. Imperfect stamen.

This case differs from most that have been recorded, and in which there has been a more or less complete substitution of anther for carpel, or where the tissues of the carpel have produced pollen, and so taken upon themselves the appearance and functions of anthers. Instances of this latter kind are not uncommon; but in the BÆckea there were perfect stamens proceeding from perfect and completely closed ovaries. Moquin-Tandon[183] cites from Agardh an instance which seems more closely to resemble the state of things in the BÆckea, and which occurred in a double hyacinth, wherein both anthers and ovules were borne on the same placenta. Probably, though the fact is not stated, the ovary of the hyacinth was open; and we are told that the flower was double—that it was, in fact, modified and changed in more organs than one; while in the BÆckea nothing at all unusual was observed till the ovary was cut open. The style was present even in those flowers where there was no axile placenta; hence in these cases it could not be, as Lindley stated it to be in the closely allied Babingtonia, a prolongation of the placenta.[184]

Formation of pollen within the ovules.—This has now been recorded in two instances by Mr. S. J. A. Salter in Passiflora cÆrulea and in P. palmata,[185] and by the author in Rosa arvensis.[186]

In the case of the passion-flower there were various malformations in the ovaries, which were all more or less split open at the distal end, indicating a tendency towards dialysis. The pollen-bearing ovules were borne on the edges of these ovaries, and presented various intermediate conditions between anthers and ovules, commencing at the distal extremity of the carpel with a bi-lobed anther, and passing in series to the base of the ovary, an antheroid body of ovule-like form, a modified ovule containing pollen, an ovule departing from a perfectly natural condition only in the development of a few grains of pollen in its nucleus, and, finally, a perfect, normal ovule.

In the flowers of the Rose the stamens exhibited almost every conceivable gradation between their ordinary form and that of the carpels, while some of the ovules contained pollen in greater or less abundance. Speaking generally, the most common state of things in these flowers was the occurrence on the throat of the calyx, in the position ordinarily occupied by the stamens, and sometimes mingled with those organs, of twisted, ribbon-like filaments, which bore about the centre one or more pendulous, anatropous ovules on their margins. Immediately above the latter organs were the anther-lobes, more or less perfectly developed, and surmounting these a long style, terminating in a fringed, funnel-shaped stigma. Sometimes the ovules were perfect, at other times the nucleus protruded through the foramen, while in a third set the nucleus was included within the tegument, the ovules having in all respects their natural external conformation, containing, however, not only pollen-grains, but also a layer of those peculiar spheroidal cells, including a fibrous deposit, which are among the normal constituents of the anther. In one case, where the coat of the ovule was imperfect, and allowed the nucleus to protrude, the pollen was evidently contained within the central mass of the structure. In this instance the fibrous cells were not detected, these being only found in cases where the investment of the ovule was perfect; and hence it seems likely that the fibrous cells were part of the coat of the ovule, while the pollen was formed within the nucleus. In no case was any trace of embryo sac to be seen.

The main interest, as Mr. Salter remarks, in these cases is physiological; so far as structure alone is concerned, there does not appear any reason why pollen-grains should not be developed in any portion of the plant; the mother cells in which the pollen is formed not differing, to all outward appearance, from any other cells, unless it be in size.

The fundamental unity of construction in all the organs of plants could hardly be better illustrated than by these cases; while, in spite of their exceptional nature, they must be of great interest physiologically, as showing the wide limits of possible variation which thus may even involve the sex, "for an ovule to develop pollen within its interior," says Mr. Salter, "is equivalent to an ovum in an animal being converted into a capsule of spermatozoa. It is a conversion of germ into sperm, the most complete violation of individuality and unity of sex. * * * * The occurrence of an antheroid ovule and a normal ovule on the same carpellary leaf realises the simplest and the most absolute form of hermaphroditism."

