| 1 | Flower buds pubescent at base. [Ovary pubescent. Fruits pubescent, ellipsoid, 2.5-4 cm long. Flowers in dense clusters and strongly fragrant in male specimens.] — Originating from Sri Lanka, cultivated in Penang, Singapore and elswhere |
| 1' | Buds glabrous or early glabrescent |
| 2 | Perianth 2-lobed. Ovary glabrous |
| 2' | Perianth 3- (or 4-)lobed. Ovary glabrous or pubescent |
| 3 | Twigs ridged or lined. Leaves membranous, often with irregular whitish blotches. Fruits and seeds globose. — Plant usually riverine, in coastal areas. |
| 3' | Twigs not lined. Leaves without pale blotches. Fruits and seeds ellipsoid |
| 4 | Leaves membranous, glabrous beneath, dots absent. — Gardens' Jungle, Singapore (originating from E Malesia) |
| 4' | Leaves coriaceous, beneath pubescent and with dots (lens!) — Kerangas, peat swamp forest |
| 5 | Leaves with dots beneath (dots not to be confused with smaller dark punctation) |
| 5' | Leaves without dots beneath |
| 6 | Leaves with persistent indumentum beneath |
| 6' | Leaves glabrous or glabrescent beneath |
| 7 | Ovary pubescent. Fruits pubescent or at least with vestigial indumentum near the base; perianth not persistent |
| 7' | Ovary glabrous or with some incidental minute hairs. Fruits glabrous, perianth (at least at first) persistent |
| 8 | Hairs on lower (and upper) leaf surface harsh, with hardened hair bases, in older leaves rendering the surface scabrous. Fruits 1-1.4 cm long. |
| 8' | Leaves not scabrous. Fruits 2 cm long or more |
| 9 | Twigs 3-5 mm diam. Leaf bud and twig apex with hairs 0.2-0.3 mm long. Leaf blade 13-21 cm long, [matt above on drying. Fruits 2.2-2.4(-3) cm long] |
| 9' | Twigs 5-10 mm diam. Leaf bud and twig apex with hairs 0.5 mm long or more. Leaf blade 20-40(-70) cm long |
| 10 | Leaf bud, twig apex and lower leaf surface with rather stiff, rust-coloured hairs 0.5-1 mm long. Fruits 3.8-5.5 cm long |
| 10' | Leaf bud, twig apex and lower leaf surface with yellow-brown or pale brown woolly hairs 1-2 mm long. Fruits 3 cm long |
| 11 | Twigs pale brown or straw, contrasting with the blackish petiole. Leaves either distichous or in 3-5 rows along the twigs |
| 11' | Twigs brown, not contrasting with the petiole. Leaves distichous |
| 12 | Leaves distichous or in 3 rows |
| 12' | Leaves in 3-5 rows along the twigs. [Pedicel not articulated. Fruits 3-5.5 cm long, perianth not persistent.] |
| 13 | Leaves distichous. Pedicel not articulated. Male perianth ± ellipsoid, 2-2.4 mm long. Fruits not known |
| 13' | Leaves distichous or in 3 rows. Pedicel articulated (this character best seen in male flowers). Male perianth globose, smaller. Fruits 2.5-3.5 cm long, perianth persistent |
| 14 | Leaf upper surface matt on drying caused by fine wrinkles; nerves flat or sunken. Fruits usually with persistent perianth |
| 14' | Leaves above not particularly matt, not finely wrinkled; nerves flat or raised. Perianth not persistent under the fruits |
| 15 | Lateral nerves flat or but faintly raised above |
| 15' | Lateral nerves distinctly raised above. [Pedicel articulated; this character best seen in male flowers.] |
| 16 | Leaf bud with hairs 1 mm long. [Midrib narrow, line-shaped, sunken above; blade margin rolled-in.] |
| 16' | Leaf bud with hairs much shorter |
| 17 | Leaf bud with hairs 0.1 mm long. Twigs 2.5-5 mm diam. Leaves 15-27 cm long. Pedicel not articulated |
| 17' | Leaf bud with hairs 0.2-0.4 mm long. Twigs 1.5-3.5 mm diam. Leaves 5-15 cm long. Pedicel articulated |
| 18 | Leaf bud with hairs 0.1 mm long. Midrib early glabrescent beneath. Fruits 4.5-6.5 cm long, with thick pericarp |
| 18' | Leaf bud with hairs 0.1 mm long or usually much longer. Midrib often late glabrescent beneath. Fruits 2-4 cm long, pericarp 2-5(-7) mm thick |
| 19 | Twigs ± angular, lined or low-ridged. [Fruits 2-3(-4) cm long.] |
| 19' | Twigs terete, neither lined nor ridged |
| 20 | Twigs 1-3 mm diam. Leaves membranous. Fruits 2.3-2.4 cm long |
| 20' | Twigs 2-5 mm diam. Leaves usually chartaceous. Fruits 1.9-3.5 cm long |
