Alkali Poisonvetch
Alkali Poisonvetch, Pale Milkvetch, Cream Milkvetch
Astragalus racemosus Pursh
Fabaceae (Legume Family)
Mature plants ▼ ▲
Mature plants ▼ ▲
Mature plants ▼ ▲
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▲ flowers, leaves and forming pods
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▲ Population of alkali milkvetch in western Kansas
Pale Milkvetch (Alkali Poisonvetch) (p. 301, Weeds of the Great Plains; not in Weeds of the Northeast)
Pale Milkvetch is a midwest native plant found on alkaline, chalky soils, and in high-selenium content soils. More may be found in areas where there has been some soil disturbance or overgrazing.
The entire plant (not just flowers) has a unique, characteristic, strong musky odor (similar to two-groove milkvetch) that is evident when they are nearby. The plant tends to have an upright-ascending branching pattern, with several branches arising from a simple perennial tap root. Stems may be green or reddish, with hairy, pinnately-compound leaves with oval leaflets. They have upright racemes of showy white to pinkish-purple to rose-purple flowers in late spring to early summer, followed by slender, slightly grooved pods.
Alkali poisonvetch appears very similar to two-groove milkvetch and can be distinguished by the deeply grooved pods (in two-groove milkvetch) and different stipule and sepal characteristics. Alkali poisonvetch will tend to have white to pale-purple flowers, while two-groove milkvetch will usually have purplish or rose-purple flowers, but there is overlap in flower color for both species.
Consumption of alkali poisonvetch can cause selenium toxicity in grazing animals. This plant usually will not be grazed if more desirable vegetation is available.