124 THE FORAGE AND FIBER CROPS IN AMERICA 



the end of the stem or branch, a raceme ; or may spring from 

 the end of the stem or branch in a whorl, an umbel; or may 

 be arranged along the stem or branch in a head-like cluster, 

 a capitulum. In some species the flowers of the umbel or head 

 turn downward, reftexcd, as the seeds mature. 



The anterior tooth of the calyx, the one next the keel of 

 the corolla, varies in length when compared with the other 

 teeth. This furnishes a means of identifying species. The 

 petals vary throughout nearly all the colors of the rainbow. 

 In some cases the color is quite constant within the species, 

 as in alfalfa; in other species it is extremely variable, as in 

 the sweet pea. 



The depth to which the root grows is variable. In white 

 clover the roots are comparatively shallow, while in alfalfa 

 they have been reported, on what seems to be entirely reliable 

 authority, at extraordinary depths. 1 (197) C. W. Irish 

 reports finding alfalfa roots coming through the roof of a 

 tunnel 129 feet below the surface of an old alfalfa field. 2 



131. Pollination. Unlike the flowers of many members of 

 the grass family, in which the pollen is freely distributed 

 through the air by means of the wind, the organization of the 

 flowers of the legumes is such that cross-pollination can occur 

 only by means of insects or other external agencies. That 

 pollen in some species, and, perhaps, in all species, may pollinate 

 the stigma of its own flower, seems certain. That the showy 

 flowers common to the legumes serve to attract insects which 

 visit them for nectar and pollen, and thus to bring about cross- 

 pollination, seems equally certain. Whether self-fertilization 

 or cross-fertilization most commonly occurs is a matter re- 

 quiring further investigation. 



1 J. C. Hogenson reports having found alfalfa roots at a depth of 45 feet 

 in digging a well in northern Utah. Thesis, Cornell University, p. 8. 

 2 F. D. Coburn, "The Book of Alfalfa," p. 6. 



