14 BULLETIN 428, U. S. DEPARTMEKT OF AGRICULTURE. 



COMPOSITE DETAILED DESCRIPTION. 



The flowers of the numerous forms of the species vary consider- 

 ably in color, size, and shape of banner, length of calyx teeth, and 

 slightly in length of calyx tubes. There is also a variation in the 

 length of pedicels, the number and compactness of the racemes, the 

 number of flowers in the raceme, and the date of blooming. In 

 color the flowers range from a light yellow to a deep chrome yellow, 

 the pale yellow color being the most prevalent in the individuals that 

 more nearly approach Medicago sativa in general appearance. 



On the steppes of northern Eussia and Siberia occur forms that 

 have variegated flowers. These forms are found apparently remote 

 from forms of Medicago sativa and so closely associated with forms 

 of Medicago falcata, having pure yellow flowers that Prof. Dilit- 

 winoff,^ of the Academy of Sciences, Petrograd, is of the opinion 

 that they are true forms of the latter. Meyer, however, who has 

 studied them in their native habitat, believes them to be hybrids of 

 Medicago sativa and Medicago falcata^ and a study of the progeny 

 of these plants grown from the seed collected by the department's 

 explorers indicates quite definitely that Meyer's opinion is well 

 founded. The progeny exhibits a diversity of forms, some of which 

 closely resemble Medicago sativa, while others present the appear- 

 ance of true Medicago falcata. But regardless of this, the wild 

 variegated forms are regarded with interest in connection with the 

 study of the origin of the cultivated alfalfas and the botanical 

 relationship existing between the above species. 



Flowers. — The individual flowers of Medicago falcata are smaller 

 than those of Medicago sativa. The lines which mark the banners 

 are shorter in the former than in the latter and are light to dark 

 brown, varying directly with the color of the flower. A large num- 

 ber of careful measurements show that the banners vary from 6.25 

 to 12 mm. in length and from 2.20 to 8 mm. in width. The ratio of 

 length to width of the banner also varies, ranging from approxi- 

 mately 1.2 to 1 to 3 to 1. The calyx averages about 1.T5 mm. in length 

 and varies from approximately 1.3 to 2.6 mm. There is a greater 

 variation, however, in the length of the calyx teeth, the range being 

 from 1.25 to 3.75 mm. The pedicels are from 1.25 to 3.75 mm. in 

 length. 



There appears to be little uniformity in the number of flowers in 

 the raceme. In some cases as few as five are found, while in others as 

 many as 36 may be present. Eacemes with the largest number of 

 flowers have been noted to be compact and of medium size. The 

 very fine leaved plants and the plants with long procumbent stems 

 have small racemes, with comparatively few flowers. Likewise, the 



1 In letter on file in the United States Department of Agriculture. 



