Annual, biennial or perennial aromatic herbs, terrestrial or aquatic (not in Victoria), glabrous. Leaves 1-pinnate or divided ternately. Inflorescence a compound, leaf-opposed umbel; bracts and bracteoles absent. Flowers bisexual; sepals absent or minute; petals c. ovate, white, with a small inflexed tip; nectary short-conical or depressed. Fruit ovoid, laterally compressed; mericarps with 5 prominent ribs; carpophore persistent, shortly bifid.
About 20 species, cosmopolitan; 4 species (1 naturalised) in Australia.