The photo above shows silky crazyweed as seen atop Elk Hill in the eastern Bob Marshall Wilderness (about 1/2 mile east of the North Fork of the Sun River........July 25, 1999.
Also known as white locoweed, silky crazyweed is a low to moderately high perennial wildflower with one to several very short stems and a cluster of basal leaves atop a taproot. The stems and leaves are variously colored by whitish to greenish hairs, and plants are not sticky glandular. The pinnately compound leaves are 8-20 cm long with the petiole nearly as long as the blade. The 9-19 leaflets are each ovate, oblong-elliptic or lanceolate with obtuse to acute tips. Individual leaflets measure 15-30 mm long and 2-7 mm wide. The leaflets typically appear whitish, silvery or greenish white due to a dense covering of appressed hairs.
The flower stem is held above the basal tuft of leaves and varies from 15-30 cm high. It is topped by a raceme of 6-20 white to faintly yellowish flowers. The bracts subtending each flower are lanceolate in shape and measure from 4-13 mm long. The bell-shaped to slightly tubular calyx is 6.5-8.5 mm long with 5 narrow teeth measuring 1.5-4.5 mm long. These calyx teeth are roughly equal in length, but the two lowest teeth are the widest. The whitish corolla is sometimes pencilled with faint pink lines while the keel is usually purple-spotted near its base. The banner is roughly 18-26 mm long with the banner slightly reflexed backwards from the wings and keel. The wings are slightly shorter than the banner and up to 8 mm wide at their tip. The erect pods are sessile and oblong-ellipsoid or narrowly ovoid-ellipsoid in outline, tapering gradually to a slender, gently curved (to the side or back on itself) beak (See photo at right.). The pods measure 15-25 mm long and 4-7 mm wide and are slightly grooved ventrally. The pods appear fleshy green when new and are sparsely covered with light colored hairs.
Silky crazyweed may typically be found below elevations of 2200 meters in open dry grass and rocky habitats in the prairies, plains and foothills. It may also be found on rocky peaks and open pine forests up to elevations of 3300 meters.
Silky crazyweed may be found from southern British Columbia east to Saskatchewan and south through the Great Plains to western Oklahoma and central New Mexico. It is found less frequently westward into the Rocky Mts. to northeastern Nevada, Utah, central and southern Idaho and southeastern Oregon. This species is listed on the Oregon Plant Atlas, but without a currently published record.