Annuals, biennials, or perennials; caudex (or base) simple or branched (poorly developed); rarely scapose. Stems branched distally, (0.3-)0.5-3(-4.2) dm, pubescent proximally, often glabrous distally, trichomes simple, 0.1-1 mm, sometimes with fewer, stalked, 2-rayed ones. Basal leaves rosulate; shortly petiolate; petiole (0-0.5 cm), ciliate throughout; blade obovate to oblanceolate or linear-lanceolate, (0.3-)1-2.8(-3.5) cm × (1-)2-6(-9) mm, margins entire or denticulate, (ciliate, trichomes simple, 0.4-1 mm), surfaces usually pubescent, abaxially with stalked, 2-4-rayed trichomes, 0.05-0.4(-0.5) mm, (rarely with simple trichomes along midvein), adaxially with simple trichomes sometimes also with 2-rayed ones, 0.07-0.4 mm, rarely glabrous. Cauline leaves (0 or) 1-3(-5); sessile; blade lanceolate to elliptic or ovate, margins entire or denticulate, surfaces pubescent as basal. Racemes (2-)6-30(-50)-flowered, ebracteate, elongated in fruit; rachis straight or, rarely, flexuous, glabrous. Fruiting pedicels divaricate-ascending or horizontal, (not appressed to rachis), usually straight, rarely curved upward, (3-)5-14(-16) mm (subequaling or shorter than fruit), usually glabrous, rarely sparsely puberulent. Flowers (chasmogamous, petaliferous); sepals ovate, 1.4-2.1 mm, glabrous or sparsely pubescent, (trichomes simple); petals yellow, spatulate to oblanceolate, 2-3.2 × 0.7-1.2 mm; anthers ovate, 0.15-0.25 mm. Fruits lanceolate to narrowly elliptic or linear, plane, flattened, (4-)6-12(-15) × (1-)1.4-2.1 mm; valves glabrous; ovules (20-)24-38 (-44) per ovary; style 0.01-0.12 mm. Seeds oblong, 0.7-1 × 0.4-0.5 mm. 2n = 24. Flowering Jun-Aug. Open woodlands, pine forests, meadows, rocky knolls, alpine slopes, stream banks, disturbed areas; 900-3700 m; Alta., B.C., N.W.T., Yukon; Alaska, Ariz., Calif., Colo., Idaho, Mont., Nev., N.Mex., Oreg., Utah, Wash., Wyo.