Lepidium barnebyanum

Perennials; (cespitose, caudex thick, woody, numerous-branched, with persistent petiolar remains); puberulent. Stems simple or few from base (caudex), erect to ascending, unbranched or branched distally, (0.3-)0.5-1.5(-1.7) dm. Basal leaves not rosulate; petiole 0.3-0.8 cm, (papery); blade linear, (0.5-)1-7(-8) cm × 10-36 mm, margins entire. Cauline leaves sessile; blade linear, base attenuate, not auriculate, margins entire, (similar to basal, smaller distally). Racemes slightly elongated in fruit; rachis puberulent, trichomes straight. Fruiting pedicels divaricate-ascending, straight, (terete), 3-8 × 0.3-0.4 mm, puberulent throughout. Flowers: sepals (sometimes somewhat persistent), oblong-obovate, 1.8-2.8 × 1.3-1.8 mm; petals white to pale yellow, suborbicular to broadly obovate, 3.2-4.6 × 2.5-3.2 mm, claw 0.5-1.5 mm; stamens 6; filaments 1.8-2.6 mm, (glabrous); anthers 0.5-0.8 mm. Fruits ovate, 4-5.5(-6.2) × 3-3.8 mm, apically winged, apical notch 0-0.2 mm deep; valves thin, smooth, not veined, glabrous; style 0.5-1.2 mm, exserted beyond apical notch. Seeds ovate, 2.2-2.8 × 1.4-1.6 mm.

Flowering May-Jun. Pinyon-juniper and sagebrush communities, white sandy shale; of conservation concern; 1800-2000 m; Utah.

Lepidium barnebyanum is known from the Green River and Uinta Shale Formations in Duchesne County. It is in the Center for Plant Conservation´s National Collection of Endangered Plants.