It must, however, be remarked that the term substitution would be preferable to conversion. There is, at present, no evidence to show that the germinal vesicles were present in these cases; on the other hand, it seems most probable that they were not, so that the presence of the pollen-cells must be considered as simply adventitious. It can hardly be that they were, in the first instance, germinal vesicles, which, in course of time, became so modified as to assume the appearance of pollen-grains. Between the nucleus of the ovule and the tubercle of cellular tissue constituting the primordial anther, there is little or no difference, so that it may be said that, for a time, there is no distinction of sex in the nascent flower, but as development goes on, the difference becomes perceptible. It cannot at present be stated what precise circumstances induce the one mass to form mother-cells and pollen-grains, and the other to develop an embryo sac and germinal vesicles. Position and external circumstances may have some indirect effect, and it may, perhaps, be significant that in all the instances of polliniferous ovules, the ovular structures have been exposed on an open carpel or otherwise, in place of being confined within the cavity of a closed ovary, as under ordinary circumstances. Even among Conifers the ovuligerous scales are so closely packed that there is little or no exposure of the ovules. But, apart from all speculative notions as to the relation between the structure and functions of the anther and of the ovule respectively, and of the possibility or the reverse of parthenogenesis, it will clearly be necessary in any future alleged occurrence of the latter phenomenon to ascertain whether any or all of the apparent ovules are, or are not, anthers in disguise.

Homomorphic flowers of "CompositÆ."—In a large section of the CompositÆ there is, as is well known, a distinction between the florets of the "disc" and those of the "ray," the latter being ligulate, the former tubular.

In what are erroneously called double flowers in this order, e.g. in the Chrysanthemum, Dahlia, &c. &c., the florets are all ligulate. This change is sometimes classed with peloria, but there is no abnormal regularity in these cases. On the other hand, were the ligulate florets to be all replaced by tubular ones, the term peloria would be more strictly applicable. It will be remembered that in the sub-order LiguliflorÆ, the florets are naturally all ligulate, so that the change above mentioned is not in itself a very grave one.

Heterotaxy affecting the inflorescence.—Under the head of Prolification, Heterogamy, &c., various deviations from the normal inflorescence are alluded to. In this place, therefore, it is only necessary to mention certain rare deviations from the customary arrangement of the inflorescence, such as the change from a definite centrifugal form of inflorescence to an indefinite centripetal one. This occurs occasionally in roses, where the shoot, instead of terminating in a flower-bud, lengthens and bears the flower-bud on its sides as in a raceme.

In the hyacinth, the inflorescence of which is properly indefinite, the terminal flower may frequently be found to expand first, though in order of development it may have been the last formed.

It occasionally happens that certain plants will, contrary to their usual custom, bloom twice in the same season; this usually arises from the premature development of buds which, under ordinary circumstances, would not unfold till the following spring. In these instances of what the French term "fleuraison anticipÉe," the position of inflorescence is not changed, but there are other cases where the position of the inflorescence is altered, as in the laburnum, where, in some seasons, racemes may be seen springing from short lateral "spurs" along the sides of the branches, as well as from the extremities of long shoots.

Of a similar nature are those cases wherein stems or branches usually sterile become fertile; this happens in EquisetaceÆ,[187] in RestiaceÆ, and other orders. In the equisetums, the condition in question has been specially noticed to occur after prolonged drought.

EquisetaceÆ are likewise subject to an anomaly called by Duval Jouve interruption of the spike, and wherein the scales bearing the spore cases are separated by whorls of branches instead of forming one compact unbroken spike as usual.

This alternation of the organs of vegetation and reproduction may also be seen occasionally in Typha, and other plants.

