| 1. Leaves opposite; sepals 4; petals 0 or 4, 13 mm, soon deciduous; stamens 4; fruits 110 mm, erect; seeds free from fruit wall (sect. Dantia) |
| |
| 2. Petals 0; sepals 12 mm; fruit 15 mm; pedicels 00.5 mm; ovary with 4 green stripes |
| L. palustris |
| 2' Petals 13 mm; sepals ± 25 mm; fruit 410 mm; pedicels 03 mm; ovary not striped |
| L. repens |
| 1' Leaves alternate; sepals 5(6); petals 5(6), 730 mm; stamens 10(12) in 2 unequal sets; fruit 1040 mm, reflexed; seeds embedded in fruit wall (sect. Oligospermum) |
| |
| 3. Stem generally ascending or erect (sometimes floating or creeping); bractlets obovate; petioles 323 mm; sepals (8)1319 mm; petals (15)2030 mm |
| L. hexapetala |
| 3' Stem generally floating or creeping; bractlets deltate; petioles 360 mm; sepals 312 mm; petals 724 mm |
| L. peploides |
| 4. Plants spreading-hairy; leaf tip glandular; fruit 2540 mm |
| subsp. montevidensis |
| 4' Plants generally subglabrous; leaf tip not glandular; fruit 1025 mm |
| subsp. peploides
|