Perennials; caudex simple or branched; densely pubescent, trichomes (sessile or short-stalked), 4-7-rayed, rays usually furcate, sometimes bifurcate, (rough-tuberculate throughout). Stems few from base, erect with outer usually decumbent, 1-3.5(-5) dm. Basal leaves (erect); blade narrowly lanceolate to linear or (outer) oblanceolate, (1-)2-6(-9) cm, margins usually entire, rarely shallowly dentate, (inner involute, outer usually flat, base usually with some simple trichomes). Cauline leaves: blade narrowly oblanceolate to linear, (1-)2-4(-8) cm, margins flat or involute. Racemes compact, (elongated and loose in fruit, densely-flowered). Fruiting pedicels (usually recurved), (5-)10-20(-25) mm. Flowers: sepals oblong to broadly elliptic, 4-7(-8) mm, (lateral pair subsaccate, median pair cucullate); petals oblanceolate or obovate, (5-)6.5-9.5(-11) mm, (claw undifferentiated from blade, or blade gradually narrowed to claw). Fruits subglobose or obovoid, usually inflated, sometimes slightly compressed, (3-)4-6 mm; valves densely pubescent, trichomes spreading, usually pubescent inside, trichomes appressed, sessile; ovules (4-)8-12 (-16) per ovary; style 3-4.5(-6.5) mm. Seeds slightly flattened. 2n = 10, 20, 30. Flowering Apr-Jul(-Aug). Sandy or gravelly soils, steep hillsides, prairie pastures, clay slopes, limestone outcrops, sand dunes, open plains, sandy bluffs, rocky flats, white tuff sands; 0-1900 m; Ariz., Calif., Colo., Ill., Iowa, Kans., Minn., Mont., Nebr., Nev., N.Mex., N.Dak., Okla., S.Dak., Utah, Wis., Wyo. Material previously reported as Physaria ludoviciana from Canada (Alberta, Manitoba, Saskatchewan) is here included in 6a. P. arenosa subsp. arenosa. Lesquerella argentea (Pursh) MacMillan is a later homonym that has been used for P. ludoviciana.
Taprooted perennial with several erect or ascending stems 1-4 dm; basal lvs narrow, to 10 נ1 cm, entire or shallowly toothed, the cauline progressively smaller and not very numerous; racemes elongating to as much as 1.5 dm; pet 6-10 mm; ovules (2-)4-6(-8) per locule; pedicels elongating to 1-2 cm and soon becoming recurved; frs subglobose or obovoid, (3-)3.5-5.5(-6) mm, copiously and loosely stellate; style 3-5 mm; 2n=10, 30. Prairies, plains, and barrens; w. Ill. and e. Minn.; N.D. to Kans., w. to Mont., n. Ariz., and s. Nev. Apr.-Aug. (L. argentea, a preoccupied name)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.