THE CATKIN-BEARING TREES: ILLUSTRATED BY THE WALNUT, THE HICKORY, THE WILLOW, THE POPLAR, THE ALDER, THE BIRCH, THE OAK, THE BEECH, THE SWEET CHESTNUT, THE HAZEL, THE HORNBEAM, THE HOP HORNBEAM, THE PLANE TREES, THE LIQUIDAMBAR, MYRICA, COMPTONIA, CASUARINA, AND Garrya elliptica.

The plants contained in this chapter are placed by modern botanists in six or seven different orders; but I have been induced to group them together, both because they follow each other in regular succession, and because there is a certain degree of general resemblance which connects them together, and renders it easier to retain their names when linked together by the association of ideas, than it would have been if they had been each described separately.

The first order of catkin-bearing trees that I shall describe is called JuglandaceÆ, and it contains three genera, only two of which, the Walnuts and the Hickories, are common in British gardens. The second order, SalicaceÆ, contains also two genera, the Willows and the Poplars; the third, BetulaceÆ, contains both the Alders and the Birch trees; the fourth, CorylaceÆ or CupuliferÆ, contains the Oak, the Beech, the sweet Chestnut, the Hazel, and the Hornbeam; the fifth, PlatanaceÆ, is generally considered to include two genera; viz., Platanus and Liquidambar, though this last is, by some botanists, placed in a separate order called BalsamaceÆ; and the sixth, MyricaceÆ, or the sweet Gale family. All the genera included in these orders, with the exception of those belonging to JuglandaceÆ, were formerly comprised in one order, which was called AmentaceÆ; from the word Amentum, which signifies a catkin. The seventh and last order I have mentioned in this chapter is called GarryaceÆ, and consists of one single genus, Garrya, only lately known in Europe. Of all these orders the largest and most important is CupuliferÆ, as it includes, among other valuable trees, the Oak and the Beech. All the plants mentioned in this chapter have their male and female flowers distinct, many of the genera having them on different plants; and the male flowers are always in catkins, generally long and cylindrical, but sometimes round and ball-shaped. The female flowers are sometimes in catkins also, but sometimes they are produced singly or in pairs. The flowers of both kinds are without petals, or with such as are inconspicuous; and sometimes without even a calyx, but they are always fur nished with bracts, which grow so closely to the flower as almost to seem a part of it. The ovaries are generally two-celled, but they rarely remain so, as they become one-celled before the seed is ripe. The style is, in most cases, very short, and the stigma generally two-lobed. The leaves are always alternate, and generally simple, except in the case of the JuglandaceÆ. They are all hardy trees and shrubs.

JUGLANDACEÆ.—THE WALNUT TRIBE.

The genera belonging to this order have compound leaves, and the male flowers in long cylindrical catkins; the male and female flowers being on the same plant.

THE GENUS JUGLANS.

This genus consists of only three species: the common Walnut (J. regia); the black Walnut (J. nigra); and the Butter-nut (J. cinerea or cathartica). The male and female flowers are distinct, but on the same plant: the male flowers being produced in long, solitary, cylindrical catkins, and the female ones in pairs, or in shorter catkins. The leaves are pinnate, with the leaflets not always opposite, which is very rarely the case in other plants. In Juglans regia (the common walnut), the male flowers are produced in a very thick catkin, each flower consisting of Fig.77—Walnut (Juglans regia). a calyx divided into five or six scale-like lobes, and generally from twelve to twenty stamens, with very long anthers and very short filaments; there is also a very curious bract to each, as shown in the magnified flower at a in fig. 77; in which the anthers are seen at b. The female flowers are in pairs, as shown at c; and they consist of a calyx, d, enclosing the ovary, and toothed in the upper part, and four small petals encircling two large thick leafy-looking stigmas, e.

