MEDICAGO FALCATA, A YELLOW-FLO WEEED ALFALFA. 37 



Medicago sativa^ although in a few of the erect forms there is com- 

 paratively little difference in this respect. From a similar stand of 

 the same height of mass growth Medicago faleata will produce a 

 heavier yield than Medicago sativa^ partly because of the thicker 

 growth of stems and partly because of the texture of the herbage. 

 Estimates of yields based upon appearance therefore commonly err 

 in favor of Medicago sativa. Conditions of soil and stand being 

 equal, individual cuttings of the best upright forms of Medicago 

 falcata frequently outyield those of varieties of Medicago sativa.. 

 A characteristic of considerable importance in any hay crop is the 

 proportion, b}^ weight, of leaf to stem. The plants of Medicago fal- 

 cata show great variation in this respect, making the character of 

 little value in any system of classification. However, in the very low 

 forms the proportion is greater than in the more erect ones. A crit- 

 ical study of 27 S. P. I. introductions indicates that the leaves com- 

 pose from 31.5 per cent to 67.5 per cent of the total dry weight of 

 the herbage. The highest percentage of leaves was found in group 1 

 in plants of S. P. I. Nos. 20717 and 20725. McKee {l+'B) presents data 

 on the percentage of leaves by weight for three varieties of Medicago 

 satica, as follows: 



Peruvian 52. 5 per cent. 



Arabian 56. 4 per cent. 



Common (Utah grown) 49. S per cent. 



According to the investigations of the Utah Agricultural Experi- 

 ment Station {67) the percentage of leaves by weight in common 

 alfalfa ranges from 22.7 to 38.4, depending upon the stage of matur- 

 ity. It is safe to assume that the erect forms of Medicago falcata are 

 not essentially different from the common varieties of Medicago 

 sativa with respect to the above character. The leaves of the former, 

 however, are retained after curing to a greater degree than those of 

 the latter, which is a very important factor. 



STEM CHARACTERISTICS. 



The size and numbei- of stems of the plant vary greatly with its 

 habit of growth. (Eig. 17.) In the very procumbent or prostrate 

 plants the stems usually are finer and more abundant than in the 

 more erect ones. An actual count made on plants 4 years old indi- 

 cates the number of steins to range from 292 in S. P. I. No. 20718, a 

 large uhcending form, to 1,082 in S. P. I. No. 20717, a broad-crowned 

 form. Plants of Turkestan alfalfa of the same age and grown under 

 similar conditions lind approxiinntely 225 stems per i:)lant. In this 

 agronomic diarnctcr also Medicago falcata com[)ares A'ery favorably 

 \\\i\\ Medicago sativa. 



