| 1 | Leaves 13-28 by 5.5-10 cm. Twigs at apex 4 mm diameter. Swamp forest. — Sumatra. |
| 1' | Leaves up to 20 by 8.5 cm. