22. Lepidium lasiocarpum Nuttall in J. Torrey and A. Gray, Fl. N. Amer. 1: 115. 1838.
Lepidium ruderale Linnaeus var. lasiocarpum (Nuttall) Engelmann ex A. Gray; Nasturtium lasiocarpum (Nuttall) Kuntze
Annuals; hirsute or hispid, (trichomes cylindrical). Stems usually few to several, rarely simple from base, erect to ascending or (outer ones) decumbent, branched distally, (0.15-)0.6-3(-3.8) dm. Basal leaves (later withered); not rosulate; petiole (0.4-) 1-3.5(-5) cm; blade spatulate to oblanceolate, lyrate-pinnatifid, pinnatisect, or 2-pinnatifid, (0.7-)1.5-4.5 (-7.5) cm × (9-)12-20(-30) mm, margins rarely dentate, (lobes) entire or dentate. Cauline leaves subsessile or petioles 0.8-2.2 cm, blade lanceolate to oblanceolate, (0.7-)1.2-3.3(-5) cm × (2-)4-12 mm, base cuneate, not auriculate, margins subentire to dentate. Racemes often considerably elongated in fruit; rachis hirsute or hispid, trichomes straight, cylindrical. Fruiting pedicels divaricate-ascending to horizontal, straight or slightly curved, (often strongly flattened), (1.8-)2-4(-4.6) × 0.2-0.7 mm (to 0.3 mm thick), hirsute to hispid throughout or adaxially. Flowers: sepals oblong, 1-1.3(-1.5) × 0.5-0.8 mm; petals (sometimes absent), white, oblanceolate to linear, (0.3-)0.6-1.5(-2) × (0.1-)0.2-0.5 mm, claw absent; stamens 2, median; filaments 1-1.4 mm; anthers 0.2-0.3 mm. Fruits ovate to ovate-orbicular, 2.8-4(-4.6) × 2.4-3.6(-4) mm, (base broadly cuneate to rounded), apically winged, apical notch (0.2-)0.3-0.6(-0.7) mm deep; valves thin, smooth, not veined, hirsute to hispid (on surface or margin); style obsolete or to 0.1 mm, included in apical notch. Seeds ovate, 1.4-2.2 × 0.9-1.4 mm.
Subspecies 3 (2 in the flora): w United States, n Mexico.
