Lepidium alyssoides var. angustifolium (C. L. Hitchcock) Rollins; L. alyssoides var. junceum Rollins; L. alyssoides var. minus Thellung; L. alyssoides var. polycarpum Thellung; L. alyssoides var. streptocarpum Thellung; L. montanum Nuttall subsp. alyssoides (A. Gray) C. L. Hitchcock; L. montanum var. alyssoides (A. Gray) M. E. Jones; L. montanum subsp. angustifolium (C. L. Hitchcock) C. L. Hitchcock; L. montanum var. angustifolium C. L. Hitchcock; L. tortum L. O. Williams

Perennials or subshrubs; (woody base often aboveground); glabrous or minutely puberulent. Stems few to several from base, erect to ascending, branched throughout, (0.7-)1-4.8(-6.1) dm. Basal leaves often not rosulate; petiole 1-6 cm; blade pinnately lobed, (1-)1.5-8(-11) cm × (5-)10-35 mm, margins (of lobes) entire or denticulate. Cauline leaves sessile; blade linear, (0.8-)1.3-7(-9.5) cm × (0.7-)1-2(-3) mm, base attenuate, not auriculate, margins entire. Racemes elongated in fruit; rachis puberulent or glabrous. Fruiting pedicels divaricate to horizontal, straight or recurved to somewhat sigmoid, (terete), 3.5-8(-11) × 0.2 mm, glabrous or puberulent adaxially. Flowers: sepals ovate to oblong, 1-2 × 0.8-1 mm; petals white, suborbicular, 2-3 × 1-2 mm, claw 0.5-1.5 mm; stamens 6; filaments 1.5-2 mm, (glabrous); anthers 0.2-0.4 mm. Fruits broadly ovate, 2-3.7(-4.3) × (1.5-)1.8-2.9(-3.4) mm, apically winged, apical notch 0.1-0.3(-0.4) mm deep; valves thin, smooth, not veined, glabrous; style 0.2-0.6 mm, exserted beyond apical notch. Seeds ovate, 1.5-1.8 (-2) × 0.9-1.2(-1.5) mm. 2n = 32.

Flowering May-Jul. Pinyon-juniper or sagebrush communities, prairies, grasslands, sandstone outcrops, gypsum flats, sand dunes, dry flats and river bottoms, gravelly roadsides; 1200-2800 m; Ariz., Colo., Nev., N.Mex., Tex., Utah, Wyo.; Mexico (Chihuahua, Coahuila, Nuevo León, San Luis Potosí).

Of the five varieties of Lepidium alyssoides recognized by R. C. Rollins (1993), one (var. mexicanum Rollins) is a short-tufted form of the species restricted to Mexico that does not seem to merit recognition, another (var. junceum) is a glabrescent form of the type variety, a third (var. eastwoodiae) is treated below as a distinct species, and the fourth (var. angustifolium) is included here within L. alyssoides.