Kirschleger describes a case in which the male catkins of Salix cinerea were placed at the ends of the branches instead of being lateral productions; moreover the usual articulation was not formed, so that the catkin was persistent instead of deciduous.[188]

Supra-soriferous ferns.—In the great majority of ferns the sori or clusters of spore cases are placed on the under surface of the fronds; nevertheless, a few cases are on record where the fructification is produced on the upper as well as on the lower surface, and sometimes abundantly so. This occasionally happens from the elongation of the normally placed sorus, which thus extends to the margin, and returns on the upper side, when the sori chance to be placed opposite to the marginal crenatures. But it is also frequently the case that the sori are produced on the upper side, distinctly within the margin, and where there are no corresponding sori beneath. Those varieties which have the margin crenated or lobed seem most liable to assume this abnormal supra-soriferous condition. Among the ferns in which this condition has been observed are the following: Scolopendrium vulgare, Polypodium anomalum, Hook., Asplenium Trichomanes, Cionidium Moorei.[189]

CHAPTER IV.
HETEROGAMY.

This term is here intended to apply to all those cases in which the arrangement of the sexual organs is different from what it is habitually. It is evident that in many instances there is no malformation, no monstrosity, but rather a restoration of organs habitually suppressed, a tendency towards structural completeness rather than the reverse. It must be also understood that the following remarks apply to structural points only, and are not intended to include the question of function. The occurrence of heteromorphic unions renders it necessary to keep in mind that plants hermaphrodite as to structure are by no means necessarily so as to function.

The simplest case of this alteration in the relative position of the sexes is that which occurs in monoecious plants, where the male and female flowers have a definite position, but which in exceptional instances is altered.

Change in the relative position of male and female flowers may thus occur in any monoecious plant. Cultivated maize, Zea Mays, frequently exhibits alterations of this kind; under ordinary circumstances, the male inflorescence is a compound spike, occupying the extremity of the stem, while the female flowers are borne in simple spikes at a lower level, but specimens may now and then be found where the sexes are mixed in the same inflorescence; the upper branching panicle usually containing male flowers only, under these circumstances, bears female flowers also.[190] In like manner, but less frequently, the female inflorescence occasionally produces male flowers as well.

Among the species of Carex it is a common thing for the terminal spike to consist of male flowers at the top, and female flowers at the base; the converse of this, where the female flowers are at the summit of the spike, is much more uncommon. An illustration of this occurrence is given in the figure (fig. 100). Among the ConiferÆ numerous instances have been recorded of the presence of male and female flowers on the same spike, thus Mr. now Professor Alexander Dickson exhibited at the Botanical Society of Edinburgh in July, 1860, some malformed cones of Abies excelsa, in which the inferior part of the axis was covered with stamens, whilst the terminal portion produced bracts and scales like an ordinary female cone. The stamens of the lower division were serially continuous with the bracts above. Some of the lower scales of the female portion were in the axils of the uppermost stamens, which last were somewhat modified, the anther cells being diminished, whilst the scale-like crest had become more elongated and pointed, in fact, more or less resembling the ordinary bracts.[191] Mohl, Schleiden, and A. Braun have observed similar cones in Pinus alba, and Cramer figures and describes androgynous cones in Larix microcarpa. C. A. Meyer ('Bull. Phys. Math.,' t. x, 1850) also describes some catkins of Alnus fruticosa which bore male flowers at the top, and female flowers at the base.

Change from the monoecious to the dioecious condition.—This is of less frequent occurrence than might have been anticipated. In the 'Gardeners' Chronicle,' 1847, pp. 541 and 558, several instances are noted of walnut trees bearing female flowers to the exclusion of males. The mulberry tree has also been noticed to produce female blossoms only, while in other plants male flowers only are developed.

It seems probable that the age of the plant may have something to do with this production of flowers of one sex to the exclusion of the other.

Change from the dioecious to the monoecious condition.—Androgynism.—This is of far more common occurrence than the preceding.

In the hop (Humulus Lupulus), when monoecious, the female catkins are usually borne on the ends of the branches as shown in the cut (fig. 101), and a similar thing has been noticed in Urtica dioica by Clos, 'Bull. Soc. Bot. France,' vol. 9, p. 7.

Baillon ('Etudes du groupe des EuphorbiacÉes,' p. 205) mentions the following species of that order as having been seen by him with monoecious inflorescence: Schismatopera distichophylla, Mozinna peltata, Hermesia castaneifolia. Oliver mentions ('Hook. Icon. Plant.,' t. 1044) that in Leitneria floridana the upper scales of the male catkin occasionally subtend an ovary.

