58 BULLETIN 428, IJ. S. DEPARTMEi^T OF AGRICULTURE. 



With the Grimm variety as an example of what may be accom- 

 plished through the aid of the southern forms of Medicago falcata^ 

 even better results may be expected from the crossing of good north- 

 ern forms with Medicago sativa. Some very promising hybrids 

 have already been made between the Peruvian and Arabian alfalfas 

 and a fairly erect type of Medicago falcata similar to the form illus- 

 trated in figure 17. These hybrids combine valuable characters, in- 

 cluding to a rather remarkable degree the quick recovery and growth 

 of the Peruvian and Arabian varieties and the low croAvn and abun- 

 dant tillering of Medicago falcata. Furthermore, they have proved 

 to be reasonably hardy at Highmore. The advantages of such hy- 

 brids can readily be appreciated. 



The proliferating root character, as found in certain forms of 

 Medicago falcata., has only recently been observed in this country. 

 By the use of this character, high-yielding strains may be originated 

 that will be especially resistant to severe climatic conditions and 

 actually aggressive on soils of fairly loose texture. 



The above are only a few of the possibilities that are offered to the 

 plant breeder by this diverse species, and those who fail to see beyond 

 its agronomic defects as it exists in its natural state are missing an 

 opportunity in the field of plant breeding. 



AETIFICIAL AND NATURAL HYBRIDIZATION. 



There are two ways of utilizing Medicago falcata in the develop- ' 

 ment of hybrid strains of alfalfa ; namely, in the making of natural 

 and of artificial hybrids. The latter is the more definite and promis- 

 ing method, but the former unquestionably offers possibilities. In the 

 making of artificial hybrids both parents may be carefully chosen 

 and rigid selection made in the progeny. While the expense incident 

 to this method is considerable, satisfactory results can be secured 

 from it in a much shorter time than from the latter method. Polli- 

 nation by artificial means is easily accomplished, either by what is 

 termed the depollination method or by tripping the flower of the 

 plant selected for the female parent on a knife blade or similar instru- 

 ment upon which pollen from another plant has been collected. On 

 account of its comparative simplicity the latter method is generally 

 preferred. It appears to be true that the pollen of Medicago falcata 

 is prepotent over that of Medicago sativa on the stigmas of the latter, 

 and vice versa. At any rate, there is very little difficulty in effecting 

 reciprocal crosses between the two species. Methods of pollination 

 have been fully discussed in bulletins of the Department of Agricul- 

 ture {If-G) and other institutions. 



The fact that the hybridization which has produced the variegated 

 commercial strains of alfalfa has been the result of natural agencies 

 leads to the belief that with careful work still better results may 



