| Astragalus osterhoutii | |
|---|---|
| Conservation status | |
|
Critically Imperiled (NatureServe) |
|
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Rosids |
| Order: | Fabales |
| Family: | Fabaceae |
| Genus: | Astragalus |
| Species: | A. osterhoutii |
| Binomial name | |
| Astragalus osterhoutii M.E.Jones |
|
Astragalus osterhoutii is a rare species of milkvetch known by the common name Osterhout milkvetch. It is endemic to Grand County, Colorado, where it is known from a few populations in Middle Park, a mountain basin.[1] There are five or six occurrences.[2] It is a federally listed endangered species.
The plant grows on sagebrush badlands on soils originating from the Niobrara Formation and the Pierre Shale. The gray-brown shale and siltstone clay soils are high in selenium, which the plant concentrates, causing it to develop a foul odor.[3]
This is a perennial herb producing many slender, erect, green stems up to a meter tall. The leaves are made up of several narrow linear leaflets up to 3 centimeters long. The inflorescence bears cream-colored, pealike flowers each over 2 centimeters long. The fruit is a flattened legume pod up to 4 centimeters long.
Threats to the species include flooding and reservoir creation, which have eliminated at least one occurrence.[2][3] All-terrain vehicle use and oil and gas exploration activities damage the habitat occupied by the plant.[2][3]