Annual herbs or woody perennials, glabrous or hirsute. Leaves simple, 3–7-lobed or hastate, petiolate, stipulate, stipules often deciduous. Flowers bisexual, solitary or in racemes or panicles; epicalyx absent; calyx 5-lobed; 5- or 10-nerved; petals 5, free, white, lilac, purplish or yellow, equal to or exceeding the calyx; stamens numerous; styles equal in number to carpels (and mericarps); stigmas capitate. Fruit a flattened schizocarp; mericarps 5–20, 1-seeded, often beaked or spurred.
24 species from America, mostly Mexico; 1 species naturalised in Australia.