THE ORDER COMPOSITÆ: ILLUSTRATED BY THE SUCCORY, THE SOWTHISTLE, THE DANDELION, THE BURDOCK, THE DAISY, THE CHRYSANTHEMUM, FEVERFEW, PELLITORY OF SPAIN, WILD CHAMOMILE, TRUE CHAMOMILE, YARROW, THE BUR-MARIGOLD, GROUNDSEL, RAGWORT, BIRD’s TONGUE, PURPLE JACOBÆA, CINERARIA, SUNFLOWER, MUTISIA, AND TRIPTILION.

The plants composing the order CompositÆ have all compound flowers, which differ from other flowers as much as a compound leaf does from a simple one. As the compound leaf is composed of a number of leaflets or pinnÆ united by a common petiole; so a compound flower is composed of a number of florets, united by a common receptacle, which is surrounded by a calyx-like involucre, so as to give the whole mass the appearance of a simple flower. Each floret has a calyx, the tubular part of which is rarely sufficiently distinct to be perceptible, but the limb is generally cut into long feathery segments called pappus. The ovary of each floret contains only one seed; and the fruit, which is called an achenium, retains the pappus when ripe, and falls without opening. There are five stamens, the filaments of which are distinct, but the anthers grow together so as to form a kind of cylinder, through which passes the style, ending in a two-lobed stigma (see a in fig. 41). Most of the corollas are of two Fig.41.—Ligulate floret of wild Lettuce. kinds: viz. the ligulate, as exemplified in the floret of the wild Lettuce (Lactuca virosa) shown in fig. 41; and the tubular, as shown in a floret of the Cotton-thistle (Onopordium Acanthium) see fig. 42. All the British species of CompositÆ have their florets either entirely of one of these kinds, or of the two mixed together; but some foreign genera have florets with two equal lips, cut Fig.42.—Tubular floret of the Cotton-thistle. into three or four lobes, as shown in a floret of Mutisia latifolia, at (e), fig. 46, p. 108. These florets are called bilabiate. It will be observed that in all these examples, as indeed, in all the flowers belonging to the order, that the pappus (b, in figs. 41 and 42), is always on the outside of the corolla, thus plainly indicating its connexion with the calyx.

The order CompositÆ is a very large one, above seven thousand species having been named and described; and to assist the memory in retaining the names of this great number of plants, various means have been devised for dividing the order into sections and tribes. The principal botanists who have proposed means of arranging this order, are Cassini, Lessing, and lastly the late Professor De Candolle, in three volumes of his Prodromus published in 1840. But as the distinctions between the divisions proposed, lie in the difference found in the stigmas and pappus of the different genera, I have judged them too troublesome for my readers, as I am sure they are for myself, and I have preferred following the plan adopted by Dr. Lindley in his Elements of Botany, published in 1841, and dividing the CompositÆ into four tribes; viz., the three originally proposed by Jussieu, and a fourth added by Professor De Candolle, containing the plants with bilabiate florets, which were either not known, or overlooked, by Jussieu. It may perhaps be necessary to add, that this arrangement forms the basis of the new one proposed by De Candolle, and that the principal difference consists in the subdivisions.

TRIBE I.—CICHORACEÆ.

Florets ligulate. Juice milky, narcotic.

The plants contained in this tribe bear more or less resemblance to the common Succory (Cichorium Intybus). This beautiful plant, which is found in great abundance wild in many of the sandy and chalky districts of England, has large bright blue flowers, which when examined will be found to consist of a number of florets, all of the kind called ligulate, that is somewhat like a cornet of paper; the upper part being broad and flat, and serrated at the edge. The pappus in this genus is very short, and it is scaly rather than feathery. The leaves are bitter, and when broken give out a milky juice; and the fleshy roots when roasted are used to adulterate coffee. The Endive is a variety of this species, or another species of the same genus. The Sowthistle (Sonchus oleraceus) abounds in the same milky juice as the succory, and has the same kind of fleshy root. The flower is composed of a scaly involucre (shown at a in fig. 43) and a number of ligulate florets (see b), which when they fall show the pappus (c), forming a feathery ball. The manner in which the pappus is attached to the seed-vessel is shown at (d); and the receptacle after the florets have been pulled out, but with the involucre still Fig.44.—Seed of the Dandelion. attached to it, at (e). A detached floret is shown at (f). The Dandelion (Leontodon Taraxacum) differs from the Sowthistle: in its florets, which are flatter and looser; in its receptacle, which is globular; and above all, in its pappus, which is what is called stipitate or stalked, that is, the tubular part of its calyx rises to a considerable height above the capsule, before it becomes divided into its feathery segments, as shown in fig. 44. The leaves of this plant are what is called runcinate, that is, the lobes into which they are cut point downwards towards the root instead of upwards from it, and the root is also fleshy. The Lettuce, Salsafy or Goat’s-beard, Ox-tongue, Hawkweed, Cat’s-ear, Nipplewort or Swine’s Succory, and many other well-known plants, belong to this tribe.

TRIBE II.—CYNAROCEPHALÆ.

Florets tubular. Juice watery, tonic.

