ALFALFA ROOT STUDIES. 19 



Cn plants of four season's growtli the diameter of the taproot of 

 Turkestan alfalfa is slightly greater than that of the Grimm. Branch 

 •cots are abundant and prominent, occurring in greatest profusion at 

 [| to 4:1 inches below the crown. The average angle of divergence 

 s greater than in any of the alfalfas studied except that of Medicago 

 ^alcata. Fibrous roots are very abundant and most numerous within 

 > inches of the surface. Well-developed rooting rhizomes are com- 

 non. The Turkestan alfalfa differs from the nonhardy varieties in 

 )ossessing decidedly larger numbers of branch roots and fibrous 

 ■oots; but, as shown by the data presented in Tables 5, 6, and 7, the 

 lifferences in the more pronounced root characters between this 

 '^ariety and Grimm are not sufficient to distinguish one from the 

 tther. 



GRIMM ALFALFA. 



Grimm alfalfa is the best-known variety of variegated al- 

 alfa in the United States. It is a cross between Medioago falcata 

 jnd Medicago sativa and was brought to Minnesota from Germany in 

 '858. It has been grown under rather severe conditions since that 

 lime, and as a result only the most hardy plants have survived. The 

 lants studied at Eedfield were of stock that had proved hardy and 

 roductive.* The root systems showed greater irregularity than 

 ther varieties studied, probably owing to the fact that this alfalfa 

 3 a hybrid. 



In order to observe root development in considerable detail, a 

 rench several feet in depth was dug along one of the nursery rows, 

 lany of the taproots were found to divide, some near the surface 

 nd others at considerable depths. The branch roots diverged from 

 lie taproot at angles varying from 50° to 80° for about 12 inches, 



hen most of them turned vertically downward, being only slightly 

 effected by a compact soil stratum at a depth of 3 to 4 feet.^ At 

 ais point more than the normal amount of branching occurred. As 

 ;ie next 12 inches of soil was somewhat more friable, the , roots 

 5emed to experience no difficulty in penetrating it. Small channels 

 ccurred throughout the soil which contained either partially clecom- 

 osed roots or showed evidence of having been root passages. Branch 

 Dots, although most abundant near the surface, were found all along 

 ae taproot. Small fibrous roots occurred over the entire root sys- 

 3m, being especially numerous within 5 or 6 inches of the crown. 

 a a few instances the fibrous roots were traced to a depth of 9 feet 



inches, where they terminated in a rather dry clay stratum. The 



*This seed (S. P. I. No. 29988) was harvested from a field 40 years old in Carver 

 mnty, Minn. It was purchased by the Department of Agriculture from A. B. Lyman, of 

 KCelsior, Minn., in February, 1911. 

 ^ Compare with data in Table 3. 



