Leonard and I maintain three tracts of up to seventeen acres each as wildlife or natural areas on our property (Modoc County CA). For over thirty years these areas have remained “untouched” and provide us with a bounty of plants and animals. Recently we found a single thread-leaved locoweed (Astragalus filipes) growing amid the sagebrush. Possibly a gift from a passing bird?
A member of the pea family, thread-leaved locoweed has many locally common names including basalt milkvetch and narrow pod locoweed. This native plant is found from British Columbia through California and east into Nevada, Idaho and Utah. The preferred habitat is the dry, open areas of the sagebrush steppe or amid open pines.
Unlike many locoweeds that grow close to the ground, thread-leaved locoweed is a more erect plant that resembles a small bush. The pinnate leaves are composed of widely spaced, slender leaflets. The leaflets occur in pairs and are linear with distinct points. At the base of the leaf, scale-like appendages form a papery sheath where the leaf attaches to the stem. This sheath can be seen in the stem and leaf photograph if one looks closely.
Depending on their age, identification of the flowers can prove to be a little confusing. Many identification guides that group flowers by color place thread-leaved locoweed amid the white flowers. However, the creamy white flowers fade to yellow with time, as in these photographs. The flowers are well spaced on the stalk.
The fruit of thread-leaved locoweed is a linear pod that resembles a pea pod.
More information about the genus Astragalus can be found in my previous post on wooly locoweed (Astragalus purshii).