Fl. S.E. U.S., 468, 1331. 1903.
Annuals or biennials; often densely hirsute, (trichomes cylindrical). Stems often simple from base, erect, branched distally, (1.5–)2–6.7(–9.4) dm. Basal leaves (later withered); rosulate; petiole (0.7–)1.5–4.5 cm; blade pinnatifid, 2–8.3 cm × 9–26 mm, margins (of lobes) entire or dentate. Cauline leaves shortly petiolate; blade oblanceolate to nearly linear, 1–4.5(–6.2) cm × 3–10(–17) mm, base attenuate to cuneate, not auriculate, margins entire or dentate. Racemes much-elongated in fruit; rachis pubescent, trichomes curved, with fewer and longer, straight ones. Fruiting pedicels usually divaricate, rarely horizontal, straight or slightly recurved, (terete), (2.5–)3–4.1(–4.7) × 0.2 mm, puberulent adaxially. Flowers: sepals oblong, 0.8–1 × 0.2–0.4 mm; petals (sometimes absent), white, oblanceolate, 0.4–1.6 × 0.1–0.8 mm, claw absent; stamens 2, median; filaments 0.8–1 mm; anthers 0.1–0.2 mm. Fruits elliptic-obovate to obovate-orbicular, 2.4–3.2 × 1.8–2.5 mm, apically winged, apical notch 0.2–0.5 mm deep; valves thin, smooth, not veined, sparsely puberulent, (trichomes often antrorsely appressed, sometimes restricted to margin); style 0.05–0.1 mm, included in apical notch. Seeds ovate, 1.4–1.6 × 0.7–0.9 mm.
Phenology: Flowering Mar–Jun.
Habitat: Disturbed grounds, railroad tracks and embankments, fields, knolls, stream banks, waste areas, open banks, roadsides, sandy terraces
Kans., La., Miss., N.Mex., Okla., Tex., Mexico (Coahuila, Nuevo León, San Luis Potosí).