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W.West. imp

Sowerby.Dc

Winter Life of Plants.

form a series of annuli or rings, for which botanists have no name, and which we have ventured to call (gemma vestigia) vestiges of buds. Whenever these rings are found on the bark of young shoots, they show the position of the winter leaves and the terminal bud of the season,-in fact, the point where the growing shoot entered on the stage of rest. Hence the interval of shoot between two sets of bud-rings shows one year's growth; and therefore the number of sets of annuli shows the age of the shoot.

The reader will better understand our meaning if he will look at the plate which accompanies this paper.

Plate IX., fig. 1, represents one year's growth of the beechtree (Fagus sylvatica), with five buds and their spirally arranged scales or winter leaves. The cicatrix or leaf-scar s, left by the summer leaf, is visible at the base of each bud; and the annular scars left by the winter leaves of the previous year are to be seen at the base of this shoot, marked a.

These parts are more conspicuous in fig. 2, which shows two shoots of the horse-chestnut tree (Esculus hippocastanum), one the growth of a single year, the other the growth of ten years; yet both shoots are nearly the same size. We have placed them together for the sake of comparison.

The leaf-scar 8, left by the nutritive summer leaves, is very large in the horse-chestnut, and on its surface are seven black dots, the broken ends of the fasciculi, or bundles of woody fibre, which, uniting together, form the leaf-stalk, and, separating again at its top, form the costa or midribs of the seven leaflets. This tree derives its popular name from the resemblance of its leaf-scar to the shoe of the horse, those black dots corresponding with the nails in the shoe!

In the ten years' shoot it will be seen that there are on the scars of the summer leaves only five dots; consequently there were only five leaflets to each leaf. The contrast between the broad open scar left by the summer leaves and the contracted ring-like scars of the winter leaves, is in this instance very striking. It is also evident that the vegetative power of the ten years' shoot was ten times less each year than that of the one year's shoot; because it has taken this shoot ten years to make a growth equal to the growth of the one year's shoot. As the growth of the shoot depends on the matter derived from the leaves, and as in this case very little was supplied, the shoot itself is cylindrical, not conical, like the one year's shoot.

Fig. 3 is a twig of the tulip poplar (Liriodendron tulipifera), one of the forest trees of North America. The leaf-packing in this bud is peculiar and interesting. c represents the closed stipular bud; d, a stipular bud opened, with the two stipules reflected downwards, to show the inverted position of the

lamina or blade of the embryo leaf l, the two sides of which are folded together and which is bent downwards on its petiole. Behind is another stipular bud consisting of two stipules inclosing another inverted embryo leaf. Further dissection reveals other embryo leaves on a constantly diminishing scale of architecture, b, the linear mark on the shoot, or scar made by the stipular leaves, which are, in fact, only another variety of winter leaves. There are seven dots on the leaf-scar.

These shoots were collected in autumn. The Liriodendron tulipifera, which is a deciduous-leaved tree, has still attached to its apex one of its leaves, which is purposely left there, in order to give the reader a correct idea of its peculiar truncated form, and also a clear view of the embryo leaf b.

The lower and less developed herbaceous plants have also a winter's life and an appropriate shelter for that life, as well as the trees. The seeds of annuals and also the rhizomes, or underground stems of perennials, like the buds of trees, are only so many winter retreats into which the exhausted life of these plants retires for protection, repose, and recuperation during the winter months. "Seeds and resting-spores," says Henfrey, "are organized in a manner especially adapted to preserve their latent vitality from injury by external influences. They can withstand great variations of heat or cold, especially in the absence of moisture. Most seeds will bear a temperature very far below the freezing-point if kept dry, and many will bear an exposure to 100° or 110° Fahr. in dry sand. Prolonged immersion in water at 120° kills most seeds unless the skin is very thick and they contain oil instead of starch in their endosperm."

The seeds of the Whitlow-grass (Draba verna), of the different species of chickweed (Cerastium and Stellaria), of the fumitory and corn-cockle, are sown early, and are, therefore, exposed to the excessive heats of summer as well as to the cold of winter, and yet they come up at their appointed season. So carefully has Nature prepared the seeds of these plants for the vicissitudes to which they are exposed! Druba verna, for example, is never scarce. This plant is quite common in Pennsylvania, as well as in England. There is no flower which has interested the writer more than this

lowly annual. It is one of the least developed of all the Cruciferæ, whether we consider its leaves, whose vegetative power is so enfeebled that they do not form a sufficient amount of stem to separate them from each other, but remain in a stellate cluster on the ground; its tender capillary scape, or flower-stem, which only rises to a height of from one to three inches above the ground; the two or three small white flowers which that scape supports; or the brevity of its life,

for it comes up in March, and by the close of April has matured and scattered its seeds. Yet these minute seeds, with their microscopic rudiment of a plant, are mixed with the soil, from which they cannot be distinguished, and after lying exposed alike to the heat of summer and the cold of winter, germinate again at the appointed time on our rocks and old walls. In Pennsylvania, where the extremes of heat and cold are much more severe than in England, Draba verna grows profusely, and the writer has seen the gneiss rocks about Philadelphia positively overspread with whitened patches of this little plant, towards the close of the month of March.

But the greater portion of the herbaceous plants are perennials, whose leaves and flowers annually die down to their rhizome or underground stem, and, therefore, disappear like the annuals from the earth's surface in winter. But life remains in the rhizome, and the next year's growth is contained within the buds on the surface. The soil in this case shelters the buds. Hence, as soon as the frost is out of the ground, the plants which have been thus protected, issue forth from these subterranean buds, push up through the soil into the atmosphere, and again unfold their leaves and flowers on the same spot. Perennial plants, having the rhizome and bulb as a means of self-preservation, as might be naturally supposed, are not so prolific in seed as annuals.

The period of seed-rest or vegetable torpor may be prolonged for years, if there are not the conditions necessary for germination. For sixty years a bag of plants supplied the "Jardin des Plantes " annually with sensitive plants. Lindley mentions the germination of raspberry seeds, found in 1834, in an ancient barrow (tumulus), near Maiden Castle, along with coins of the emperor Hadrian. The seeds were found in a coffin thirty feet below the surface, and may have been from 1,600 to 1,700 years old.

It is thus that the germs of vegetable life are preserved. The Winter-life of Plants! It is one of slumber and inactivity, comparatively speaking, yet how deeply interesting its preservation. What, though the trees have on at present only their plain unattractive garb of winter leaves, yet their more ornamental summer-leaf dress has been carefully prepared for them, and now lies folded up in the bud,-the wardrobe of Nature! They will put it on uninjured at the appointed time! What matters it that the fierce north winds sweep the landscape of all its visible life and fertility, and extend still farther and farther the snowy territories of winter? The flowers are all safely sheltered in their winter home,

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