Arcane milk-vetch is a perennial wildflower with a cluster of spreading to erect stems from 5-15 cm tall. The leaves and stems are greenish and minutely haired with the hairs stiff and appressed to the stem or blade. The pinnately compound leaves are 3.5-10 cm long with 7-13 leaflets that are linear to oblong-elliptic in outline and 2-12 mm long. The leaf petioles are slender but stiff.
The inflorescence is a 5-15 flowered raceme from 1-6 cm long. The bell-shaped calyx is 3.5-5.5 mm long with black and white hairs appressed to the tube. The narrow to broad calyx teeth are awl-shaped and measure 0.4-1.6 mm long. The corolla is whitish-yellow, dirty white or whitish tinged with lilac. The banner is 7-10.5 mm long while the wings are up to 9.5 mm long while the keel is slightly longer than the wings. The nearly sessile pod is held erect. It is linear-oblong in outline and straight, and measures 12-25 mm long and 2.5-3.5 mm wide.
Arcane milk-vetch may be found on rocky flats, hillsides and ridge amongst low sagebrush between the elevations of 1100-2400 meters.
Arcane milk-vetch may be found from the Burnt, John Day and Deschutes Rivers of central Oregon and southward to the foothills to the east of the Cascade Mts. of California. It is found eastward through southeastern Oregon to southern Idaho and northern Nevada.
The photo above shows the scurfy surface to the leaflets of arcane milk-vetch. Photographed near Picture Rock Pass on Oregon Highway 31..........July 12, 1998.