[CLIMBING PLANTS.]
BY MRS. S. B. HERRICK.
Fig. 1.—The Bean. First Leaves in different Stages.
Have you never wondered, when you looked at a tangle of grape-vine or morning-glory stems, how they came to twist themselves together so? Perhaps you had some sort of a notion that they got tangled up as a bunch of silk or a skein of worsted lying loose might do. Examine any vine which you can find growing near you, and see how different the tangle is from a snarl of thread, there is a regular twist, the branches coiling in the same direction. In some plants the turn is from right to left, in others from left to right.
There must, of course, be some reason for this, and we can best find it out by taking a young plant, a seedling, and watching what it does from the start.
It would be very natural to think that plants moved only as stones do, because something pulled or pushed them; but this would not be a true conclusion. Every plant that we know much about is firmly fastened by its root in the ground; the movements of its leaves and flowers seem only caused by the blowing of the wind or the beating of the rain. But though plants are anchored fast to the earth, they are all the while moving as they grow.
Fig. 2.—Movement of Root of Black Bean.
A, Position at nine o'clock.
B, Position half an hour later.
Take some seed—beans will do—and after soaking them, plant them in the ground about two inches deep. In a week or ten days you will see the earth cracked all about. This is not because the growing plant acts like a wedge and splits the earth open, but because in growing the first little leaves move round and round, boring their way out of the ground very much as a corkscrew works its way into a cork. The first leaves of most plants—a bean, for instance—do not come straight up out of the seed; but when the seed coat bursts from the swelling of the inner part a little arch projects, which raises itself up. This arch is the stem, and after a while the leaves are pulled out of the sheath, and the arch widens out, and finally straightens up. You have often seen a man who had a heavy weight to lift bow himself over and receive the weight, and then lift it by straightening himself, as the stem does to lift the leaves (Fig. 1, first leaves). The root burrows into the earth in very much the same way as the stem revolves, by going around and around as it grows (Fig. 2). Take a morning-glory vine, and let it lie without any wire or trellis to catch hold of. After a while you will find the stems and tendrils coiled round each other in a tight twist (Fig. 3); you could not begin to twist them so tightly yourself without breaking the stem.