Description: Shrubs or herbs, erect or spreading and rooting at the nodes, often aquatic with submerged parts bearing pneumatophores.
Leaves alternate or opposite, rarely whorled, usually entire.
Flowers usually solitary, occasionally clustered, in upper leaf axils or in an inflorescence, often with bracteoles; actinomorphic. Hypanthium not extended beyond the ovary. Sepals 4 or 5, persistent. Petals 4, 5 or 0, yellow or white.
Fruit an irregularly dehiscent capsule, loculi equal in number to sepals; seeds free or embedded in the endocarp.
Distribution and occurrence: World: 75 spp., Amer. & Old World. Aust.: 7 spp. (4 spp. native, 3 spp. naturalized, 1 sp. of doubtful status), all mainland States.
Text by J. M. Dalby
Taxon concept:
| | Key to the species | |
| 1 | Leaves alternate; stamens 8 or 10 | 2 |
| Leaves opposite; stamens 4 | 5 |
| 2 | Plants erect | 3 |
| Plants prostrate
Back to 1 | Ludwigia peploides |
| 3 | Fruit prominently 4- or sometimes 5-angled | 4 |
| Fruit ribbed, but ± terete
Back to 2 | Ludwigia octovalvis |
| 4 | Plant hairy; leaves up to 12 cm long | Ludwigia peruviana |
| Plant glabrous; leaves usually >12 cm long
Back to 3 | Ludwigia longifolia |
| 5 | Petals present; fruit 5–7 mm long | Ludwigia repens |
| Petals absent; fruit 2–5 mm long
Back to 1 | Ludwigia palustris |
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