American vetch, a smooth, trailing, or climbing perennial herb, is 

 very common in the range country of the Western States. The 

 specific name, aimericana, given to this plant at the outset of the nine- 

 teenth century by the famous Pennsylvania botanist, Gotthilf 

 Muhlenberg (1753-1815), is very apropos, for American vetch is very 

 typical of its genus and is perhaps the most widely distributed and 

 best-known native vetch. 



The range of this species extends throughout most of southern 

 Canada, from New Brunswick to British Columbia, and in the United 

 States to Virginia, Kansas, New Mexico, and California. So far as 

 the western range States are concerned, American vetch ordinarily 

 occurs in rather rich, moist, frequently clayey soils from the plains 

 and foothills up to the aspen zone, especially in open, timbered areas 

 or in grass-weed parks and meadows. 



American vetch is one of the choice forage weeds, ranking from 

 moderate to high in palatability for all classes of livestock; but 

 because of its delicacy and fragility, and the fact that all its parts 

 above ground are edible including the flowers and pods it does not 

 withstand close grazing very well, and it is one of the first plants to 

 decrease under such use. If such close grazing is permitted during 

 the period of rapid development and up to the time for seed to set, 

 the plant makes little or no regrowth from the underground root- 

 stocks, and fails to produce seeds, or to store up a reserve food supply 

 for resuming growth the next season. It may thus be gradually 

 killed out. It usually produces a considerable volume of leafage and 

 tender shoots which are readily eaten throughout the growing season 

 by all classes of livestock but particularly by sheep. American 

 vetch is commonly associated with less palatable plants, such as pea- 

 vine, geranium, smooth wild-rye, and cinquefoil and, in such mix- 

 tures, is frequently very closely cropped. 



Wooton and Standley 1 refer to this species as the "common bright 

 blue-flowered vetch of the timbered mountains everywhere in the 

 State" (New Mexico), and call attention to the great variation in 

 width of the leaflets. Flowering begins in June or July and con- 

 tinues through the following month. The seeds are produced until 

 late August or September, depending upon the locality. 



1 Wooton, E. O., and Standley, P. C. FLORA or NEW MEXICO. TJ. S. Natl. Mus., Contrib. 

 U. S. Natl. Herbarium 19, 794 pp. 1915. 





