LEGUMINOS^ 449 



In spite of its relatively high water requirement, alfalfa 

 is able to withstand drought. This is due to its deep root 

 system which draws upon the water in the lower strata of soil. 



Alfalfa cannot withstand alkah, and suffers if soil drainage 

 is not good. • The plant requires hme in the soil. The soil 

 type has considerable influence upon the form of the root 

 system. A hard compact soil causes a more or less branch- 

 ing root system, while in a loose soil the tap root system is 

 typically developed. 



Uses and Production. — Alfalfa is the most important hay 

 crop in the Western States. The total number of acres in 

 alfalfa in the United States, 1909, was 4,707,146; of this 

 number, the Western States furnished 4,523,513 acres. 

 The five leading States, 1909, named in the order of their 

 alfalfa production were Kansas, Nebraska, Colorado, CaL 

 fornia and Idaho. 



MEDICAGO LUPULINA (Hop Clover, Black Medic, Yellow Trefoil) 



This plant is usually annual, sometimes perennial. The 

 stems are four-angled, pubescent, and branched at the base, 

 the branches being decumbent and spreading. The petioled 

 leaves have small obovate, oval or orbicular, denticulate or 

 crenulate leaflets. The flowers are small, yellow, in dense, 

 oblong or cyhndrical heads. The pods are black, curved, 

 strongly veined, and one-seeded. 



The plant is a native of Eurasia. It is now found through- 

 out the greater part of the United States and other temperate 

 regions where it occurs in fields and waste places. It is 

 sometimes planted on poor soil, and has some promise as 

 a green manure. 



MEDICAGO AKABICA (Spotted Bur Clover) 

 This is a smooth annual plant with procumbent stems. 

 The leaflets have a dark purple spot in the center. The pods 



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