494 FORAGE PLANTS AND THEIR CULTURE 



it is a splendid restorative crop, which has led to its 

 being largely used purely for green manure. 



603. Varietal distinctions. The varieties of cowpea 

 are very numerous. They are distinguished by various 

 characters, those of agronomic importance being the 

 habit, life-period, disease resistance and differences of 

 pods and seeds. 



On the pod and seed characters, three subspecies have 

 been recognized, namely, the catjang, with small erect 

 pods and small subcylindric seeds ; the asparagus bean, 

 with very long inflated pods which in ripening collapse 

 about the kidney-shaped seeds ; and the cowpea, with 

 pendent thick-walled pods which preserve their form, and 

 containing variously shaped seeds. 



In habit the unsupported plant may be prostrate, lying 

 flat on the ground ; procumbent, the mass two to four times 

 as broad as high ; low, half-bushy, the mass of vines once 

 or twice as broad as high ; tall, half -bushy, the mass taller 

 than broad ; erect, not at all vining and taller than broad. 

 From a forage standpoint, the half-bushy varieties are 

 most valuable, and when planted in corn or other support- 

 ing crop their vining habit asserts itself. 



604. Life period. The life period of the different 

 varieties that is, the time from germination till the 

 plant is mature is a matter of importance, especially 

 toward the northern limit of the crop. The cowpea is 

 indeterminate in growth that is, under favorable condi- 

 tions of moisture and temperature, it continues to grow 

 indefinitely and the conditions which favor excessive 

 vegetative growth inhibit the formation of pods and seeds. 

 In other words, the fluctuating variation of the cowpea is 

 very great, and many writers have mistaken this for 

 hereditary variation. On this account, some arbitrary 