It would seem that external conditions have some effect in determining the formation of one sex, as in some species of Carex, while in the case of Salix repens, Hampe[192] says that when grown partially or for a time under water, those twigs which are thrust up above the surface bear female flowers, while those twigs that blossom after the water is dried up, produce male flowers only.

CarriÈre[193] says that a plant of Stauntonia latifolia which for some years produced stamens only, now produces flowers of both sexes; it was dioecious, but is now monoecious. The same author alludes to a similar occurrence in Juniperus Virginiana. The hops is also said to vary in sexual characteristics from time to time.[194] In addition to the genera, already named, in which this production of flowers of both sexes has been observed may be mentioned Taxus! Gunnera! Urtica! Mercurialis! Restio! Cannabis! Salix! Humulus! as well as others in which the change is less frequent.

Among cryptogams a similar change occurs. As an illustration may be cited Leucobryum giganteum, as quoted from MÜller in Henfrey's 'Botanical Gazette,' i, p. 100.

Change from hermaphroditism to unisexuality.—Many flowers ordinarily hermaphrodite as to structure, become unisexual by the abortion or suppression of their stamens, or of their carpels, as the case may be. This phenomenon is lessened in interest since the demonstration of the fact by Darwin and others, that many plants, structurally hermaphrodite, require for the full and perfect performance of their functions the cooperation of the stamens and pistils, belonging to different individuals of the same species.

Some of the RanunculaceÆ constantly exhibit a tendency towards the dioecious condition, and the rarity with which perfect seeds of Ranunculus Ficaria are formed is to be attributed, in great measure, to the deficiency of pollen in the anthers of these flowers. Ranunculus auricomus also is frequently sterile. Specimens of Ranunculus bulbosus may be met with in which every flower is furnished with carpels, most of which have evidently been fertilised, although there are no perfect stamens in the flowers.

Knight and other vegetable physiologists have been of opinion that a high temperature favours the production of stamens, while a lower degree of heat is considered more favorable to the production of pistils, and in this way the occurrence of "blind" strawberries has been accounted for. Mr. R. Thompson, writing on this subject, speaks of a plantation of Hautbois strawberries which in one season were wholly sterile, and accounts for the circumstance as follows: the plants were taken from the bearing beds the year previous, and were planted in a rich well-manured border, in which they started rapidly into too great luxuriance, the growth being to leaves rather than to fruit. The following season these same plants bore a most abundant crop, hence these plants were accidentally prevented from perfecting their female organs.[195]

Mr. Darwin[196] cites from various sources the following details relating to strawberries which it may be useful to insert in this place, as throwing some light upon the production of unisexual flowers. "Several English varieties, which in this country are free from any such tendency, when cultivated in rich soils under the climate of North America commonly produce plants with separate sexes. Thus, a whole acre of Keen's seedlings in the United States has been observed to be almost sterile in the absence of male flowers; but the more general rule is, that the male plants over-run the females.... The most successful cultivators in Ohio plant, for every seven rows of pistillate flowers, one row of hermaphrodites, which afford pollen for both kinds; but the hermaphrodites, owing to their expenditure in the production of pollen, bear less fruit than the female plants."

Stratiotes aloides has been said to produce its carpels with greater abundance towards the northern limits of its geographical distribution, and its stamens, on the other hand, are stated to be more frequently developed in more southern districts.

Honckenya peploides affords another illustration of the sexual arrangements in the flower being altered as it would seem by climatal conditions. Thus, in the United States, according to Professor Asa Gray, the flowers are frequently hermaphrodite, while in this country they are usually sub-dioecious.[197]

Treviranus[198] says that the flowers of Hippuris and Callitriche are apt to be hermaphrodite in summer, but female only at a later period.

For further remarks on this subject, see sections relating to suppression of stamens and pistils.

