CHAPTER XI 

 COWPEAS, SOYBEANS, AND VELVET BEANS 



Cowpeas, soybeans, and velvet beans belong to the group 

 of naturally self-fertilized crops. The fundamental principles 

 involved in breeding crops of this group have already been dis- 

 cussed. It suffices here to point out that the method of breeding 

 these three legumes does not differ essentially from that for the 

 group. 



COWPEAS (Vigna sinensis) 



Origin. A wild plant closely related to the cultivated cowpea 

 grows quite generally over the continent of Africa. The wild 

 form differs from the cultivated in having smaller seeds and in 

 having pod valves which coil in ripening. The two forms may 

 be hybridized with ease. This fact and the fact that wild cow- 

 peas have been found in no other place, are generally accepted as 

 evidence (Piper, 1916) that the cultivated form arose in Africa. 



Description and Inheritance. The cowpea resembles the 

 garden bean in general appearance. Some varieties grow erect 

 while others are vine-like and trail over the ground. The pods 

 are rather long and contain from 6 to 15 seeds each. Flowers 

 are white or nearly white and pale to medium violet purple and 

 are shaped like those of the garden pea. Seed coats vary a great 

 deal in color some are mottled, others uni-colored. The life 

 period of this plant is too long to permit its growth very far 

 north, and for this reason an earlier maturing cowpea is desirable. 



Size and shape of pod and seed have been used to separate the 

 larger groups. No studies of inheritance of these major differ- 

 ential characters have been made. 



Color inheritance with particular reference to the seed-coat 

 has been studied by Spillman (1911) and more recently by 

 Harland (1919a, 6, c, 1920). Anthocyanin coloration in the stem 

 and leaf stalk is dependent on a single factor difference X, 

 dominant to its absence. The inheritance of seed coat pattern 

 involves factors B (black), N (buff), M (Maroon) and R (Red), 



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