.ALFALFA 



279 



introduced from South America into California, where it 

 soon met with great favor. From CaUfornia it rapidly- 

 spread eastward until a few years ago, it again reached the 

 Atlantic Coast States, coming this time from the West. 



281. Description. — Alfalfa, Medicago sativa, is a peren- 

 nial plant with an upright manner of growth and a deep 

 root system. One of the distinctive features of alfalfa 

 is the extent of its root system, which is characterized by 

 a strong, deep-growing 

 tap root, with compara- 

 tively few feeding roots 

 near the surface of the 

 ground. Ordinarily 

 the tap root does not 

 branch, but sometimes 

 two or three or more 

 strong branches, often 

 as large as the tap 

 root itself, are given off from it a few inches below the 

 surface of the ground, and they grow downward almost, 

 if not quite, as deep as does the tap root. Wonderful 

 tales have been told about the depth to which alfalfa 

 roots will extend into the ground. One account relates 

 the finding of them while digging a tunnel over one hun- 

 dred feet below the surface of the ground, and many in- 

 cidents are known where they have penetrated the ground 

 to a depth of more than twenty feet. Alfalfa is a native 

 of dry lands, and many years ago developed a deep-rooted 

 character to secure a supply of water from the moisture 

 in the deep subsoil. The roots of alfalfa will not grow 

 more than a few inches below the water table, and the 

 depth to which the roots may penetrate the soil, there- 

 fore, may be determined by the position of the water table. 



Fig. 100. — Arrangement of leaflets 

 alfalfa and clover. 



