Annuals, 4–45 cm. Stems 1, erect, simple or branched proximally and/or distally or 2–10, decumbent to ascending, and ± branched distally, glabrous or sparsely arachnose (sometimes only in leaf axils). Cauline leaves: proximal oblanceolate to narrowly obovate, usually pinnately lobed (lobes usually unequal, apices acute or obtuse), sometimes ± fleshy, ultimate margins entire or dentate, faces glabrous (proximalmost cauline usually more deeply divided); distal seldom notably reduced (sometimes pinnately lobed). Calyculi 0 (i.e., outer phyllaries intergrading with inner), or of 5–12+, oblong or ovate to lanceolate or linear bractlets, hyaline margins 0.1–0.3 mm wide. Involucres ± campanulate, 5–12 × 2–7 mm. Phyllaries 12–22(–40+, without calyculi) in 2–3(–5+) series, (usually red-tinged) lanceolate to linear, hyaline margins 0.05–0.2 mm wide, faces glabrous. Receptacles not bristly. Florets 10–123; corollas light to medium yellow, 5–17 mm; outer ligules exserted 1–10 mm. Cypselae ± cylindro-fusiform or ± prismatic, 0.9–1.7 mm, ribs extending to apices, ± equal or 5 more prominent than others; persistent pappi usually 0, rarely of 1–2 bristles. Pollen 70–100% 3-porate. 2n = 14.
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