1Stipules caducous. Seeds 6 or fewer.
1'Stipules long-persistent. Ovules and seeds 9.
2Primary veins curving approximately parallel towards the margin at distances of 1-2 cm; secondary venation scalariform.
2'Primary veins few, independently curved towards the margin, secondary venation irregular.
3Inflorescences fasciculate (rarely stalked in R. anguifera).
3'Inflorescences on a peduncle (if racemose, see R. longiracemosa).
4Dorsal appendage of the anthers small. Style hairy. Fruit enveloped in moss-like appendages.
4'Dorsal appendage of the anthers distinct. Style glabrous. Fruit smooth.
5Anthers with small ventral appendages. Ovules 3. Fruit subglobose, with 3 seeds.
5'Anthers with ventral appendages about as long as the dorsal one. Ovules 6. Fruit conical, subtended by the expanded calyx, with 1 seed.
6Gynoecium glabrous. Petals to 4 mm long. Anthers with small dorsal appendage. Fruit triangular with rounded corners, 1-3 cm long, valves thick.
6'Gynoecium hairy. Petals to 9 mm long.
7Pedicels jointed near the base. Anthers with small dorsal appendage. Fruit subglobose to ovoid, 8-11 mm long, hairy, with a hairy style remnant.
7'Pedicels jointed about the middle. Anthers with a dorsal appendage 1-2 times as long as the cells. (Fruit unknown.).
8Inflorescences more or less elongate. Anthers with distinct ventral appendages. Fruit 1¼-4 cm ø.
8'Inflorescences fasciculate, or flowers densely set on a short rachis. Anthers with small or no ventral appendages. Fruit 0.5-1½ cm ø.
9Stipules 1-3½ mm long. Inflorescence axis ½-2½ cm long. Leaves often obovate.
9'Stipules (2-)4-21 mm long. Inflorescence axis to c. 10 cm long. Anthers often bearded at the base.
10Leaves petiolate, more or less concolorous. Anthers with a dorsal appendage about as long as the cells or longer.
10'Leaves subsessile, discolorous, pale underneath, 3½-6cm long. Anthers with a small dorsal appendage. Style hairy in the middle only. Ovary glabrous. Andamans, India?
11Leaves 1-7(-14) cm long. Petiole 1-5 mm. Plant dioecious; in the ♂ flowers only a style, in the ♀ flowers the anther cells vestigial, ovules 6.
11'Leaves 6-36 cm long. Petiole 5-35 mm. Flowers bisexual. Ovules 3.
12Stipules 1½-6 mm, scarcely striate. Leaves dark-coloured in the dried state. Fruit sparsely hairy.
12'Stipules 4-16 mm, distinctly striate. Leaves greenish in the dried state. Fruit glabrous.