Annual to perennial, hispid or prickly herbs. Leaves angular, lobed or parted. Flowers axillary or terminal, in dense heads surrounded by large, deeply cordate bracts. Epicalyx segments usually absent. Calyx 5 dentate, cupular. Petals 5. Staminal column 5-toothed, short. Carpels 5; style branches 10. Mericarps 5, usually indehiscent.