Plants herbs, erect, annual, (2) 4–18 (22) dm tall, glabrous, bright green; stems with caudex absent, the aerial flowering stems erect, hollow and fistulose, 0.5–3.5 (5) dm long, glabrous, minutely glandular proximally, infrequently also short-hispid; leaves basal, the petioles 1–6 cm long, hirsute, the blades round to reniform, (0.5) 1–2.5 (4) cm long, (0.5) 1–2 (3) cm wide, short-hirsute on both surfaces and greenish, the margins plane; inflorescences cymose, open, spreading to erect, 30–150 (170) cm long, 10–80 cm wide, the branches usually fistulose, glabrous, the bracts 3, scalelike, 1–4 mm long, 1–2 mm wide; peduncles mostly spreading, straight, slightly bent distally, capillary, 1–4 cm long, glabrous; involucres turbinate, 1–1.5 (1.8) mm long, 0.6–0.9 (1.2) mm wide, glabrous, the teeth 4, erect, 0.3–0.5 mm long; flowers 1.5–2.5 mm long, the perianth yellow with greenish to reddish midribs, densely hirsute with coarse curved hairs, the tepals monomorphic, narrowly ovate, the stamens exserted, 0.9–1.5 mm long, the filaments glabrous or sparsely pubescent proximally; achenes light brown to brown, trigonous, 2–2.5 mm long, glabrous. 2n = 32.