24 BULLETIN 1087, U. S. DEPARTMENT OF AGRICULTURE. 
SUMMARY. 
Factors tending to produce modifications of taproots in alfalfa 
are soil, climate, cultural treatment, and injuries. 
{Studies made at Redfield, S. Dak., were on varieties seeded at the 
same time and grown under the same soil and moisture conditions. 
Even with the greatest care, however, it is difficult to make allow- 
ances for differences in root growth of the various varieties, owing 
to the nonuniform thinning of the stand by severe climatic condi- 
tions or other causes. 
The varieties and strains studied include Peruvian, Poona, south- 
ern-grown common, northern-grown common, Turkestan, Grimm, 
and yellow flowered. The root systems of the Peruvian and Poona 
alfalfas of one season's growth are quite similar. They are charac- 
Fig. 18. 
-Root systems of decumbent yellow-flowered alfalfa plants, the growth of six 
seasons. 
terized by small, upright crowns, distinct taproots, comparatively 
few branch roots, and few fibrous roots, which are distributed rather 
uniformly over the root system. They differ in that the Poona sel- 
dom has branch roots on the upper portion of the taproot. 
For convenience, the common alfalfas are divided into two classes. 
the southern-grown common and the northern-grown common. All 
these alfalfas have distinct taproots and in general show consider- 
able similarity. The northern-grown strains have somewhat broader 
crowns and they exhibit more of a tendency to throw out branch 
roots and fibrous roots, but these differences are not sufficiently 
marked to constitute conspicuous characteristics. Both exceed the 
Poona and Peruvian alfalfas in branch and fibrous root develop- 
ment. There is practically no difference in the diameter of the tap- 
root. 
