52 A TEXT-BOOK OF GRASSES 
and leaves being used for hay or green feed, the remainder 
being turned under for green manure. When grown on 
sterile soil it may be necessary to turn under a larger 
proportion in order to produce humus. (See Farmers’ 
Bulletin No. 318.) 
65. Velvet bean (Stizolobium Deeringianum Bort).— 
This coarse rank-growing vine is similar to the cowpea but 
gives a much greater growth. The velvet bean is not so 
hardy as the cowpea and is used only in the South. It 
has given excellent results in Florida. (See Farmers’ 
Bulletin No. 509, and Bur. Pl. Ind. Bulletin No. 179). 
66. The vetches are upright or reclining plants with 
tendrils at the ends of the compound leaves. In a general 
way they resemble the garden pea, but the leaflets and 
flowers are smaller. There are two common kinds of 
vetch in use in the United States—spring vetch (Vicia 
sativa L.) and hairy vetch (V. villosa Roth). The one 
most grown is the latter, since it better withstands 
drought. The vetches are usually sown with grain, the 
latter supporting the vetch, thus producing a combina- 
tion that can be harvested with greater ease than can the 
vetch alone. Vetch may be used as a winter crop in the 
South or as a summer crop in the North. (See Farmers’ 
Bulletins Nos. 515, 529.) 
67. Crimson clover (Trifolium incarnatum L.)—This 
is a tall clover with long heads of crimson flowers. It is 
rather extensively used in the region from New Jersey to 
North Carolina. It should be cut when in flower. If cut 
later the fuzzy hairs around the head prove troublesome, 
especially to horses. (See Farmers’ Bulletin No. 579.) 
Field pea (Pisum arvense L.). The field pea, resembling 
the garden pea in habit, is much used in Canada and our 
more northern states. The field pea requires a cool, 
