ASTRAGALUS, a very large genus of the pea family (Leguminosae or Fabaceae), widely distributed throughout the world, except in Australia, but most numerous in the steppe re gion of northern Asia, the high plains of western North America and the tropical Andes. The common species of Great Britain and of the eastern United States and Canada are called milk vetch. They are mostly low herbs though some are shrubby, with leaves usually divided into many narrow leaflets. Astragalus con tains upwards of I,600 species. More than 275 of these are found in North America, 95% of which occur west of the Mississippi river. Although in number of species Astragalus ranks among the largest of plant genera, only a few are of economic importance. Gum tragacanth is derived from A. gummi f er and other related low spiny shrubs native to Asia Minor. In Persia a sort of manna is obtained from A. florulentus. In northern Europe A. boeticus is cultivated for its seeds, which are used as a substitute for coffee, sometimes called Swedish coffee.
The long roots of A. aboriginurn, which occurs from Saskatche wan to Alaska and southward to British Columbia, Nevada and Colorado, are used for food by the Crees and other North Amer ican Indians; in the plains region of the United States, extending from Nebraska and Wyoming southward to Texas and New Mexico A. mollissimus and other related species called loco-weed are poisonous to grazing animals. Many highly ornamental old world species of Astragalus are in cultivation and several native to North America are now sparingly planted.
For North American species, see P. A. Rydberg, Flora of the Rocky Mountains and Adjacent Plains (1917), and numerous contributions in The Torrey Bulletin; M. E. Jones, Revision of North-American Species of Astragalus (1923) ; Ivar Tidestrom, Flora of Utah and Nevada (1925) ; and W. L. Jepson, Manual of the Flowering Plants of California (5925); "Locoweed Disease," U.S. D. Ag. Farmer's Bull. ; "Timber Milk Vetch," Colo. Ag. Exp. B. 425 (1936).