XAstragalus convallarius - Lesser Rushy MilkvetchX
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Lesser Rushy Milkvetch -or- Timber Milkvetch (Astragalus convallarius), family Fabaceae (Pea/Bean)
Many thanks AGAIN to Dr. Matt Lavin, for his assistance in the identification of this species. There are four variants of convallarius: convallarius, finitimus, margaretiae, and scopulorum. Var convallarius is found in Colorado, per the USDA Plant Database. Var scopulorum is mentioned as uncommonly present in Colorado in Weber's keys of the Eastern Slope. So it is possible that this plant could be one of those two.
USES: Per the wonderful website Native American Ethnobotany, Astragalus convallarius var convallarius was used by the Gosiute tribe as a horse medicine. This is interesting in view of the known toxicity to livestock of this species. From a 1975 citation by M. C. Williams and L. F. James in the FDA Poisonous Plant Database is this: Methemoglobin analyses in sheep indicated that nitro compounds in A. diversifolius, A. convallarius, and A. pterocarpus resembled 3-nitro-1-propanol in toxicity and rate of absorption from the digestive tract. Possibly the horse medicine was applied by members of the Gosiute tribe topically?
An important diagnostic feature of Astragalus convallarius is that it has both grass-like leaves and pendent, linear, bean-shaped fruits. Most commonly the flowers are off-white to yellow in color. Note in the plant slide that the plant did show numerous flowers in pale yellow.
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Plant location: Photographed on Heeney Road 30 near Silverthorne Colorado, on July 5, 2011. GPS coordinates: N39?53.748 W106?18.671 - Elevation: 8039'. This species is found only in the following United States: CO, ID, MT, NV, UT, WY. It is classed as imperiled in the state of Montana.Plant -
Bloom season: June through AugustFoliage -
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