Perennials; caudex simple, (thickened with persistent leaf bases); densely (silvery) pubescent, trichomes 5- or 6-rayed, rays furcate or 3-branched. Stems simple or few to several from base, prostrate, (from below a terminal rosette of leaves, unbranched), 0.2-0.5 dm. Basal leaves: blade elliptic to broadly ovate or obovate, (1-)1.5-2.5(-3) cm, margins entire, (apex obtuse). Cauline leaves: blade spatulate, 3-7 mm, (base cuneate), margins entire. Racemes not loose, (scarcely elongated in fruit, 3-5-flowered). Fruiting pedicels (straight or slightly curved). Flowers: sepals (yellow-green), narrowly elliptic to narrowly long-triangular, 3.7-5 mm; petals oblanceolate to nearly obovate, 7-8.5 mm, (abruptly tapering to narrow claw). Fruits wider than long, apex truncate to shallowly notched, compressed (angustiseptate), 3-4 mm; valves densely pubescent, trichomes ascending to erect, sparsely pubescent inside; ovules 4 per ovary; style 2-3 mm. Seeds plump, (slightly compressed).

Flowering Jun-early Aug. Steep slopes, dry summits, rocky fellfields, dry ledges; of conservation concern; 2700-2900 m; Mont.

Physaria humilis is found in metamorphosed rock and detritus on the peaks of the Bitterroot Mountains.