24 AGRICULTURAL VARIETIES OF THE COWPEA, ETC. 



some varieties, however, it is practically straight and in a very few 

 coiled into one or even two complete turns. (See Xos. 21296A and 

 29278 in PL VII.) 



In most varieties of cowpeas the pod is more or less torulose ; that 

 is, constricted between the seeds. In others, however, the pods are 

 terete, not at all torulose. The color of the mature pods is drab in a 

 comparatively few varieties, straw yellow in most. In the latter case 

 the yellow may be more or less tinged with purple, a few varieties 

 having uniformly purple pods. In such cases the purple coloration 

 is usually evident in the immature pods also. In at least one variety, 

 No. 25786, the pod is yellowish with short, linear, purple splotches. 



Most varieties of cowpeas do not shatter their seeds at all. Some, 

 however, dehisce much more easily than others, this character being 

 usually associated with thin pod valves, which sometimes become 

 coiled after separating. In a few of the catjangs the pods shatter 

 much like vetches, the valves coiling immediately into a close spiral. 

 The most marked example of this is No. 2 1505 A. (PI. VI.) 



LIFE PERIOD. 



There is a wide variation in the time required for different kinds 

 of cowpeas to mature. Furthermore, accurate comparisons are diffi- 

 cult, because the period of fruiting extends over a considerable length 

 of time, which varies according to the season. Perhaps the safest 

 basis of comparison is the riperfing of the first pod, which is usually 

 about 10 to 15 days before most of the pods ripen. The earliest 

 cowpea known to us is Xo. 29282, which ripens its first pods at Arling- 

 ton Farm in 65 days. Varieties called early usually require 80 days 

 or more. Whippoorwill matures its first pods in 82 days. The latest 

 varieties that mature at Arlington Farm require 130 days, but many 

 of the lots received from tropical sources do not even bloom under 

 Arlington Farm conditions. 



The length of time between planting and the ripening of the first 

 pods also varies with the time of planting. Thus, Mooers 1 found that 

 the TVhippoorwill varied in time from planting to maturity as fol- 

 lows: Planted April 15, 183 days; May 1, 168 days; May 15, 153 

 days; June 5, 132 days; June 17, 113 days; June 29, 101 days. 



The life period also varies in some cases from season to season, not 

 only in actual period of time but in comparison with other varieties, 

 as before mentioned. 



MALFORMATIONS. 



Cowpea leaves with four or five leaflets are by no means uncom- 

 mon. The small amount of evidence available indicates that this 

 character is to some degree hereditary, probably comparable in this 



1 Bulletin 82, Tennessee Agricultural Experiment Station. 



229 



