Perennials; caudex simple; densely pubescent, trichomes (appressed in layers), 5-7- rayed, rays usually bifurcate, sometimes furcate, (thickened toward center). Stems simple from base, prostrate to decumbent, (unbranched, from within and below leaf clusters, slender), 0.2-0.8 dm. Basal leaves (tufted, erect or ascending, silvery); blade linear to oblanceolate or (outer) oblanceolate to obovate or rhombic, 1.5-3.3 cm, (base sometimes subhastate), margins entire or dentate, (often involute). Cauline leaves: blade nearly linear, to 1.5 cm, margins entire. Racemes dense, (subcorymbose). Fruiting pedicels (recurved), 5-8 mm. Flowers: sepals (yellow-green), lanceolate, (2.5-)3.5-4.5 mm; petals spatulate to oblanceolate, 4-6.5 mm. Fruits (usually pendent), obdeltate, compressed (angustiseptate), 2-4 mm, (wider than long, base tapered to acute angle, apex truncate with inflated shoulders); valves densely pubescent; (septum obsolete or with a narrow fringe inside of replum, funicles attached close to replum apex); ovules 4 per ovary; style 2-4 mm, (slender). Seeds plump, (mucilaginous when wetted). Flowering Jun(-Jul). Clayey, silty, or gravelly soils, overlaying basalt lava flows, silty playas, sagebrush, barren areas; 1300-1700 m; Idaho. Physaria obdeltata is known from the eastern Snake River Plain.