Change from unisexuality to hermaphroditism.—This occurrence depends on one of two causes, either organs are developed (stamens or pistils as the case may be), which are habitually absent in the particular flower; or some of the stamens may be more or less completely converted into or replaced by pistils, or vice versÂ.

The first condition is the opposite of suppression; it is, as it were, a restoration of symmetry, and might be included under the head of regular peloria, inasmuch as certain organs which habitually undergo suppression at a certain stage in their development, by exception, go on growing, and produce a perfect, instead of an imperfect flower. In teratological records it is not always stated clearly to which of the two above-named causes the unusual hermaphroditism belongs, though it is generally easy to ascertain this point. Very many, perhaps all, diclinous flowers may, under certain conditions, become perfect, at least structurally. I have myself seen hermaphrodite flowers in Cucurbita,[199] Mercurialis, Cannabis, Zea Mays, and Aucuba japonica, as well as in many RestiaceÆ, notably Cannamois virgata and Lepyrodia hermaphrodita. Spinacia oleracea, Rhodiola rosea, Cachrys taurica, and Empetrum nigrum are also occasionally hermaphrodite.

Gubler[200] alludes to a similar occurrence in Pistacia Lentiscus, wherein, however, he adds that there was a deficiency of pollen in the flowers.

Schnizlein[201] observed hermaphrodite flowers in the beech, Fagus sylvatica, the ovaries being smaller than usual, and the stamens epigynous.

Baillon[202] enumerates the following EuphorbiaceÆ as having exceptionally produced hermaphrodite flowers, Crozophora tinctoria, Suregada sp., Phyllanthus longifolius, Breynia sp., Philyra brasiliensis, Ricinus communis, Conceveiba macrophylla, Cluytia semperflorens, Wall, non Roxb. Mercurialis annua and Cleistanthus polystachyus.

In some of these cases the hermaphroditism is due to the development of anthers on the usually barren staminodes, though, in other cases, the stamens would seem to be separate, independent formations, as they do not occupy the same relative position that the ordinary stamens would do if developed.[203]

Robert Brown[204] observed stamens within the utricle of Carex acuta, and Gay is stated by Moquin ('El. Ter. Veg.,' p. 343) to have observed a similar occurrence in Carex glauca.

Paasch[205] observed a similar occurrence in C. cÆspitosa, and Schauer, in C. paludosa,[206] though in the latter instance the case seems to have been one of transformation or substitution rather than one of hermaphroditism.

The second cause of this pseudo-hermaphroditism is due either to the more or less perfect mutation of male and female organs, or it may be to the complete absence of one and its replacement by another, as when out of many stamens, one or more are deficient, and their places occupied by carpels. This happens very frequently in willows and poplars, and has been seen in the beech.[207]

In Begonia frigida[208] the anomaly is increased by the position of the ovaries above, the perianth, a position due, not to any solution or detachment of the latter from the former, but simply to the presence of ovaries where, under ordinary circumstances, stamens only are formed, as happened also in a garden variety of a Fuchsia, wherein, however, the change was less perfect than in the Begonia, and in which, as the flower is naturally hermaphrodite, the alteration is of the less importance.

In hermaphrodite flowers of Carica Papaya (fig. 103) there is a single row of five stamens instead of two rows of five each as in the normal male flowers, the position of the second or inner row of stamens being occupied by five carpels, which, however, are not adherent to the corolla as the stamens are, thus, supposing the arrangement of parts in the normal male flowers to be as follows:

That of the hermaphrodite blossoms would be, in brief, as follows:

One of the most curious cases of this kind recorded is one mentioned by Mr. Berkeley,[209] wherein a large white-seeded gourd presented a majority of flowers in which the pollen was replaced by ovules. It would seem probable from the appearances presented by the figure that these ovules were, some of them, polliniferous, like those of the Passiflora, &c., described at p. 185, but nothing is stated on the subject.

See also section on Regular Peloria, Substitution, Pistillody of the stamens, &c.

CHAPTER V.
ALTERATIONS IN THE DIRECTION OF ORGANS.

