8 
Colorado Experiment Station 
With this object in view, a number of individual plant selections 
were made. 
After the variety test had passed the second winter, it became : 
very evident that there were non-hardy strains of alfalfa in the i 
test. This was evidenced by heavy winter killing in certain of the i 
plants. The proportion of loss seemed to be correlated with the > 
region from which the variety came. The extreme southern varieties j! 
were almost completely winter killed. The extreme northern varie- J 
ties practically escaped winter loss. Further investigations revealed | 
a relationship between the type of plant and its ability to with- ■ 
stand winter injury. 
It was found that the plants with an upright growing type of ; 
crown, where the stems started out near the surface of the ground, | 
were the plants which suffered most from winter killing. In this ' 
type of crown, the buds for the next season’s growth were more or : 
less exposed to freezing and thawing and drying out. At any rate, , 
the type of plants with the exposed crown suffered winter losses | 
much more extensively than the type having a more deeply sub- 
merged crown. 
On the other hand, the alfalfa plants which had a heavy stooling | 
habit with a spreading crown, the buds of which largely started | 
beneath the surface of the soil, suffered much less from winter kill- 
ing. Evidently there is a difference in plant resistance in these two ; 
types of alfalfa. But the fact that the buds of the erect type are 
more exposed to freezing and thawing than the buds of the heavy 
stooling type may have something to do with winter resistance. The I 
northern or heavy stooling types have their buds protected by a | 
considerable layer of soil. Hence, freezing and thawing and drying ! 
out are reduced in effect. It is probable, therefore, that a part of the i 
hardiness is due to inherited qualities and a part to protection, due i 
to the habit of growth. i 
The conclusions of these observations were ’published in 1911 | 
in the Colorado Experiment Station bulletin No. 184, ‘‘Alfalfa, The 
Relation of Type to Hardiness.” ! 
It thus became evident that any system of seed selection to im- 
prove alfalfa must take into consideration the question of hardiness I 
and desirable forage production, as well as good seed production. 
With this in view, a long series of individual plant selections of 
special merit have been made during the past ten years. | 
Over 400 specially good plants have been saved separately and \i 
tested for comparative values. Their progenies have been reselected i 
for several generations, where the results seemed to warrant. 
