Annuals (coarse), 10-200+ cm. Stems erect, branched. Leaves cauline; mostly alternate (proximal 2-6 sometimes opposite); petiolate; blades lanceolate, linear, ovate, rounded-deltate, or suborbiculate, often ± palmately or pinnately lobed, ultimate margins entire or ± toothed, faces hirtellous or ± strigose, usually gland-dotted as well. Heads discoid, either pistillate (proximal) or functionally staminate (distal), in racemiform to spiciform arrays or borne singly (in axils). Pistillate heads: involucres ± ellipsoid, 2-5+ mm diam. at anthesis (6-20+ mm diam. at maturity); phyllaries 30-75+ in 6-12+ series, outer 5-8 distinct, the rest (sometimes interpreted as paleae) proximally connate, their distinct tips mostly ± hooked (the distal 1-3 usually longer, stouter, and not hooked), the whole becoming a hard, prickly perigynium (a bur); florets 2, corollas 0. Staminate heads: involucres ± saucer-shaped, 3-5 mm diam.; phyllaries 6-16+ in 1-2+ series, distinct to bases; receptacles conic to columnar; paleae spatulate to cuneiform or linear, membranous, distally ± villous or hirtellous; florets 20-50+, corollas whitish, ± funnelform, lobes 5, erect or reflexed (filaments connate, anthers distinct or weakly coherent). Cypselae (black) ± fusiform, enclosed in obovoid to ellipsoid, hard, prickly, 2-chambered burs; pappi 0. x = 18.