The deviations from the ordinary direction of organs partake for the most part more of the nature of variations than of absolute malposition or displacement. It must also be borne in mind how frequently the direction of the leaves, or of the flower, varies according to the stage of development which it has arrived at, to unequal or disproportionate growth of some parts, or to the presence of some impediment either accidental or resulting from the natural growth of the plant. These and other causes tend to alter the direction of parts very materially.

Change in the direction of axile organs, roots, stems, &c.—The roots frequently exhibit good illustrations of the effect of the causes above mentioned in altering the natural direction. The roots are put out of their course by meeting with any obstacle in their way. Almost the only exception to the rule in accordance with which roots descend under natural circumstances, is that furnished by Trapa natans, the roots of which in germination are directed upwards towards the surface of the water. So in Sechium edule, the seed of which germinates while still in the fruit, the roots are necessarily, owing to the inverted position of the embryo, directed upwards in the first instance.

A downward direction of the stem or branches occurs in many weak-stemmed plants growing upon rocks or walls, or in trees with very long slender branches as in Salix Babylonica, and the condition may often be produced artificially as in the weeping ash.

The opposite change occurs in what are termed fastigiate varieties, where the branches, in place of assuming more or less of a horizontal direction, become erect and nearly parallel with the main stem as in the Lombardy poplar, which is supposed to be merely a form of the black Italian poplar.

M. de Selys-Longchamps has described a similar occurrence in another species of Poplar (P. virginiana Desf.), and amongst a number of seedling plants fastigiate varieties may frequently be found, which may be perpetuated by cuttings or grafts, or sometimes even by seed; hence the origin of fastigiate varieties of elms, oaks, thorns, chestnuts, and other plants which may be met with in the nurseries.

Sometimes when the top of the main stem is destroyed by disease or accident, one of the heretofore lateral shoots takes its place, and continues the development of the tree in the original direction. It is often an object with the gardener to restore the symmetry of an injured tree so that its beauty may ultimately not be impaired.[210]

Climate appears sometimes to have some influence on the direction of branches, thus Dr. Falconer, as quoted by Darwin,[211] relates that in the hotter parts of India "the English Ribston-pippin apple, a Himalayan oak, a Prunus and a Pyrus all assume a fastigiate or pyramidal habit, and this fact is the more interesting as a Chinese tropical species of Pyrus naturally has this habit of growth. Nevertheless many of the fastigiate varieties seen in gardens have originated in this country by variation of seeds or buds."

M. CarriÈre has also recorded a curious circumstance with reference to the fastigiate variety of the false acacia Robinia pseudacacia; he states that if a cutting or a graft be taken from the upper portion of the tree, the fastigiate habit will be reproduced, and the branches will be furrowed and covered with short prickles; but if the plant be multiplied by detaching portions of the root-stock, then instead of getting a pyramidal tree with erect branches, a spreading bushy shrub is produced, with more or less horizontal, cylindrical branches, destitute of prickles.[212]

Eversion of the axis.—In the case of the fig, the peculiar inflorescence is usually explained on the supposition that the termination of the axis becomes concave, during growth, bearing the true flowers in the hollow thus formed. The cavity in this case would probably be due not to any real process of excavation, but to a disproportionate growth of the outer as contrasted with the central parts of the fig. Some species of Sempervivum have a similar mode of growth, so that ultimately a kind of tube is formed, lined by the leaves, the central and innermost being the youngest. The hip of the Rose may be explained in a similar manner by the greater proportionate growth of the outer as contrasted with the central portions of the apex of the flower-stalk. In cases of median prolification, already referred to, the process is reversed, the central portions then elongate into a shoot and no cavity is formed. A fig observed by Zuccarini (figs. 105, 106) appears to have been formed in a similar manner, the flower-bearing summit of the stalk not being contracted as usual, the flowers projected beyond the orifice of the fig. If this view be correct the case would be one rather of lengthening of the axis than of absolute eversion since it was never inverted.

