Northern Prairie Wildlife Research Center
Found throughout North Dakota, Canada milk-vetch blooms in late July. The plant can be found in many parts of Canada, in Siberia, across the eastern United States, and from Texas to Utah.
Canada milk-vetch is the largest of the 21 species of milk-vetch found in North Dakota; specimens over four feet tall have been encountered. Plants are perennial from rhizomes, so clumps of multiple stems are normally seen. Two to five dozen greenish-white to pale yellow flowers occur in dense cylindric clusters (racemes) up to 8 inches long. Each flower is about five eighths inch long. Leaves are green, up to 12 inches long, and bear up to 35 inch-long leaflets arranged pinnately. At maturity the cylindrical brown pods (legumes) are about one half inch long. Clusters of legumes remain upright all winter.
Look for Canada milk-vetch in rich native prairie at the bases of hills and slopes. This plant has sometimes been called "little rattlepod" because Amerindian children used the pod clusters for rattles. Roots harvested in the spring or fall were eaten raw or boiled. I could find no references to the effects of grazing on this species. Some astragali produce toxic alkaloids and others accumulate selenium if it is present in the soil and thus poison livestock, but Canada milk-vetch seems innocuous in this regard.
milk-vetches are members of the economically important bean family (Fabaceae). Fab means bean in Latin. The genus Astragalus (an old Greek name of some leguminous plant, also of the ankle-bone) contains some 1500 species, chiefly of the north temperate and arctic zones. Canadensis means "Canadian" in botanical Latin.
Canada milk-vetch was described for science by the Swedish father of modern plant taxonomy Carl von Linne (Linnaeus) in his monumental Species Plantarum of 1753.