Mostly monoec. to dioec. herbs; infl. us. a compound or simple bracted umbel, sts reduced to heads. Fls regular, 5-merous; calyx adnate to ovary, lobes often obsolete; petals us. valvate and inflexed in bud; stamens alt. with petals, seated on epig. disk; anthers 2-celled, dehiscing lengthwise, us. inflexed in bud. Ovary inferior, 2-carpelled; carpels unilocular, with axile placentae. Ovules 1 per locule, pend.; styles 2, often swollen at base and forming stylopodia. Fr. a schizocarp of 2 mericarps cohering by their inner faces (commissure). Mericarps separating at commissural surface, us. remaining long suspended from the apex of a prolongation of the axis (carpophore); flattened to subterete, us. distinctly ribbed. Oil-tubes (vittae), if present, between or below the ribs. Seeds with minute embryo and cop. endosperm. Mostly biennial to perennial herbs with pith-filled furrowed stems; lvs alt., us. pinnately to palmately compound, with sheathing bases. About 130 genera and 3000 spp. of worldwide distribution.

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.