CONCERNING CLOVER. 83 



vores. 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 fer- 

 tilization upon a smaller class of insects than Dutch or purple clover. 

 But after the blossoms are fertilized, they turn down in the same man- 

 ner as in Dutch clover, only far more markedly, giving the head a con- 

 siderable 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 ap- 

 pearance to the head. Simple as is this device, it nevertheless effectu- 

 ally 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 pre- 

 venting 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 past- 

 ures 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 cal- 

 yxes of undeveloped blossoms, completing the head. After flowering, 

 the stalks lengthen and bend down to the ground, carrying the fertil- 

 ized 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 consid- 

 ered as the high-water mark of ingenuity and foresight in the uncon- 

 scious 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 



