DIFFERENCES IN LEGUMES 349 



legume, which splits open along both edges when mature. 

 The seed is almost entirely filled with the cotyledons or 

 seed leaves, and on germination the entire seed often appears 

 above ground, as in the case of the bean, the seed splitting 

 in half and forming the two cotyledons of the young plant. 



446. Differences. While the legumes have many points 

 in common, there are numerous other respects in which they 

 differ. They may be small herbs, shrubs, vines, or trees. 

 They may be annual, biennial, or perennial. The herbaceous 

 plants may be erect, as alfalfa; prostrate, as white clover; 

 trailing or climbing, as the vetches and some forms of the 

 cowpea. The leaves may be made up of three or many 

 leaflets; they may be palmate, all the leaflets growing from a 

 single point, as in the clovers; or they may be pinnate, the 

 leaflets being arranged along the midrib, as in alfalfa and the 

 vetches. The flowers may be of many sizes, forms, and 

 colors, and may be arranged in numerous forms. They may 

 be in a close umbel, or head, as in the clovers, or in a spike or 

 raceme, as in alfalfa and sweet clover. The seed pods may 

 be long and straight, as in the pea; more or less curved, as 

 in the bean; coiled, as in alfalfa; or of various other shapes 

 and sizes. Though the roots are all of the same general form, 

 consisting of a main taproot with many branches, they vary 

 greatly in the depth to which they penetrate the soil. Some 

 of the annual species, like the pea and the bean, do not root 

 deeper than 2 or 3 feet under ordinary conditions, while the 

 perennial species reach a great depth, particularly alfalfa, 

 which under favorable conditions may go down from 20 to 

 40 feet. 



447. Why the Legumes Are Important. The legumes 

 are important in our system of farming for several reasons. 

 They supply palatable forage which is especially rich in pro- 

 tein, much richer than any of the grasses. They also furnish 



