. MEDICAGO FALCATA, A YELLOW-FLOWERED ALFALFA. 39 
cago falcata and Medicago sativa in this instance may have been due 
to these conditions, particularly to the dryness of the soil. 
The various forms of Medicago falcata exhibit shght differences in 
the earliness of spring growth. It seems to be true that young plants 
_ of all alfalfas start growth earlier than old plants. Therefore, only 
plants of the same age should be compared in making observations on 
this point. 
In his discussion of Peruvian alfalfa, which he describes as Medi- 
cago sativa variety polia, Brand (12) calls attention to the ability 
of this strain to continue growth during the late fall and winter 
when other varieties of A/edicago sativa become dormant on account 
of the low temperature. The term “zero point” is applied by him 
to the minimum temperature at which growth can be made. He 
consequently classes Peruvian alfalfa as a variety which has a low 
zero point and common alfalfa as a variety with a comparatively 
high zero point. Brand’s observations were made in southern Ari- 
zona, and had Medicago falcata been studied in comparison with the 
varieties of Medicago satiwa it doubtless would have been considered 
as having the highest zero point of all, since it discontinues growth 
in the Southwest earlier than any of the other varieties of alfalfa. 
A study of the various alfalfas at different latitudes with regard 
to their phenological characteristics reveals some rather interesting 
and important points. The most important of all, perhaps, is the 
effect of severely low temperatures on their so-called zero points of 
growth. This can be explained best by citing the behavior of the 
distinct forms in different parts of the country. In California and 
the far Southwest, McKee finds it readily possible to distinguish 
Peruvian alfalfa, common alfalfa, I/edicago sativa & falcata hybrids 
(the general group of variegated alfalfas), and Medicago falcata by 
their growth in late fall and early spring, without regard to their 
morphological characters. They discontinue growth in the fall and 
resume it in the spring in the order in which they are named above. 
The same order obtains in general at the Arlington Farm, Va., with 
some seasonal variation, but at Brookings and Highmore there is a 
tendency toward the reversal of this order. The latitude of Wash- 
ington, D. C., appears to be about the dividing line, if high altitudes 
are excepted. : 
SPRING GROWTH. 
Westgate (66) in discussing Medicago falcata X sativa hybrids 
says, “in earliness of starting in spring as well as in earliness in 
blooming, the variegated alfalfas appear to exceed the ordinary 
kinds.” He qualifies this statement somewhat by saying “In the 
southern one-half of the United States the variegated alfalfas are 
