APRIL LEAVES
By Julia McNair Wright
FOLIAGE is the most prominent feature of the plant world. Trunks and branches are large and grand, the parti-colored flowers are, at first glance, more beautiful, but the leaf is the most conspicuous part of the vegetation. If flowers and leaves, and wherever is now a leaf we should have a blossom, the eyes would soon tire of the glare of vivid color, and we should long for the soft, restful green of leaves.
Early in April we find the leaf buds unfolding upon the sides of the stems, or pushing up through the ground. Some of these buds are placed opposite to each other upon the stem, others are set alternately, others spirally, so that if you follow with a thread the placing of a certain number of buds you will see that the thread has made a complete circuit of the stem, and then another. Where the leaves are in a spiral placement it is merely a whorl drawn out; where there is a whorl it is merely a compressed spiral.
Let us look at a leaf blade. The woody fibre which makes up the main stem and, bound into a little bundle, composes the foot stalk, spreads out into a light, woody framework for the leaf. This framework is usually in two layers, like the nervures in a butterfly’s wing. The central line of the frame is called the mid-rib, the other parts are styled the veins. Some of these veins are coarser and stronger than others, as, for example, those which expand in the large side lobes of the maple and oak leaves; other veins are as fine as spider’s web. Every student of botany should make studies in venation, by soaking leaves until the green part has decayed, then laying them on black cloth, and brushing the pulp away gently with a fine brush, when perfect specimens of framework will remain. It is this framework which gives the form to the leaf.
Leaves were not created for beauty, but for use. Animals and plants alike are indebted to the shade of foliage for much comfort, and for some further possibilities of life and growth. You suggest, as another use, the supply of food. Yes, the grasses and many herbage plants are greedily browsed by animals; thus we owe to them indirectly our food supply.
Yet we have not reached the most important function of the leaf. To the plant itself the leaf serves as a food purveyor, gathering perhaps the larger portion of plant food from air and moisture by absorption. The leaf is also the main breathing apparatus of the plant; the leaf spreads out to air and sunlight the food received by the entire plant, and thus secures chemical changes in it similar to assimilation and digestion. The leaf makes possible the circulation of the sap. Thus the leaf serves the plant as throat, lungs, and stomach. What the human being would be without such organs the plant would be without the leaf, or some part modified, as in the cactus family, to serve the purposes of the leaf.
So, when in April, we see the trees on all sides bursting forth in verdant foliage, let us remember the manifold purposes of the leaf.