Umbels simple, bracts 0 or minute. Fls. 5-merous; calyx-teeth us. obsolete; stamens inflexed in bud; styles filiform. Fr. laterally much-compressed, commissure very narrow, carpophore 0. Vittae 0 or sunk in primary rib or replaced by ± continuous oil-bearing layer. Mericarps with us. 1 (often obscure) rib on face. Seed invested by woody covering. Small perennial herbs. A widespread genus of some 75 spp., sts treated as constituting a separate family-Hydrocotylaceae. The N.Z. spp. are perennial herbs, often forming large patches; stems ± slender, branching, creeping, rooting at nodes; lvs us. clustered at nodes, simple to 3-5-foliolate, of ± orbicular-reniform order; stipules scalelike.

2n = c. 160

2n = c. 96

2n = 72

Glabrous or hairy, annual or perennial herbs, creeping and rooting at nodes. Lvs simple, ± entire to serrate, crenate, or palmately lobed or palmately 3-5-foliolate, petiolate, stipulate. Umbels simple or with successive whorls of fls; bracteoles small or 0. Petals white or green, tinged yellow or pink, with apex entire, acute, and not inflexed; calyx teeth small or 0. Fr. strongly laterally flattened and narrowed to commissure; mericarps orbicular or ovate; dorsal ribs acute, furrowed or obsolete; lateral ribs slender, acute, furrowed, or rarely obsolete; vittae in primary ribs or 0.