Herbs, usually annual, rarely perennial, 5–40 cm, glabrous except hirsutulous near base and sometimes on stem angles. Stems spreading-ascending, branching basally in inflorescence, sometimes throughout. Leaves: basal leaves opposite, or alternate throughout, spreading; stipular glands usually present; blade linear to linear-lanceolate, 10–25 × 1–4 mm, margins entire or few small teeth on distal leaves, not ciliate, apex acute; mostly 3-nerved. Inflorescences dense, ± flat-topped panicles. Pedicels 4–20 mm. Flowers: sepals deciduous, lanceolate, inner somewhat broader, 6–12 mm, margins of inner sepals densely and delicately glandular-toothed, outer ones scarious, conspicuously and more coarsely but less densely glandular-toothed than inner, apex acute or attenuate; petals yellow to orange, sometimes reddish below middle, broadly obovate, 11–19 mm; stamens 4–9 mm; anthers 1–2 mm; staminodia absent; styles connate nearly to apex, 6–9 mm; stigmas capitate. Capsules broadly ovoid to triangular-ovoid, tapering abruptly to flattened base, 3.6–4.7 × 3–4 mm, thick-or thin-walled, apex obtuse, dehiscing into 5, 2-seeded segments, segments blunt or subacute, persistent on plant, false septa complete, proximal part membranaceous, not terminating in loose fringe, distal part cartilaginous, margins not ciliate. Seeds 2.6–3.4 × 1–1.6 mm. 2n = 30.
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