LEGUMINOUS FORAGE CROPS . 175 



Sometimes several roots set off from the tap root near the 

 crown. These are large like the tap root and extend directly 

 downward as deeply as the tap root or nearly so. In some 

 cases the roots are two to three inches in diameter, but this 

 usually occurs where the tap root is cut off or is prevented 

 from penetrating the soil to any great depth. Roots do not 

 enter the permanent water table more than four to eight inches. 

 They do not decay nor die, but simply stop growing. On ac- 

 count of the lack of fibrous roots and the depth of the branched 

 end of the tap root a much deeper proportion of the feeding 

 surface of the roots is in the sub-soil, the character of which 

 is very important to this crop. Although desirable, it is ap- 

 parently not necessary that the sub-soil be friable. Roots will 

 penetrate a hard tenacious clay if not prevented by the occur- 

 rence of a permanent water table. 1 



Under proper field conditions root-tubercles begin to occur 

 not later than two to three months from sowing. They are 

 elongated oval, not very conspicuous, occurring on both the main 

 and the fibrous roots. According to Passerini, root-tubercles 

 are more abundant during the first season than thereafter. 2 



198. Habit of Growth Above Ground. The young seedling 

 throws up a single stem, but as it grows older other erect 

 stems arise from the crown. With older plants in the spring 

 under field conditions, 3 to 12, sometimes 20 to 30, erect stems 

 6 inches to 60 inches tall, usually 18 to 30 inches, arise from 

 the crown. Plants growing alone may have from 150 to 200 

 stems. The underground portion of these stems elongates 

 slightly and thus the crown becomes branched. On these 

 branches new stems and new roots may arise. If these branches 

 are split apart, several plants may be formed from a single 

 plant. When the crop is mown during the growing season, 



1 Colorado Sta. Bui. No. 35 (1896). 



2 Bui. Soc. Bot. Ital., 1900, pp. 16, 17. 



