T1VERY leaf is an elaborate machine, using the air as
material to work upon. From its first emergence from the bud it is a partner with the sun, living its life in the closest relations with the two greatest forces in the universe, the elements of light and air. From the sun it draws energy, and from the air material to build up the plant or the tree. Yet as distinguished from the tree it is another life, one of tens, or thousands, or myriads of lives that every year are born from the same mother, to live out their brief season, and gather for the tree the invisible spoils of sunlight and ether, to bestow them on the parent before they die. It is doubtful whether we should honour the tree and its vigour so
4 much as we do, while looking on the leaves as mere emblems of what is frail and fleeting ; for it is these same leaves that maintain the flow of life in the tree, and are the active and magical suppliers of daily growth. The tree is like the earth, and the leaves the children of earth, which are born of it and return to it again. But while the earth, like the tree, is the ultimate source of life, so the children of earth, or the leaves, the children of the tree, are the active "lives " in which the living principle is manifest.
Some leaves are so vast in size, in proportion to the plant which bears them, that they seem to have a personality of their own, such as we attribute almost spontaneously to the mighty frames of oak, or baobab, or soaring sequoia. In them we behold the active and living principle at work on a scale so large that, as the saying is, we can almost see them grow. In the water plants, especially those which lie on the surface of slow rivers and still lakes and pools, the leaf almost is the plant. From the water lilies of our ponds to the gigantic Victoria Regia from tropical America, the stems are merely thin connecting tubes between the leaf which is living and breathing on the surface, and the root which is drawing certain other sustenance from the mud and water down below. A Victoria Regia leaf is often six or seven feet in diameter, capable of supporting a man on its gigantic platter of green tissues, the surface of which " feeds " with wonderful rapidity on the supplies drawn from tropical sunlight and the humid equatorial air. Many of the bananas, again, have leaves which seem almost to make the tree. The stem is a mere supporting column, and there are no branches or branchlets, only the fan of enormous cool green leaves, sometimes nine feet long, and more than a third of that measurement in width, with a mid rib thicker than a golf club, and a leaf of even tissue, cool, fleshy, green as the grottos in asea cavern, and impervious to the most fiery arrows ever shot from the Sun Grad's quiver.
Our English climate does not feed the plants so bountifully. Probably the largest leaf produced in our fields is that of the prosaic but very useful "cow cabbage." People who smile at the idea of there being anything possibly interesting in a cabbage would not doubt the fact if they examined a field covered with these gigantic cruciferae. They are the embodiments of vegetable energy, growing so fast that it is difficult to leave enough space for the young plants to mature. One of them sometimes measures five feet across from the tips of the outer leaves, and weighs as much as forty pounds.
Among the leaves of our trees those of the horse-chestnut are probably the largest, though those of a sapling sycamore are not much inferior in size. It is noticed that the leaves of young sapling trees, or seedlings, which are not yet mature, and have not produced fruit, are far larger than those of older trees of the same kind. The leaves of a young horse-chestnut, now all golden yellow and ready to drop from the branch at the faintest breath of air, measured on an average one foot from the juncture of the mid rib with the top of the main stalk of the leaf.
The wonderful variety in the shape of leaves is among the chief sources of beauty in the world of plants. They vary from the " simple " egg-shaped leaf of the laurel or the indiarubber plant to the intricate and exquisite " cutting " seen in those of the maidenhair fern, the yellow briar-rose, the ac anthus, or the fig. The " cutting" in the different species of parsley is among the most elaborate of all ; but it would be difficult indeed to attempt to say which is the most beautiful in form. The wild geraniums are as elaborated as the paraleys. In some foreign plants the leaf has the brilliant hue commonly enjoyed only by flowers, the poinsettias showing this in perfection with their pure vermilion leaves at the top of the stem. In what are known to gardeners as " foliage plants," mainly from the tropical and sub-tropical regions, a scheme of colour is given as a rule, by the contrast in tint of the ribs and veins of the leaves with the tissues filling in the network so formed. Milky white, bright yellow, crimson, or red usually marks the framework of the leaf, while the "filling" is dark green. In other plants this scheme of ornament, is reversed.
Scents and perfumes, not less delicious than those distilled from flowers and blossoms, are often given out by leaves.
There are those who profess to detect a purer and more delicate odour in these leaf-scents than in the perfume of flowers ; and though this is a matter of personal taste and sensation, there is some reason to agree with this refine- ment of the sense of smell. The odour of the lemon plant, or of the leaves of musk, and, above all, the perfume of the sweet-briar leaves, are among the most " clean" and refreshing in all the category of sweet scents.
It was inevitable that a theory should be thought out to account for the varied forms and outlines of leaves. That which has found favour with many is as follows. The" simple," large, " uncut " forms are said to be those which grow at a height, and lie nearest to the sun. The elaborately " cut " leaves and leaflets (such as those of ferns) are declared to belong in the main to plants of lower growth, which only enjoy the broken sunlight that struggles through the simpler foliage of the higher plants. This is ingenious ; but it hardly corresponds with fact, as the reader may discover by noting the leaves growing in any English thicket. Take, for example, the foliage hanging over the thickly overgrown bed of a brook. Above will be the leaves (quite small) of the white- thorn and of the maple, the latter being the larger. Below these very possibly will be seen growing the large.leaved wild guelder-rose, the laurel, and the bramble, and below these again the dock leaf, the broad butter-burr, and the arum.
In English woods and thickets it would be difficult to lay down any rule which would hold good generally for the place occupied by plants with leaves of different sizes. But the theory mentioned above does fit to some extent the facts in the position of grasses in a hayfield. There the smaller- leaved species certainly do grow at the bottom, where the tiny meadow vetchlings, and hop clovers, and ladies' fingers, and other minor and sweet-scented plants, of which the best hay is made, hide their minute and finely " cut" leaves among the bases of the taller grasses. Leaves which are not symmetrical always attract attention, as something out of the common, like a " left-handed " spiral shell or a four- leaved clover. Perhaps the most beautiful of these abnormal leaves are those of the various kinds of begonia. These look
as if they had been intended to be heart-shaped, but had been altered by artistic caprice, so that one side predominates in the scale of proportion, while the other has dwindled. Yet, though the stem of the leaf of the begonia is attached on one side, and the crimson " ribs " do not radiate evenly, it will be found that if two of the leaves are placed side by side, but in
That beautiful and poisonous plant, the henbane, has non- symmetrical leaves which are, at the same time, highly decorative. Even leaves which are symmetrical, but of unusual shapes, at once attract attention, as, for example, those of the tulip tree, which are unlike those of any other plant commonly found in this country.
No one who walks abroad in the early morning at this time of the year after a misty night can fail to notice the distilling power of leaves, even when dead and fallen. Though the earth be dry and dusty, every leaf is thick with beads of dew, or wetted and soaked as if it had lain in water. Thus, after they have fed the parent tree with the extract of ether and sunlight while living, the dead leaves help to moisten the thirsty earth before their final return to dust.
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