The fruit is a fleshy husk in one piece, formed of the dilated calyx; it generally retains the stigmas till it has nearly attained its full size, and when it becomes ripe it does not separate into valves, but bursts irregularly. The nut, on the contrary, is in two distinct valves, which may be easily separated from each other; and it is imperfectly divided into cells by four half dissepiments. The germ of the future plant is what children call the heart, and it is in the upper part of the kernel, with the root end uppermost, so that when a walnut is sown the sharp end should be placed downwards. The kernel is four-lobed, and deeply wrinkled; and when the young plant begins to grow, it divides into two cotyledons or seed-leaves, which drop off when the true leaves are fully developed. The kernel is covered with a thick skin, which is very astringent; and the nut is covered with a membranaceous network of strong veins, which are generally found in a withered state on opening the ripe husk, having left their impression deeply imprinted on the outside of the shell of the walnut. The leaves are impari-pinnate, consisting of four pairs of leaflets and a terminal single one; the lower pair of leaflets is much the smallest, and the other leaflets are frequently not opposite; and they are sometimes unequal at the base. The main petiole is dilated at the point where it joins the stem; and the leaves are placed alternately. The tree is large and widely spreading; and the timber is of a close grain, and takes a fine polish.

The Black Walnut (J. nigra) differs from the common kind, in the male Fig.78.—Leaf and fruit of the Black Walnut (Juglans nigra). flowers being on a smaller and more slender catkin, and furnished with a brown roundish bract at the back of the calyx. The female flowers are also in a sort of catkin, and four or five together. The fruit (see a in fig. 78) is round, and the husk very thick at first, but it gradually wastes away, when the seed is ripe, instead of opening. The leaves have seven or more pairs of leaflets, which are generally nearly opposite, and sometimes they are without the terminal single leaflet, as shown at b. The shell of the nut is very hard, and the dissepiments, which are also very hard, are generally perfect, and divide the kernel into four parts. The nuts should be sown as soon as possible after they are ripe, as they will not keep good above six months. The tree grows above seventy feet high, and the wood is very hard and black.

The Butter-nut (J. cathartica) resembles the Common Walnut in its male catkins, except that they are produced upon the old wood instead of being on the wood of the present year. The Fig.79.—Butter-nut(Juglans cathartica). female flowers grow four or five together in a short catkin, and they are distinguished by their stigmas, which are rose-coloured. The fruit (a in fig. 79) is pear-shaped, ending in a rather long point; and the kernel of the nut (b) resembles that of the Common Walnut, except in being more oily. The leaves (c) are like those of the Black Walnut, except that the leaflets are rather downy, and that there is a terminal one. The calyx of the female flower is also covered with a viscid down, which remains on the husk of the ripe fruit; and the shell of the nut is very hard and very much furrowed. The tree is of much smaller size than that of the Black Walnut, and it may be easily distinguished by the greyness of the bark of its young shoots; it also comes into leaf earlier, and the nuts are ripe about a fortnight sooner than the others. The wood is light, of a reddish colour, and rather a coarse grain.

THE GENUS CARYA.

The genus Carya (the Hickory) consists of ten or twelve species, which greatly resemble Fig.80.—Thick-shell Bark Hickory
(Carya lacinosa). the Walnuts in their general appearance, but are distinguished by the male catkins, instead of being solitary, being produced in tufts or bunches, three or more on each peduncle. The stigma is also frequently four-lobed, and the husk, when ripe, divides into four equal valves, which in some of the species are very thick, as in the Thick-shell bark Hickory (see a in fig. 80). The nut (b) is not valved, and it is either not furrowed, or very slightly so; but it has four angles which are more or less distinct in the different species: the shell and the dissepiments are both very hard, and the latter, as in the Mocker nut, are sometimes entire, so as to render it very difficult to extract the kernel. The leaves (c) resemble those of the walnut; but they are generally of a thinner texture, and somewhat downy, the down being disposed in little tufts, as may be seen by a microscope. The trees vary much in size, but all of them have a reticulated bark. The wood is of a coarse grain, and will not polish; but it is very strong, and so remarkably tough that it is hardly possible to break it.

There is only one other genus in the order JuglandaceÆ, and that consists of only a single species, Pterocarya caucasica. It has pinnate leaves of nineteen leaflets each, placed as closely as possible together; and the fruit, (that is, the husk,) is spread out on each side into a thin membrane or wing. This plant is sometimes called Juglans fraxinifolia.

SALICACEÆ.—THE WILLOW TRIBE.

