Prostrate semi-aquatic to aquatic glabrous perennial herbs, sometimes rooting at nodes. Leaves pinnate, petiolate. Inflorescence a compound umbel, lateral; peduncles short to almost absent; bracts absent or several; bracteoles present, entire, triangular to lanceolate, obtuse. Flowers bisexual, white; sepals absent or inconspicuous; petals ovate, apex inflexed; nectary indistinct, flat. Fruit ovoid or globose, slightly laterally flattened; mericarps with 5 or 11 prominent ribs; carpophore entire.
5 species native to Europe, northern Africa and southern parts of west and central Asia; 1 species naturalised in Australia.
