Northern Prairie Wildlife Research Center
A true Great Plains dweller, two-grooved milk-vetch is near the center of its range in North Dakota. The plant occurs nearly throughout our state, except for some extreme north-central and eastern counties where it perhaps will be collected in the future. Elsewhere, the plant grows from Manitoba and Saskatchewan south to New Mexico and Colorado at elevations up to 8,000 feet.
Two-grooved milk-vetch is perennial from a heavy taproot and branched rootcrown. Plants are up to two feet tall. About 8-12 pairs of pale green leaflets make up the comb-like leaves which are about 3-4 inches long. About 20-30 deep purplish-blue flowers are crowded into spikes about 2-3 inches long at the top of the plant. Pods (legumes) are smooth, with two conspicuous grooves, and hang downward to ripen.
Look for two-grooved milk-vetch during June through August on heavily or moderately grazed native prairie. Plants are also often seen along roadgrades near native pastures. This species is considered one of the most troublesome of the selenium concentrators, but fortunately animals seldom seem to eat it. Many milk-vetches are used in candies, gums, cosmetics, medicines, teas, and for treatment of fabrics, but two-grooved milk-vetch is not mentioned in this regard.
The milk-vetches are members of the large and economically important bean family (Fabaceae). Worldwide, there are about 1,500 species of Astragalus; most are found in the north temperate and arctic zones. Astragalus is an old Greek name of some leguminous plant, and also of the ankle bone. Bisulcatus means "two grooved" in botanical Latin. Two-grooved milk-vetch was first described for science in 1831 by the eminent British botanist and founder of the Journal of Botany Sir William Hooker (1785-1865).