Annual or perennial herbs; stems without prickles. Lvs opposite, simple or often pinnate, mostly in basal rosettes. Infl. a flattened, hemispheric, or cylindric capitulum; involucral bracts usually linear-lanceolate, sometimes crowded, obtuse to acute; receptacular bracts lacking spines. Involucel-tube cylindric, 8-ribbed, expanding above at fruiting into a flattened, membranous corona with many veins. Calyx prolonged into 5 setae, persistent at fruiting. Corolla unequally 5-lobed; tube short, usually longer in marginal than central fls. Stamens 4. Fr. ovoid, ribbed, pitted, or obscurely angled, glabrous to hairy, bearing the corona and setae.