The plants contained in this order have simple leaves, and the male and female flowers on different plants, both in upright cylindrical catkins.

THE GENUS SALIX.

The genus Salix (the Willow) contains perhaps more species than any other, above two hundred and fifty having been named and described, besides innumerable varieties. The plants included in the genus may, however, be all divided into three kinds—viz. the true Willows, which have thin green leaves, and which include all the tree species, most of which have brittle branches; the Osiers, the leaves of which resemble those of the Willows, but which are low shrubs with very tough branches; and the Sallows, the leaves of which are thick and woolly or shaggy. The Osiers and the true Willows are often confounded together; particularly when the former take, as they sometimes do, a tree-like character; but the Sallows are always perfectly distinct. The rods of the Osiers are used in basket-making.

All the species of the genus have their male and female flowers on different plants, both kinds of flowers being placed on short catkins which are either erect or spreading sideways. The male flowers have each from one to five or more stamens, with no petals or calyx, but as a substitute a bract or scale, which is entire and hairy, and which has one or more glands at its base. The female flower has a similar bract or scale, and it is also without either petals or calyx; there are two stigmas, each of which is sometimes two-lobed. The capsule has only one cell, but many seeds which are covered with down or longish hairs, and which are very conspicuous from the capsule opening naturally into two valves when ripe. The leaves of the Osiers and Willows are generally lanceolate, and serrated at the margin, and they are always furnished with stipules; but the leaves of the Sallows are generally much broader, and sometimes roundish; and they are always of a thick velvety texture. Though the number of the stamens varies in the different species, two are by far the most common.

Fig.81.—The Willow (Salix). Fig. 81 shows the female flower of Salix fragilis at a, b is the honey gland, c the stigma, which is divided into four equal parts, and d the bract or scale with its hairy fringe; e is the male flower with its two stamens, two glands, and hairy scale. This species is a tall, bushy-headed tree, with the branches crossing each other frequently, being set on obliquely; and it is called the Crack Willow, from the young branches separating from the trunk in spring with the slightest blow or jerk, their bases being as brittle as glass. The leaves are of a deep green. The White Willow (Salix alba) differs from the preceding species in the branches being widely spreading and somewhat drooping, the old bark cracked into deep fissures, and the foliage of a silvery grey, owing to the silky hairs with which the leaves are more or less covered. The wood of the Tree Willows is soft and white, and very elastic; it is therefore used for cricket-bats, mallets, and other purposes where wood is wanted to resist a hard blow. S. vitellina, the Golden Osier, is so called from its golden-coloured bark; and S. purpurea, the Purple Willow, is so called from the colour of its branches. This last species has only one stamen; but as the anther is four-celled, it is probably two stamens grown together. All the species that have only one stamen have a four-celled anther, as for example the Rose Willow (S. Helix), which has the female catkins red. Salix caprea, the great round-leaved Sallow or Palm Willow, is perhaps the handsomest species, from the great abundance and golden hue of its flowers.

THE GENUS POPULUS.

