CONCERNING CLOVER. 75 



variegated with convergent lines of different colors, which guide the 

 bee toward the exact spot where the nectaries are engaged in elabo- 

 rating honey for his benefit. The two next in order, called the wings, 

 are generally shorter and smaller, and in most advanced types they 

 possess two little indentations, one on each side, specially adapted to 

 afford a foothold for the legs of the visiting bee, in the exact position 

 that will enable him at once to reach the honey and to brush off the 

 pollen against the sensitive surface. The two lowest petals of all are 

 usually united by their under edge, so as to form a single organ, 

 known as the keel, and closely inclosing the stamens and pistil. As a 

 rule, too, all ten stamens are united into a single tube or sheath ; or 

 else the nine lower ones are so united, while the upper one is free. In 

 spite of the general uniformity of floral type, however, many special 

 modes of insect fertilization prevail among the various pea-flowers. 

 Sometimes the blossom bursts open elastically when the bee lights 

 upon it, dusting him all over with the ripe pollen ; sometimes a small 

 quantity is pumped out from the sharpened point of the keel by the 

 weight of the insect's body ; sometimes the pollen is dejDOsited from 

 his breast on the spirally curled summit of the pistil ; sometimes it is 

 swept off by a little brush of hairs, situated close beside the sensitive 

 surface of the embryo pod. All that it is here necessary to bear in 

 mind, however, is the general fact that the papilionaceous tyj^e of 

 flower has gained its present high position as a dominant floral pattern 

 by its beautiful and varied adaptation to insect fertilization. 



Such being the general nature of the pea-flowers as a M'hole, we 

 have next to inquire what are the special peculiarities which have en- 

 abled the clovers in particular to fill their peculiar niche in the exist- 

 ing economy of Nature. Clearly, the positions which clovers are 

 adapted to adorn are not the high places in the hierarchy of vegetal 

 life. They are not tall forest-trees or bushy shrubs ; they are not long, 

 creeping trailers or climbers ; they are herbs of low and procumbent 

 character, best fitted for filling up the interspaces of taller vegetation, 

 and for vying with the grasses as elements of the close, tender, deli- 

 cate greensward. The points which have enabled them to survive, 

 therefore, are just those which allow a plant to thrive under such spe- 

 cial conditions ; and we must ask briefly what those points may be be- 

 fore we proceed to consider the specific characteristics of the various 

 individual clovers. 



In foliage the clovers are distinguished by their graceful trefoil 

 leaves which are an adaptation of the typical papilionaceous pattern 

 to the special necessities of their humble situation. For the common 

 form of pea-leaf consists of a long leaf -stalk, with one terminal leaflet, 

 and with several pairs of lateral leaflets, arranged opposite each other 

 along a central line. In the clovers, however, and in most other small 

 field forms of papilionaceous plants, only one pair of lateral leaflets is 

 developed ; and this arrangement allows the leaf -stalk to be elevated 