Fig. 105.—Fig showing prolonged inflorescence and projecting flowers.

One of the most singular instances of an inverted direction of the leaves is that presented by a turnip (fig. 107) presented to the Museum of King's College, London, by the late Professor Edward Forbes. The turnip is hollow in the interior and the majority of the leaves springing from its apex instead of ascending into the light and air become bent downwards so as to occupy the cavity, and in such a manner as to bring to mind the position of an inverted embryo in a seed.

Altered direction of the flower and its parts.—The changes which take place in the relative position either of the flower as a whole or of its several parts during growth are well known, as also are the relations which some of these movements bear to the process of fertilisation, so that but little space need here be given to the subject beyond what is necessary to point out the frequent changes of direction which necessarily accompany various deviations from the ordinary form and arrangement of parts.

In cases where an habitually irregular flower becomes regular, the change in form is frequently associated with an alteration in direction both of the flower as a whole and, to a greater or less extent, of its individual members, for instance of Gloxinia, the normal flowers of which are irregular and pendent, there is now in common cultivation a peloriate race in which the flowers are regular in form and erect in position.

Fig. 108 shows the usual irregular form of Gloxinia, with which may be contrasted figs. 109, 110 and 111.

Fig. 109 shows the regular erect form; fig. 110 the calyx of the same flower; while in fig. 111 are shown the stamens and style of the two plants respectively. In the upper figure the style of the peloriate variety is shown as nearly straight, and the stamens undergo a corresponding change. No doubt the relative fertility and capacity for impregnation of the two varieties is affected in proportion to the change of form. The Gloxinia affords an instance of regular congenital peloria in which the regularity of form and the erect direction are due to an arrest, not of growth, but of development, in consequence of which the changes that ordinarily ensue during the progress of the flower from its juvenile to its fully formed condition do not take place.

A similar alteration accompanies this form of peloria in other flowers (see Peloria). A change in direction may result also from other circumstances than those just alluded to. Abortion or suppression of organs will induce such an alteration; thus in a flower of Pelargonium now before me three of the five carpels, from some cause or other, are abortive and much smaller than usual, and the style and the beak-like torus are bent downwards towards the stunted carpels instead of being, as they usually are, straight.

Amongst orchids, where the pedicel of the flower or the ovary is normally twisted, so that the labellum occupies the anterior or inferior part of the flower, it frequently happens, in cases of peloria and other changes, that the primitive position is retained, the twist does not take place, and so with other resupinate flowers. In Azaleas a curious deflexion of the parts of the flower may occasionally be met with. Fig. 112 shows an instance of this in which the corolla, the stamens and the style were abruptly bent downwards: as young flowers of this singular variety have not been examined it is difficult to form an opinion as to the cause of this variation. In one plant the change occurred in connection with the suppression of all the flowers but one in the cluster, or rather the place of the flowers was occupied by an equal number of leafy shoots.

Moquin[213] mentions a flower of Rosa alpina in which two of the petals were erect, while the remaining ones were much larger and expanded horizontally. The same author quotes from M. Desmoulins the case of a species of Orobanche, in which a disjunction of the petals constituting the upper lip took place, thus liberating the style and allowing it to assume a vertical direction.

M. CarriÈre[214] has described an instance wherein two apples were joined together, a larger and a smaller one; the former was directed away from the centre of the tree as usual, while the smaller one was pointed in exactly the opposite direction. The larger fruit had the customary parchment-like carpels, the smaller was destitute of them.

Sometimes the direction assumed by one flower as an abnormal occurrence is the same as that which is proper to an allied species or genus under natural circumstances; thus flowers of the vine (Vitis) have been met with in which the petals were spreading like a star (fleurs avalidouires), as in the genus Cissus.[215]

Morren describes a curious condition in some flowers of Cuphea miniata, in which the placenta protruded through an orifice in the ovary, and losing the horizontal direction became erect (figs. 113, 114). A similar occurrence happened in Lobelia erinus. To this condition the Belgian savant gave the name of gymnaxony.[216]