Herbs, annual. Stems prostrate to decumbent or ascending, to 1(–1.5) m, ± coarsely hirsute and sericeous with white or gray antrorse hairs, becoming glabrate. Leaves elliptic in outline, 1–6 × to 3 cm; stipules 5–7 × 1–3 mm; leaflets 6–10(–12), elliptic to oblong, 8–19 × 3.5–9 mm, middle pairs largest, surfaces appressed-hirsute, veins and margins sericeous. Pedicels 10–40 mm in flower and fruit, usually longer than, sometimes equaling, subtending leaves, thickened distally, straight or sharply bent at base and straight distally. Flowers 10–25 mm diam.; sepals persistent, lanceolate, 4–7 × 1–2 mm, 2/3 as long as petals, in flower longer than style, in fruit shriveling and turning brown, appressed to mericarps and reaching from top of fruit body to tip of style, margins becoming sharply involute, hispid and strigose; petals marcescent, 1-colored, orange, drying white to yellow, narrowly obovate, 5–12 × 3.5–5 mm; stamens as long as style; anthers yellow, usually ovoid, rarely linear, less than 1 mm; ovary ovoid, 1 mm diam., hairy; style cylindric, 1 mm, as long or longer than ovary, strigose or glabrous; stigma terminal. Schizocarps ovoid, 3–4 × 4–6 mm, strigose; beak cylindric, 3–9 mm, as long as to 3 times as long as fruit body, base scarcely conic, strigose or glabrous; mericarps 3–4 × 1 mm, abaxially rugose to tuberculate, tubercles if present all rounded, less than 1 mm, sides lightly to strongly pitted, adaxial edge angled.
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Annual; stems 3–6 dm, finely pubescent with incurved ascending hairs and ± coarsely hirsute; lvs 3–6 cm, short-petioled; lfls usually 4 pairs, elliptic or oblong, pubescent; peduncles 1–3 cm; fls 1 cm wide; fr-body ovoid, strigose, 4 mm, the beak slightly longer. Disturbed dry places, often along railways; Ill. to Ariz., s. to Mex. and C. Amer. (K. intermedia)