MEDICAGO FALCATA, A YELLOW-FLOWERED ALFALFA. 59 
be obtained. In sections where climatic conditions. are reasonably 
favorable for seed production, hybrid strains could soon be developed 
by establishing a few plants of Medicago falcata in a field of Medi- 
cago sativa or in the fence rows and margins of the fields. A hetero- 
geneous collection of hybrids would develop from this method, but 
with the assistance of natural eliminating agencies appreciable good 
would result, especially in sections where drought and winterkilling 
are important factors. 
DIFFICULTIES IN ESTABLISHING NEW STRAINS. 
The difficulties in establishing a new variety or strain of alfalfa 
must not be underestimated. ‘There are three important factors that 
seriously interfere with the maintenance of pure strains of this crop; 
namely, the open fertilization of the flowers, the lack of distinct 
varietal differences in seed and other botanical characters, and the 
mixing of the seed either as the result of careless or unscrupulous 
handling. With regard to the first-mentioned handicap it has been 
suggested that only one variety of alfalfa be grown in a community, 
and in this way the chances for the contamination of the strain 
through the medium of cross-fertilization with other strains would 
. be reduced to a minimum. Under present conditions, this plan is 
_ not feasible, since it would be difficult, if not quite impossible, to get 
farmers to organize properly for such a purpose. 
A wide difference of opinion exists as to the effect on the characters 
of a given strain of the cross-fertilization that takes place in alfalfa 
under average field conditions. Brand (13) offers it as an expla- 
nation for the failure of a certain lot of Grimm alfalfa to survive 
the winter to the same degree as other lots of this variety tested 
with it, even though it had been directly exposed to cross-pollina- 
tion for only one seed generation. Oliver? is likewise of the opinion 
that the cross-pollination that normally takes place in alfalfa is a 
serious detriment to the establishment of superior strains, and he 
cites the case of Peruvian alfalfa in the Southwest in this connection. 
Field observations, however, do not seem to justify the belief that the 
Peruvian variety will soon lose its identity through cross-fertiliza- 
tion in the Southwest. In fact, there is no appreciable evidence that 
deterioration has occurred from this cause. That strains of alfalfa 
will lose their distinct characteristics as the result of continued cross- 
ing with other strains can scarcely be questioned, some strains per- 
haps being more susceptible than others. It also appears to be true 
that it is a mistake to attempt to breed alfalfa along narrow lines. 
Taking everything into consideration, it is safe to conclude that the 
first of the three factors mentioned is the least important. 
1Jn an unpublished paper. 
