Annuals or biennials; caudex simple or branched, (relatively small, cespitose); densely pub-escent, trichomes (spreading, sessile or short-stalked), 5-7- rayed, rays distinct and simple, (tuberculate, finely tubercled with a U-shaped notch on one side). Stems simple or few to several from base, erect or decumbent, (rarely branched, usually leafy), to 4 dm. Basal leaves: blade lyrate-pinnatifid, 1-7 cm, margins entire or shallowly dentate. Cauline leaves (sessile or shortly petiolate); blade narrowly obovate to elliptic, 0.5-6 cm, margins entire, repand, or shallowly dentate. Racemes dense, (elongated in fruit, often subtended by distal cauline leaves). Fruiting pedicels (usually divaricate-spreading, straight or slightly curved, delicate, sometimes drooping, especially on herbarium specimens), 7-10 mm, (somewhat rigid). Flowers: sepals elliptic, 3.7-7.2 mm, (lateral pair somewhat cucullate, median pair thickened apically); petals (yellow to orange-yellow), obovate to obdeltate, (4.5-)7-10(-11) mm, (tapering to short claw, apex often emarginate). Fruits (sessile or substipitate), globose or broadly obovate, not inflated, 4-6 mm, (smooth); valves (not retaining seeds after dehiscence), glabrous; replum as wide as or wider than fruit; ovules 8-16 per ovary; style 2-5 mm. Seeds flattened. 2n = 14. Flowering Mar-May. Sandy, granitic, or calcareous soils, sandy ledges, limestone outcrops, rocky prairies, uplands; 30-400 m; Tex. Alyssum densiflorum (A. Gray) Kuntze (1891), not Desfontaines (1808) is an illegitimate name, sometimes found in synonymy with Physaria densiflora.