Herbs perennial, aquatic or along water margins, glabrous throughout. Roots fascicled, fusiform or fibrous. Stem solitary, striate, branched, rooting at lower nodes. Basal leaves petiolate, sheathing; leaf blade 1-pinnate; pinnae sessile, remote. Umbels compound, terminal and lateral; bracts and bracteoles present, usually recurved; rays spreading-ascending. Calyx teeth conspicuous or minute, often unequal. Petals white, obovate or subround, base cuneate, apex notched with small incurved lobule, outer petals in umbellule sometimes enlarged (radiant). Stylopodium short-conic; styles divergent or reflexed. Fruit ovoid or ellipsoid, slightly compressed laterally, glabrous; ribs prominent, corky-thickened or obscure; vittae 1–3 in each furrow, 2–6 on commissure. Seed face plane. Carpophore 2-cleft to base.

About ten species: Africa, Asia, Europe, North America; five species (one endemic) in China.

(Authors: Pu Fading (溥发鼎 Pu Fa-ting); Mark F. Watson)