Herbs, annual. Stem solitary, erect, 40-100 cm tall, simple or much branched in upper part, striate, sparsely pubescent. Leaves sessile, winged; blade lanceolate to oblong, 7-16 × 3-4 cm, both surfaces glabrous or shortly pubescent on veins, pinnately veined, basally gradually attenuate or subamplexicaul, margin irregularly coarsely dentate, apex acute or shortly acuminate. Capitula numerous, arranged in terminal corymb, ca. 15 × 1.5-1.8 mm. Involucres yellowish to brown-green, tubular, calyculate at base, bracteoles linear; phyllaries uniseriate, linear or linear-lanceolate, 8-11 × 0.5-1 mm, glabrous or sparsely pilose, margin narrowly scarious, apically acute or rather obtuse. Florets numerous, greenish or red tinged, tubular; outer florets uni-or biseriate, corolla filiform, 7-11 mm, 4-or 5-denticulate; central florets minutely tubular, 8-12 mm, 5-denticulate. Achenes cylindric, 2.5-3 mm, conspicuously ribbed. Pappus white, 7-8 mm. Fl. Jun-Oct.
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Annuals, (50–)100–200 cm (glabrous or unevenly coarse-tomentose, sometimes ± succulent). Taproots with tufts of fibrous roots. Stems 1(–2+), erect. Leaves evenly distributed (proximal often withering before flowering); indistinctly petiolate or subsessile; blades ovate-lanceolate to lanceolate, (3–)6–20 × (1–)2–8 cm, margins subentire to serrate or weakly lobed (distal leaves clasping, bractlike). Heads 2–20(–40) in ± corymbiform arrays. Involucres urceolate or obconic, 10–17 mm. Phyllaries usually 21. Receptacles (disclike, conspicuously expanded when fresh) 5–12 mm diam. Cypselae 2.3–3 or 4–5 mm, nerves 10–12 or 16–20, faces puberulent between nerves or glabrous.
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