| 1 | Stems weak, filiform (0.5 mm wide), creeping, rooting at the nodes; leaves opposite; petals yellow |
| 1' | Stems stout, often fleshy, erect or spreading, not rooting at the nodes; leaves alternate; petals white,yellow, pink or purple |
| 2 | Leaves obovate or spathulate, flat; nodes glabrous or with few stipular hairs; petals yellow |
| 2' | Leaves linear to linear-oblong, terete or slightly flattened; nodal hair clusters usually conspicuous; petals white, pink or purple |
| 3 | Flowers often double; petals 1.5-2.5 cm long; seeds grey |
| 3' | Flowers simple; petals 3-6 mm long; seeds grey or black |
| 4 | Leaves 5-16(-27) x 1-4 mm; petals rose-purple; seeds black |
| 4' | Leaves 3-6 x 1-1.5 mm; petals white or whitish-rose; seeds grey to black |