The genus Populus (the Poplar) is distinguished from Salix by the bracts of the flowers being deeply cut instead of being entire; by both the male and female flowers having a calyx; and by the male flowers never having less than eight stamens. The leaf-buds are also covered with numerous scales. Fig. 82, a, shows the stamens of the Trembling Poplar or Aspen (Populus tremula) shrouded in their cup-like calyx, and with their laciniated bract; b shows the female flower with its four stigmas and deeply-cut bract; and c, the pod with its valves curling back, so as to show the downy covering of the seeds. All these parts are magnified to show them distinctly, as they are nearly the same in all the species. The following are the distinctions between the principal species. In the White Poplar, or Abele-tree (P. alba), the leaves are lobed, and covered with a white down on the under side. In P. canescens, the Grey Poplar, the leaves are also downy beneath; but they are roundish, and the female flower has eight stigmas instead of four. The Aspen (P. tremula) has four stigmas, with two leafy appendages at the base, which look like two other stigmas; and the petioles of the leaves, which are very long, are flattened, and so attached to the stem as to be twisted by the weight of the leaf when acted upon by the wind, which gives them their tremulous motion: these leaves are smooth on both sides. All these species have spreading roots, and send up a great many suckers; and their wood is used for butchers’ trays, pattens, bowls, milk-pails, and various other purposes. Populus nigra, the Black English Poplar, on the contrary, does not send up suckers, and its wood is of very little use; it is, however, very ornamental from the large size and great number of its male catkins, and the bracts of the flowers being of a brownish red, which gives them, when fallen, the appearance of the large brownish-red caterpillars of the Goat-moth. The Black Italian Poplar (P. monilifera) is remarkable for the quickness of its growth. The capsules of the female trees contain such a quantity of down attached to the seeds, as to render it quite unpleasant to walk under them when they are ripe. The Lombardy Poplar (P. fastigiata or dilatata) is remarkable for its upright and close habit of growth; its leaves also are very peculiar in their shape, being broad at the base and then tapering suddenly to a point. The seeds resemble those of the Black Italian Poplar in the quantity of wool which they produce, but luckily the female plants are extremely rare. There are many other species, the most remarkable of which are the Carolina Poplar (P. angulata), known by its square stem and very large leaves; the Balsam Poplar, or Tacamahac tree (P. balsamifera), the buds of which are covered with a resinous fragrant substance, and the leaves are of a pale yellowish green, appearing very early in spring; and the Ontario Poplar (P. candicans), which resembles the balsam Poplar, except in its leaves, which are very large and whitish on the under surface, and in the great rapidity of its growth, while that of the Balsam Poplar is rather slow.

BETULACEÆ.—THE BIRCH TRIBE.

The plants included in this tribe have single leaves, which are generally what is called feather-nerved; that is, the veins are marked strongly and deeply from the mid rib to the margin. The flowers are in cylindrical catkins, the male and female flowers being on the same plant.

THE GENUS BETULA.

The common Birch (Betula alba) is an exceedingly graceful tree. The male Fig.83.—Catkins of the Birch. catkins are produced singly, or two or three together. They are long, slender, loose, and gracefully drooping; (see fig. 83;) and each consists of a great number of flowers, pressed close together, and growing round a rachis or stem, as shown in the catkin a in fig. 84, from which some of the flowers have been removed. The male flowers Fig.84.—The Birch (Betula). have each ten or twelve stamens enclosed in three or more scales or bracts, as shown in a reversed flower at b. The female flowers are produced in dense catkins, which are much shorter than the others, and always solitary; the flowers, which are arranged round a very slender axis, are furnished with lobed scales, and c is a scale with three female flowers in its lobes, each having two long spreading stigmas (d). A ripe capsule is shown at e, with its membranaceous wings, and the cell f open to show the seed. The ovary when young has two cells and two ovules (as shown at g); but the division between the cells wastes away as the seeds ripen, and one of the ovules proves abortive. There are several species of Birch natives of America, some of which have upright oval female catkins like those of the Alder, but they are always distinguished by being solitary.

The bark of the Birch is remarkable for its tenacity, and for the great length of time that it will resist decay. In America they make canoes of the bark of B. papyracea; and in Lapland huts are thatched with that of B. alba. The Birch is remarkably hardy; and it grows nearer the limits of perpetual snow both on mountains and near the pole than any other tree.

THE GENUS ALNUS.

The Common Alder (Alnus glutinosa), though so nearly allied to the Birch botanically, differs widely in its habits; as it always grows in low marshy situations, or near water, while the Birch prefers the summits of the loftiest hills. In the Alder, the male catkins are long and drooping, like those of the Birch; but they are generally produced in clusters of three or more together. The male flowers are furnished with three lobed bracts or scales, each containing three flowers, each flower having a calyx of four scales united at the base, and bearing four stamens. The female flowers are in close ovate catkins, produced in clusters of four or five together, instead of being cylindrical and solitary, as in the Birch; the scales of the catkins, though three-lobed, are only two-flowered, and the flowers have two long stigmas like those of the Birch. The ovary has two cells and two ovules, but it only produces one seed. The ripe fruit is a nut without wings, attached at the base to the scale of the cone-like catkin, the scales of the catkin becoming rigid, and opening, like those of the Scotch Pine, as the seed ripens. There are several species of Alder, some of which bear considerable resemblance to the American species of Birch; but they are easily distinguished by the female catkins of the Birch being always solitary, while those of the Alder are produced in clusters, and by the capsules of the Alder being without wings.

