Lepidium thurberi
Bull. Torrey Bot. Club 25: 259. 1898.
Annuals; pubescent, (trichomes cylindrical, to 1 mm, and much shorter, clavate ones). Stems often simple from base, erect, branched (several) distally, (0.8)1.2–4.9(–6) dm. Basal leaves (often withered at anthesis); rosulate; petiole 1–3(–4.5) cm; blade pinnatifid (lobes oblong to ovate or lanceolate), (1.4–)2.2–7(–10) cm, margins (of lobes) dentate-sinuate. Cauline leaves shortly petiolate; 1.5–6 cm × 6–25 mm, base not auriculate, margins (of lobes) entire or dentate. Racemes considerably elongated in fruit; rachis pilose, trichomes straight, cylindrical (to 1 mm) with much smaller, clavate ones, sometimes one type present. Fruiting pedicels divaricate-ascending to horizontal, straight or slightly recurved, (terete), 4–8(–10) × 0.2–0.3 mm, puberulent or pilose adaxially. Flowers: sepals suborbicular to broadly ovate, 1–1.6 × 0.7–1 mm; petals white, broadly obovate to suborbicular, 3–4 × 1.2–2.2 mm, claw 0.7–1.3 mm; stamens 6; filaments (median pairs) 1–1.6 mm, (glabrous); anthers 0.4–0.5 mm. Fruits broadly ovate to orbicular, 2–2.9 × 2–2.8 mm, apically winged, apical notch 0.1–0.2 mm deep; valves thin, smooth, not veined, glabrous; style 0.3–0.8 mm, exserted beyond apical notch. Seeds ovate-oblong, 1.3–1.6 × 0.8–1.1 mm.
Phenology: Flowering Apr–Aug.
Habitat: Salt flats, mesquite and creosote bush communities, playas, stream banks, sandy deserts, washes, clay bottoms, bluffs, gravelly granitic sand, grasslands, alluvial fans, roadsides, silty terraces, washes, gravelly flats
Elevation: 600-1800 m
Distribution
Ariz., Calif., N.Mex., Mexico (Chihuahua, Coahuila, Sonora).
Discussion
Selected References
None.