Page:Popular Science Monthly Volume 28.djvu/88

80 allied to the knotted clover. It grows much taller, but has an equally forbidding type of pods; and I notice in Southern France, where it is very abundant, that the dry stalks and oblong heads of fruit are always left uncropped on bare banks and road-sides where goats and sheep have been browsing—a fact which clearly shows that even those omnivorous grazers consider it an unpalatable morsel.

To the same group, I think, but in a more developed degree, belong three or four other British species, whose protections are somewhat less easy to understand. Of these, clustered clover appears like a still higher type of rough clover. It is a slender, creeping annual, with very small, globular flower-heads, almost buried in the angles of the stem and leaves; and it has short, broad calyx-teeth, rigidly curved backward after flowering, and with hard, sharp points. This, I take it, is a protection against browsing animals. The sea clover, on the other hand, seems rather to guard against birds or insects. In the flowering state, it looks almost exactly like a small purple clover; but as the seeds ripen it assumes a very different aspect. First of all, the calyx-teeth grow out into rather broad green leaves, so that the whole head looks more like a mass of foliage than a bunch of ripening fruit. The lower tooth, especially, becomes very long and leaf-like; and it may be remarked that, as a rule, the two lower teeth in clovers differ more or less conspicuously from the upper ones, pointing apparently to some special danger of attack from below. As the pod slowly ripens, two lips grow out on either side of the calyx, and finally meet on the top of the pod, so as to hermetically seal it, leaving only a tightly closed aperture in the very middle. Thus the calyx has, as it were, a false bottom, appearing to be empty when it is not really so, and by this means deceiving would-be intruders. It must be noticed, however, that such a deceptive device would be useless against a herbivorous animal, which could crop off the entire head; it would only serve against birds or insects, which might pick out the seeds one by one. That it does effectually protect the tiny beans is certain, for in no case will you find a calyx without a pod inside it. At the same time, so thoroughly has the calyx with its outgrowth of lips usurped the place of the primitive pod-covering that the real pod is reduced to a mere papery envelope, and can only be detected as inclosing the seed by a somewhat careful dissection. In this sea clover, too, the entire head, when ripe and dry, has a very forbidding aspect, the mass looking decidedly prickly and stringy, like a teazle; and I observe that it generally remains uncropped until the calyx and seeds fall of themselves, especially in Southern Europe, where it grows very tall. Why it should be confined to the neighborhood of the sea and of a few tidal rivers, more especially to salt-marshes, it would be hard to say; probably the special danger against which it defends itself is one found only under these circumstances, in which case it would there alone have any advantage over its competitors. Indeed, it must not be