Herbs, rarely shrubs or climbers. Lvs alternate, simple and entire to palmately or pinnately compound or lobed; stipules usually 0, sometimes present. Fls ☿ or unisexual, actinomorphic or sometimes outer fls irregular with enlarged outer petals, arranged in axillary or terminal, simple or compound umbels, these sometimes reduced to capitate heads. Calyx adnate to the ovary, with 5 teeth, conspicuous, minute or 0. Petals 5, free, variously inflexed or notched, rarely 0. Stamens usually 5, very rarely 2-4; filaments free; anthers 2-locular. Ovary inferior, usually 2-, very rarely 1-locular; styles 2, free, thickened at the base to form the nectary (stylopodium) over the ovary; ovules solitary, pendulous. Fr. dry, usually splitting down a septum (commissure) to form 2 mericarps, these often suspended from a central axis (carpophore); mericarps usually with 5 primary ribs and 4 secondary (often undeveloped) ribs between, oil canals (vittae) usually positioned in the furrows between the ribs; ribs variously hairy, winged or spinous.