Sierran peavine is a fairly attractive perennial wildflower with several stems arising from rhizomes and erect or clambering through foliage to lengths of 15-80 cm. The stems are angled but not winged and the stem and leaves are sparsely to fairly densely covered with soft hairs, especially on the calyces and undersides of the leaves. The leaves alternate along the stems and are pinnately compound. Individual leaves have 8-14 leaflets that are either paired or scattered. The leaflets are linear, ovate-lanceolate or lanceolate-elliptic in outline and measure from 2-12 cm long and 2-30 mm wide. The tendrils range from reduced and bristle-like to fairly well developed (in variety pilosellus) and are found at the tips of the leaves. The stipules are generally less than half as long as the leaflets and linear-lanceolate to lanceolate in outline and 2-lobed.
The raceme consists of 2-7 bluish to reddish-purple flowers with the banner typically darker than the wings or keel. The banner is sharply reflexed upwards from the axis of the corolla tube while the broad wings are roughly equal in length to the banner. The keel is 1-3 mm shorter than the wings. The calyx is 6-12 mm long and ranges from semi-glabrous to fairly hairy. The calyx teeth are unequal in length, with the upper pair the shortest and widest, measuring about 1/3-3/4 the length of the calyx tube. The pod measures 3-7 cm long and 4-9 mm wide.
Sierran peavine is typically found in open woods in the Columbia River Gorge.
Sierran peavine (var. pilosellus) is generally found west of the Cascade crest from British Columbia south to California.
In the Columbia River Gorge, variety pilosellus may be found between the elevations of 100'-4500' from near the Sandy River eastward to near the White Salmon River.
