Western bitter cress is a perennial with erect stems arising from short, thin rhizomes. The flower stems range from 0-40 cm in height, and the herbage is generally smooth or sparsely haired. The stems may be unbranched or branched, and they may be lax or erect. The several basal leaves are compound pinnate, with several pairs (2-3) of small, ovate leaflets and a larger (1-2 cm) rounded leaf at the tip. The several stem leaves are similar with 2-4 ovate to lanceolate leaflets with a large rounded terminal leaflet.
The 4 petals are white, and range from 3.5-5 mm long. The 4 sepals are 1-2 mm long. The seed pods are erect siliques from 2-3 cm long and 1-1.5 mm wide.
Western bitter cress is a plant of moist ground such as along streamsides and damp meadows.
Western bitter cress is found from Alaska south west of the Cascades to southern Oregon.
In the Columbia River Gorge, it may be found west of the Klickitat River between the elevations of 0'-2800'.