328 FIELD CROPS 



ground, as in the case of the bean, the seed sphtting in half 

 and forming the two cotyledons of the young plant. 



437. Differences. While the legumes have many points 

 in common, there are numerous other respects in which they 

 xliffer. 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 climl^ing, 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 

 annual species, hke the pea and the bean, root only 2 or 3 

 feet under ordinary conditions, while the perennial species 

 reach a great depth, particularly alfalfa, which under favor- 

 able conditions may go down from 20 to 40 feet. 



438. 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 

 seeds which are important articles of food for man and for 

 animals, as peas, beans, soy beans, and cowpeas. They add 

 variety to the rotation ; and, as they are seldom attacked by 

 the same insects and diseases which trouble that other im- 

 portant family of crop plants, the grasses, they furnish an 

 excellent means of combating these pests by means of a rota- 