The plants in this division all bear more or less relation to the common Artichoke (Cynara Scolymus). The scales of the involucre are generally fleshy at the base, but terminate outwardly in a sharp hard point. The florets are tubular, and intermixed with them in the receptacle are frequently found the hardened bracts, which in this state are called paleÆ, and which appear to be of a chaffy substance, as exemplified in the choke of the Artichoke, the fleshy receptacle being in this plant what we call the Artichoke bottom. This peculiar formation is shown more in detail in fig. 45, which represents Fig.45.—Part of the flower-head of the Burdock. part of the flower of the common Bur or Burdock (Arctium Lappa), so annoying from the strong hold it takes of any part of the dress which it may chance to touch. In fig. 45 a is the involucre, every scale in which is hooked and turned inwards, so as to hold firmly whatever it may catch; b is a floret showing its tubular shape, and its style proceeding through the united anthers; c shows the hardened bracts or paleÆ, the other florets having been removed; and d shows a fruit with a palea attached, magnified. All the different kinds of thistle belong to this division; and though many of the kinds have not the hardened bracts, they have all a spiny involucre. The pappus of the thistle is generally attached to a kind of disk, from which it becomes loosened soon after the seed falls, and this thistle, down, as it is called, being extremely light, is blown about by the winds. All the thistles have fleshy roots, and take firm hold of the soil. The Corn Blue-bottles (Centaurea), the Wild Saffron (Carthamus tinctoria), and many other well-known plants, belong to this division.

TRIBE III.—CORYMBIFERÆ.

Florets partly tubular and partly ligulate; juice watery; sometimes bitter and tonic, and sometimes acrid. The seeds of some of the species yield oil.

The plants included in this tribe all bear more or less resemblance to the common Daisy. In this well-known flower, the white florets are all ligulate, and compose what is called the ray, and the yellow flowers, which are tubular, are called the disk. The involucre is simple and leafy, and the receptacle is conical. The seeds are without pappus. The Chrysanthemum is nearly allied to the Daisy, and its seeds also are destitute of pappus; but it is easily distinguished by its involucre, which is scaly, and by the flower forming a kind of depressed globe in the bud. The scales of the involucre are strongly marked, from being edged with a thin membrane, and the florets of the ray are much longer in proportion to those of the disk than in the Daisy. The great Ox-eye Daisy, which was formerly called Chrysanthemum leucanthemum, is now placed in a new genus, and called Leucanthemum vulgare; and the Chinese Chrysanthemums have been removed to the genus Pyrethrum. Both plants, however, will no doubt long continue to be called by their old names. The beautiful yellow-flowered plant often found growing among corn (Chrysanthemum segetum), the three-coloured Chrysanthemum (C. tricolor or carinatum), and the yellow annual Chrysanthemum (C. coronarium), with some others, have been left by Professor De Candolle in their old genus. In the Feverfew (Pyrethrum), the receptacle is elevated, and the fruit is crowned with a narrow membrane. The Pellitory of Spain was formerly considered to belong to this genus, and afterwards to the Chamomile, but it is now called Anacyclus Pyrethrum. Matricaria Chamomilla, the wild Chamomile, has also no pappus; and in this plant the receptacle is almost cylindrical. The true Chamomile (Anthemis nobilis) greatly resembles the Chrysanthemum in its flowers; but they are distinguished by having a chaffy receptacle, and the fruit having a membranous margin. The smell of the Chamomile is aromatic, and its qualities highly tonic. The Yarrow (Achillea millefolium) is another plant destitute of pappus, but with a chaffy receptacle; it is also remarkable for its leaves, which are doubly pinnatifid.

It will be seen by the above enumeration, that in many plants belonging to this division, the pappus is entirely wanting, and in others it will be found to assume a different form to that which it bears in the other tribes. Thus, in the Bur-Marigold (Bidens), the pappus consists of from two to five erect awns, which are covered with very small, bent bristles. The genus Senecio has soft, hairy pappus, as may be seen in the common Groundsel (S. vulgaris); the leaves of this weed are pinnatifid, and somewhat stem-clasping, and the flowers have no ray florets. In other species of this division, however, the ray florets are very conspicuous: as, for example, in the common yellow Ragwort (S. JacobÆa), in the great fen Ragwort, or Bird’s tongue (S. paludosa), and in the purple JacobÆa (S. elegans). Nearly allied to Senecio, is the genus Cineraria, so much, indeed, that Professor De Candolle, in his late arrangement of the CompositÆ, has included the greater part of the species in Senecio. The greenhouse species, with purple flowers, are among those which have been changed; but they will probably always retain the appellation of Cineraria, as an arbitrary English name. The Asters, or Michaelmas Daisies, Golden Rod, Elecampane, Leopard’s Bane, the Cape Marigold, (now called Dimorphortheca, instead of being included in the genus Calendula), Coltsfoot, Wormwood, Southern-wood, Tansy, and many other well-known plants, belong to this division.

The Sunflower (Helianthemum annuus) is an example of one of the plants belonging to this division which has seeds yielding oil. In this plant the pappus is awl-shaped, and deciduous; and the receptacle, which is broad and somewhat convex, is paleaceous. The seeds are large and oblong, and when pressed, yield a considerable quantity of oil. The Madia is another oil plant; and indeed the seeds of several in this division yield oil.

TRIBE IV.—LABIATÆFLORÆ.

Florets bilabiate.

The plants belonging to this division are rarely seen in British gardens; but when they do occur, they are well worth examining, from the singularity of their formation. Mutisialatifolia (see fig. 46) has a large, woolly involucre, the Fig.46.—Flower and Leaf of Mutisia Latifolia. scales of which are of two kinds, the outer ones, (a), being pointed and leaf-like, and the inner ones, (b), having the appearance of scaly bracts. The florets of the ray, (c), are narrow, and spreading in the fully expanded flower; and those of the disk, (d), are shorter, erect, divided into two lips, which curl back, and the lower one of which is again divided into two segments (as shown at e in the detached floret). The leaves of this plant are very curious; the midrib is lengthened and drawn out into a tendril, as shown at f, and the petiole (g) is decurrent. There are several other genera belonging to this tribe, but none of them are particularly ornamental except Triptilion spinosum, which has flowers of the most brilliant blue, that do not lose the intensity of their colour in drying.