ALFALFA ROOT STUDIES. 



23 



Decumbent yellow -flowered alfalfa.^ — The decumbent form of yel- 

 low-flowered alfalfa is intermediate between the two forms previously 

 considered. The type is represented by S. P. I No. 33465. The tap- 

 roots are indistinct, short and rapidly tapering and slightly smaller 

 than the southern-grown common and Grimm varieties, as is shown 

 in Table 5. This strain has the most extensive root system of all the 

 alfalfas studied. The rhizome development is greater than any of 

 the alfalfas except the prostrate yellow-flowered. Fibrous roots are 

 relatively abundant. (Table 7, Figs. 9 and 18.) 



Fig. 17. — Root systems of prostrate yellow-flowered alfalfa plants having distinct tap- 

 roots, the growth of six seasons. 



JKoot proliferation has been observed in Medicago falcata intro- 

 ductions from Orenburg, Eussia, and Semipalatinsk, Siberia. This, 

 characteristic has also been observed in some hybrid alfalfas. True 

 lateral roots have been found extending parallel to the surface for 

 36 inches, at a depth of 4 to 12 inches. At irregular intervals the root 

 enlarges to about double its normal diameter. These enlargements 

 or swellings send out aerial shoots and may or may not develop fibrous 

 roots. (Fig. 19.) 



S. p. I. ]sio. 33465 (Medicago falcata), from Semipalatinsk, Siberia ; presented by G. T. 

 Miroshnikoff, at the request of Frank N. Meyer. Received Feb. 19, 1912. 



