Page:Popular Science Monthly Volume 28.djvu/91

Rh. At the same time, the pod is many-seeded, and the plant spreads largely as well by creeping and rooting at the joints.

That the object of the turning down after flowering is distinctly to protect the pod, as well as to save time for the bees, may be seen, I think, from the analogous instance of the pretty little yellow hop clover. This common and graceful English plant has primrose-colored flowers, and (as usual with yellow blossoms) depends mainly for fertilization upon a smaller class of insects than Dutch or purple clover. But after the blossoms are fertilized, they turn down in the same manner as in Dutch clover, only far more markedly, giving the head a considerable resemblance to the hop-cones from which the species takes its name. After being thus reflexed, the faded but persistent petals close over the pod, and the standard becomes furrowed with deep marks, which seem to me intended to give a crumpled, withered appearance to the head. Simple as is this device, it nevertheless effectually conceals the pod within a closely imbricated set of scales or shields, each one folding over the next like tiles on a house, and entirely preventing the access of birds or insects to the seeds. The lesser clover and slender clover seem to me to be successively dwarfed and degraded states of the same plant, due apparently in part to bad soil, and in part to diminished need for special protection.

Last of all we come to the most advanced and developed type of any, the subterranean clover. In general appearance this plant closely resembles Dutch clover, from which, in all probability, it is a remote descendant. But, growing, as a rule, on dry, sandy, or gravelly pastures closely nipped by sheep or other herbivores, it has acquired a very remarkable and ingenious mode of escaping their depredations. Like the other species similarly circumstanced, it grows close to the ground, in small tufts; and it bears a few rather large white flowers, two or three together in a starved-looking head. Looked at closely in this stage, a number of small central knobs may be distinguished at the end of the common flower-stalk. These knobs are really the calyxes of undeveloped blossoms, completing the head. After flowering, the stalks lengthen and bend down to the ground, carrying the fertilized pods with them. Then the minor pod-stalks bend back, and the undeveloped central flowers grow out into short, thick awls or gimlets, with five finger-like lobes at their extremity, representing the five spreading teeth of the original calyx. These awls next begin digging their way into the earth by a slow, gyrating motion, and at last wear out a hole in which they bury the pod and bean entire. Thus the plant actually sows and manures its own seed, and so escapes all danger from the grazing animals. This extraordinary action may be considered as the high-water mark of ingenuity and foresight in the unconscious outcomes of natural selection among the clover kind.

In conclusion, it may be added that many of these clovers are very difficult to discriminate from one another in the flowering stage; it is