ALFALFA ROOT STUDIES. 19 
In plants of four season's growth the diameter of the taproot of 
Turkestan alfalfa is slightly greater than that of the Grimm. Branch 
roots are abundant and prominent, occurring in greatest profusion at 
1J to 4^ inches below the crown. The average angle of divergence 
is greater than in any of the alfalfas studied except that of Medicago 
falcata. Fibrous roots are very abundant and most numerous within 
5 inches of the surface. TVell-deA^eloped rooting rhizomes are com- 
mon. The Turkestan alfalfa differs from the nonhardy varieties in 
possessing decidedly larger numbers of branch roots and fibrous 
roots; but. as shown by the data presented in Tables 5, 6, and 7, the 
differences in the more pronounced root characters between this 
variety and Grimm are not sufficient to distinguish one from the 
other. 
GRIMM ALFALFA. 
Grimm alfalfa is the best-known variety of variegated al- 
falfa in the United States. It is a cross between Medicago falcata 
and Medicago sativa and was brought to Minnesota from Germany in 
1858. It has been grown under rather severe conditions since that 
time, and as a result only the most hardy plants have survived. The 
plants studied at Bedfield were of stock that had proved hardy and 
productive. 4 The root systems showed greater irregularity than 
other varieties studied, probably owing to the fact that this alfalfa 
is a hybrid. 
In order to observe root development in considerable detail, a 
trench several feet in depth was dug along one of the nursery rows. 
Many of the taproots were found to divide, some near the surface 
and others at considerable depths. The branch roots diverged from 
the taproot at angles varying from 50° to 80° for about 12 inches, 
when most of them turned vertically downward, being only slightly 
deflected by a compact soil stratum at a depth of 3 to 1 feet. 5 At 
this point more than the normal amount of branching occurred. As 
the next 12 inches of soil was somewhat more friable, the roots 
seemed to experience no difficulty in penetrating it. Small channels 
occurred throughout the soil which contained either partially decom- 
posed roots or showed evidence of having been root passages. Branch 
roots, although most abundant near the surface, were found all along 
the taproot. Small fibrous roots occurred over the entire root sys- 
tem, being especially numerous within 5 or 6 inches of the crown. 
In a few instances the fibrous roots were traced to a depth of 9 feet 
7 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 
County, Minn. It was purchased by the Department of Agriculture from A. B. Lyman, of 
Excelsior, Minn., in February, 1911. 
5 Compare with data in Table 3. 
