40 BULLETIN 428, U. S. DEPARTMENT OF AGRICULTURE. 
normally later in starting than the ordinary variety.” This indi- 
cates possibilities worth considering in the development of new agro- 
nomic strains of alfalfa through the hybridization of Medicago sativa 
and Wedicago falcata. It seems quite probable that severely low 
temperatures materially influence the ability of varieties to commence 
growth in the spring. In the colder and drier portions of the Great 
Plains area a variety of alfalfa making a growth in the early spring 
is more certain of producing a good crop of hay than those that are 
slow in starting, as it is able to take advantage of the winter moisture. 
Since one good cutting is sometimes all that can be obtained. the 
ability of a variety to produce early spring growth is of consider- 
able importance. J/edicago falcata not only possesses this charac- 
teristic, but is able to transmit it in some degree to the progeny re- 
sulting from its hybridization with Medicago sativa. 
In May. 1915, the effects of the five severe frosts and freezes which 
occurred during that month were observed on the nursery rows at 
Redfield, S. Dak. The rows of Medicago falcata showed decidedly 
less damage than the adjoining rows of Medicago sativa. It is true 
that the plants of the former, being of lower growth than those of the 
latter, may have received some protection from the earth. With the 
exception of the introductions from India, S. P. I. Nos. 26927, 29139, 
and 30433, the J/edicago falcata plants showed almost no frost effect, 
while those of edicago sativa were badly wilted. The effect of the 
frost was apparently the same on the Grimm, Canadian variegated. 
Baltic, Turkestan, and local Dakota strains. 
RECOVERY -AFTER CUTTING. 
A characteristic wherein Wedicago falcata differs materially from 
Medicago sativa is in rate of growth after cutting. The ability to 
produce several crops of hay in a season under favorable conditions 
has been largely responsible for the popularity which the latter has 
had for centuries. Unfortunately, the former does not possess this 
ability to any considerable degree; in fact. only under very favor- 
able conditions can more than one good cutting be procured from it. 
Table II indicates the comparative rate of recovery of JJedicago 
falcata and Medicago sativa after cutting at Brookings. 
Taste Il —Comparative rate of recovery of Medicago falcata and Medicago 
sativa after cutting, at Brookings, S. Dak., in 1913. 
i 
| Height of growth— 
Plants cut Jime 19. 
| 
| July s. (Tale, 
Inches. | Inches. 
Menicaro ticata, seven mtroductions.+_ 2: .< - £-- 2-2-2 se 22 ee eee ee eee 4t09 S8to13 
Meise aPO Sakiya b WO SRIAINS - 5225 oon ee ee ee 16 197020 
