8o THE POPULAR SCIENCE MONTHLY. 



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, be- 

 long three or four other British species, whose protections are some- 

 what 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 appar- 

 ently 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 her- 

 bivorous 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 look- 

 ing decidedly prickly and stringy, like a teazle ; and I observe that it 

 generally remains uncropped until the calyx and seeds fall of them- 

 selves, 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 ; prob- 

 ably 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 sup- 



