Northern Prairie Wildlife Research Center
One or our most common milk-vetches, lavender milk-vetch occurs statewide. Elsewhere, the plant can be found from Manitoba to Washington southward to Nebraska and New Mexico at elevations up to 11,000 ft..
Lavender milk-vetch stands up to a foot tall from a heavy perennial taproot and rootcrown. The dozen or more stems may lie along the ground, forming clumps up to two feet wide. Numerous leaves, each comprised of nine to nineteen narrow leaflets, are about two to four inches long. The lavender to bluish-purple flowers are about one half inch long, and arranged in dense clusters that may be round and about one half inch wide, or cylindrical and about one to three inches long. Small hairy pods (legumes) form later.
Look for lavender milk-vetch in dry soils in moderately or heavily grazed native prairie. Cattle seem to mostly avoid the plant, even though it is not listed as one of the species which cause selenium poisoning or "locoing". Many astragali are used worldwide in gums, soaps, cosmetics, and medicines, but I could find no reference to such uses for lavender milk-vetch.
Milk-vetches are members of the bean family (Fabaceae) which is of great economic importance. Fab means "bean" in Latin. The generic name Astragalus is an ancient Greek name of some legume, and also of the ankle-bone. The specific epithet adsurgens means "rising up near" in botanical Latin, probably in reference to the stems, which often bend outward along the ground for a short distance before becoming erect. Lavender milk-vetch was first described for science by the early German botanist-zoologist Peter Pallas (1741-1811).