Annuals; not scapose. Stems unbranched or branched proximally, (0.3-)0.6-4.5(-6) dm, densely pubescent proximally, glabrous distally, trichomes simple, 0.5-1.3 mm, and stalked, 2-4-rayed, 0.1-0.5 mm. Basal leaves rosulate or not, petiolate; petiole ciliate throughout; blade oblong-obovate or oblanceolate, (0.4-)1-3.5(-5) cm × (2-)5-15(-20) mm, margins usually dentate to denticulate, rarely subentire, surfaces sparsely to densely pubescent with stalked, 2- or 3-rayed, and cruciform trichomes, 0.1-0.5 mm. Cauline leaves 4-12(-15); sessile; blade broadly ovate to oblong, margins dentate or denticulate, surfaces pubescent, abaxially as basal, adaxially with primarily simple, and 2- or 3-rayed trichomes. Racemes (10-)18-60(-92)-flowered, ebracteate, considerably elongated in fruit; rachis not flexuous (straight), glabrous. Fruiting pedicels divaricate, straight, 7-28 (-35) mm [(1.5-)2-7 times longer than fruit], glabrous. Flowers: sepals ovate, (0.7-)0.9-1.6 mm, sparsely pubescent, (trichomes simple); petals yellow, spatulate to oblanceolate, (1.2-)1.7-2.2(-2.5) × (0.4-)0.6-1 mm, (deeply notched); anthers broadly ovate to subreniform, 0.1-0.2 mm. Fruits oblong to elliptic or, rarely, oblong-oblanceolate, plane, slightly flattened, (3-)5-8 (-10) × 1.5-2.5 mm; valves glabrous or puberulent, trichomes simple, antrorse, 0.05-0.2 mm; ovules (30-) 36-60(-72) per ovary; style 0.01-0.1 mm. Seeds ovoid, 0.5-0.7(-0.8) × 0.3-0.4(-0.5) mm. 2n = 16. Flowering Apr-Jul. Rock outcrops, open wooded slopes, meadows and prairies, stream banks, roadsides, disturbed gravelly grounds, waste places; 0-2700 m; introduced; Alta., B.C., Man., N.W.T., Nunavut, Ont., Que., Sask., Yukon; Alaska, Calif., Colo., Idaho, Iowa, Mich., Minn., Mont., Nebr., Nev., N.Dak., Oreg., S.Dak., Utah, Wash., Wis., Wyo.; Europe; Asia; introduced also in Australia.

Notes: stellate hairs on herbage, hairs branched or simple References: Hickman ed., The Jepson Manual. A Utah Flora. ASU Specimans