20 



BULLETIX 1087, U. S. DEPARTMENT OF AGPJCULTUEE. 



area occupied by the roots of a single 3-year-old plant was estimated 

 to be 3 feet in diameter and 10 feet deep. 



Taproots of Grimm alfalfa taper more rapidly than those of less- 

 hardy strains, but just below the crown there appears to be only a 

 slight difference in the diameters -of the taproots of the different 

 varieties, as is shown in Table 5. In the number of branch roots 

 the Grimm alfalfa exceeds the southern strains, as is indicated in 

 Table 6. Grimm and Turkestan alfalfa show somewhat greater 

 angles of divergence of the branch roots than southern-grown com- 

 mon, but the variations are hardly sufficient to constitute distinguish- 

 ing characteristics. As is shown in Table 7 the Grimm alfalfa dif- 



FiG. 14. — Root systems of Grimm alfalfa plants, the growth of one season. 



fers from the less hard}' varieties by having more numerous fibrous 

 roots, which are most abundant within 5J inches of the crown. In 

 the southern-grown strains the fibrous roots are relatively sparse 

 and quite uniformly distributed over the root system. Rooting 

 rhizomes are often well developed; but, in this respect, the Grimm 

 alfalfa is not quite so marked as the yellow-flowered kind. (Figs. 

 14 and 15.) 



The root systems of Grimm alfalfa and the strain of Turkestan 

 alfalfa studied are so similar that even the closest examination will 

 not serve to distinguish between them. The chief difference is the 

 greater uniformity of the root systems in the Turkestan variety. 

 It appears possible, however, to distinguish the southern-grown 

 common alfalfa from either of these varieties by close study of the 

 root systems of a large number of plants. This can not be done 

 where only one or two are available for study. 