CUPULIFERÆ—THE CUP-BEARING TREES.

This order includes six genera of very important trees; all of which have their ripe fruit shrouded in a cup-like involucre, which they retain till ripe. The male and female flowers are on the same plant.

THE GENUS QUERCUS.

The fruit of all the species of Oak is an acorn, which is only partly covered by a scaly involucre called the cup. The shape of the acorn, and the height to which it is covered by the cup, differ in the different species; but the general character of both is always the same.

The male catkins of the common British Oak (Quercus Robur pedunculata) are long and very few flowered; the flowers being small and very far apart. The flowers themselves have six or eight stamens and as many feathery bracts, which are united at the base. The female flowers (a in fig. 85) Fig.85.—The Oak. are produced on a long stalk at a distance from each other, and each consists of an ovary closely covered with a toothed calyx, as shown in the highly-magnified flower at Fig.86.—Germination of the Acorn. (c), and an involucre of several bracts or scales, (d); the style is short and thick, and the stigma (e) is three-lobed. As the fruit ripens, the style and stigma wither away, and the seed remains covered by the adnate calyx (b), which has become hard and shining. There is a circular mark or scar at the bottom of the acorn when taken out of its cup, which is called the hilum; and when the acorn is planted, this part should be kept upwards, as the foramen or part where the germ lies is at the other end. When the acorn begins to germinate, it opens at the foramen, cracking a little about half-way down, but not dividing entirely (see fig. 86). The root (a) then begins to protrude, and soon after the plumule, or young shoot (b), the leaves of which gradually unfold themselves. A curious experiment may be tried by suspending an acorn in a glass of water, or by placing it in one of those glasses with a wide mouth and a narrow neck, used for nosegays; when, if kept in a sitting-room, the acorn will gradually open, and the root and leaves develop themselves; and thus may be watched the first beginning of the monarch of the forest, the progress of which is so strikingly depicted in the beautiful lines adapted by Cowper to the hollow trunk of a gigantic oak in Yardley Chase near Castle Ashby:—

The leaves of the common Oak are deeply sinuated, and without footstalks, but those of Quercus Robur sessiliflora, another British Oak, are upon short footstalks, though the acorns are sessile. This last species predominated in the oak forest which formerly surrounded London; and many examples are still to be found at Lord Mansfield’s beautiful seat at Hampstead, the name of which, Ken wood, alludes to them, Ken being Saxon for an acorn. The wood of this tree was also used for the roof of Westminster Hall, and many other ancient buildings which till lately were supposed to be of Chestnut. Oak wood may always easily be tested by wetting a knife and then cutting it, when the astringent property in the Oak will turn the knife black, a result that will not take place with Chestnut.

There are nearly fifty species of Oaks which may be obtained in the British nurseries; the most remarkable of which are the Cork tree (Quercus Suber), the cork being the bark; the Evergreen Oak (Q. Ilex); the American Oaks, particularly the scarlet Oaks (Q. coccinea and Q. rubra), the Live Oak (Q. virens), and the Willow Oak, with long narrow entire leaves

(Q. Phellos); and the Turkey, Fulham, and Lucombe Oaks (Q. Cerris and its varieties). All Oak trees are very liable to be attacked by a species of gnat, and which produces excrescences on the branches. The oak apples of the British Oak, and the galls of Quercus infectoria, which are used in making ink, are of this nature. The Kermes, an excrescence found on Quercus coccifera, is the work of a kind of Coccus, similar to that which produces the cochineal on the Opuntia.

The timber of all the European Oaks is remarkably durable; but that of nearly all the American Oaks, except Quercus virens, is coarse grained, and so porous that it cannot be used for wine casks. The cork trees are generally grown in Spain; and as the cork when taken off the tree, curves round, it is laid upon the ground and kept flat with heavy stones; while a fire is made upon it with the branches, so as to heat it through, after which it remains flat when the stones are removed.

THE GENUS FAGUS.

Fig.87.—The Beech (Fagus).