LEGUMINOS^ 



461 



heat, and seed production is stimulated by adverse condi- 

 tions. The first pods may come to maturity within seventy 

 to ninety days in the so-called early varieties; on the other 

 hand, some varieties do not even come into bloom under 

 conditions prevailing in the states along the Gulf of Mexico. 



The flowers are white or 

 pale violet with three 

 bracts at the base of each 

 pedicel. The cowpea 

 flower is capable of self- 

 fertilization, and this is 

 probably the most com- 

 mon occurrence although 

 the flowers are often visited 

 by honey bees or bumble- 

 bees. They are attracted 

 chiefly by the extra-floral 

 nectaries. The long pods 

 (Fig. 194) are cylindrical, 

 somewhat curved, and 

 usually constricted be- 

 tween the seeds. The 

 seeds are numerous, usu- 

 ally bean-shaped, spotted, 

 marbled, speckled, or mar- 

 bled and speckled, and 

 have a dark circle around 

 the white hilum. Great 

 variation occurs in pods and seeds. There are two groups 

 of cowpeas based upon pod and seed characteristics; kidney 

 and crowder. The former have compressed pods with kidney- 

 shaped seeds; the latter have thick-walled, cylindrical pods 

 with globular seeds. 



Fig. 195. — Cowpea (Vigna sinensis). 

 (After Piper.) 



