MEADOW PLANTS 51 



the legumes have the power to add nitrogen to the soil 

 by means of the root nodules and the nitrogen-fixing 

 organisms contained therein. The choice of the legume ^ 

 for this purpose depends largely upon the secondary uses 

 that can be made of the crop. It may be made into hay 

 or may be cut green and used for soiling or for silage 

 (Par. 76). In the timothy region, clover is a staple crop 

 (Par. 46). In the South, where no perennial legume is 

 adapted to the conditions prevailing over most of the 

 region, annual legumes are used. It is true that alfalfa 

 is grown with success in many parts of the South, such as 

 the alluvial valleys of the Mississippi and Red Rivers, and 

 the black soil of central Alabama, but even here an annual 

 crop may be desired for the other purposes mentioned 

 above. The commonest of the annual legumes in the 

 South are the cowpea and velvet bean. In the North, 

 the field pea is much used, and in middle regions vetch 

 and crimson clover. 



64. The cowpea (Vigna sinensis (Torner) Savi.) is a 

 trailing vine with trifoliate leaves and slender, bean-like 

 pods. Some varieties are bushy and trail only slightly.' 

 The cowpea is the standard legume for the South. Its use r 

 has extended gradually northward until some varieties 

 are now grown as far as Michigan. It is a warm-weather 

 species and cannot be sown until the season is well 

 advanced. In the South this limitation presents little 

 difficulty, but in the North only quick-growing and more 

 hardy varieties can be used. The hay from cowpea is 

 excellent in quality, but, like all succulent forage, requires ' 

 special care in harvesting and curing. It should be 

 remembered that the feeding value of a legume like the 

 cowpea is much greater than its fertilizing value. Hence 

 the dual use of the crop, the greater part of the vines 



