Northern Prairie Wildlife Research Center
All but extreme northeastern North Dakota is home to the Missouri milk-vetch. The plant obviously gets its name from the river, not the state, for the species grows on dry plains and river bluffs from Alberta to Texas. However, plants can be found along the Missouri as far east as northeastern Iowa.
Missouri milk-vetch is a many-stemmed perennial from a heavy-crowned taproot. Outer stems may bend toward the ground. Overall height is about six to eight inches. Each silvery-hairy leaf has eleven-to-twenty one leaflets arranged along a midrib. Numerous inch-long clusters of dark blue flowers, in contrast with the silvery foliage, make this a showy little plant. Thick, inch-long pods (legumes) dry to a light tan color.
Look for Missouri milk-vetch around hilltops in moderately grazed native pastures. The species is not among those known to cause selenium poisoning and "locoing" of livestock.
The milk-vetches are members of the bean family (Fabaceae), which contains our clovers, alfalfas, peanuts, and many other important plants. Fab means "bean" in Latin. Astragalus is an ancient Greek name of some legume, and also of the ankle-bone. Missouriensis means "of old Missouri" in botanical Latin. Missouri milk-vetch was described for science in 1818 by the English botanist/naturalist Thomas Nuttall. Nuttall visited the Mandan villages in what now is North Dakota in 1810-1811.