Hydrocotyle L.
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.
Key
c. 100 spp., temperate and tropical. Native spp. 9, naturalised 1.
The native Hydrocotyle spp. are in urgent need of revision. The 3-foliolate group, which includes the sole naturalised sp., has been revised recently by Webb, C. J. and Johnson, P. N., New Zealand J. Bot. 20 : 163-168 (1982). The treatment of the simple-leaved spp. given here must be considered extremely provisional. Typical lf forms for all spp. are illustrated in Plate 7; ripe frs are also important for identification.
