TWO TYPES OF PROLIFERATION IN ALFALFA. | m 
In summarizing the observations and conclusions of the various 
investigators it will be found that certain types of alfalfa, chiefly 
those which are associated with hardiness and drought resistance, 
produce underground stems and rhizomes; that these growths are 
true stems having nodes, scales, and buds; that although sometimes 
found several inches beneath the surface, they usually originate at 
or near the crown, seldom below; that the rooting and nonrooting 
rhizomes may result in new shoots and in some cases ultimately in 
independent plants; that by virtue of their ability to store up water 
and produce protected buds they constitute a drought-resistant and 
hardy character of much value to the plant; and that the rhizomes 
in their various forms are more abundantly produced in J/edicago 
falcata and its natural and artificial hybrids with J/. sativa than in 
pure J/. sativa. 
The rediscovery, if such it may be called, of stem proliferation in 
alfalfa is of vast importance, especially to plant breeders, as it gives 
them a tangible character with which to work in developing hardy 
and drought-resistant strains. 
Field studies and correlation of characters—In May, 1912, the 
writers took up a general study of proliferation in J/edicago falcata 
with a view to determining the extent of its prevalence and variation 
in the different types of that species. Although late spring is prob- 
ably not the best season of the year in which to study this character, 
the abundant material in the nurseries at Brookings and Highmore, 
S. Dak., afforded an excellent opportunity for observation, especially 
since the plants were growing in cultivated hills and most of them 
entering into their fourth season of growth.* 
A careful examination of the numerous forms of J/edicago falcata 
showed underground stems or rhizomes to be more prevalent and 
better developed in the low-spreading, fine-leaved, fine-stemmed types 
than in those more closely resembling J/. sativa. However, not all 
of the forms included in the low-spreading type exhibit tendencies 
to produce new plants vegetatively. Some spread only over the 
surface of the ground, the procumbent stems proceeding from fairly 
compact and high-set crowns without becoming attached to the soil 
at any point. It was extremely difficult in the case of certain pro- 
cumbent types to determine whether proliferation was largely the 
result of an inherent tendency of the plant or was induced to a 
considerable degree by cultivation. Cultivation unquestionably is 
im a measure responsible for rooting stems in the erect as well as 
in the procumbent forms. This point was quite definitely demon- 
1The plants were grown in the nursery at Brookings and transplanted in hills at 
Highmore in April, 1910. It is a well-known fact that the pruning incident to trans- 
planting large alfalfa plants affects the development of the taproot. The above-mentioned 
plants, however, were so small at the time of transplanting that little change in this 
respect is believed to have been produced. 
[Cir. 115] 
