280 



FIELD CROP PRODUCTION 



The roots are able to penetrate rather impervious sub- 

 soils, but usually grow deeper in those of a loose, open 

 character. The usual depth of the root system is from 

 3 to 12 feet. 



282. The stems of the alfalfa 

 plant, which bear short, leafy 

 branches, arise from the crown or 

 woody top of the tap root. The 

 stems may be given off a little 

 below the surface of the ground, 

 thus forming a branched crown. 

 The number of stems per plant 

 varies from 3 to 15, and in rare 

 cases individual plants may pro- 

 duce over 100 stems. The plants 

 vary in height, the average height 

 probably being from 1| to 3 feet. 



The leaves are smaller and rather 

 more narrow and more pointed 

 than those of red clover. They 

 differ from those of the clovers, too, 

 in that the three leaflets, which are 

 arranged together as in the clovers, 

 do not all grow out from the end of 

 the leaf branch in alfalfa, but the 

 two lateral leaves of the group grow out oppositely from a 

 point some little distance down the stem. 



The flowers are purple, and are carried in elongated 

 clusters or racemes, which grow out from various points 

 on the stems and branches. The flowers are similar in 

 shape to those of red clover, and both honey bees and 

 bumblebees are agents in their pollination. The seeds 

 are produced in spirally twisted pods, which may have 



Fig. 101. — Alfalfa roots. 



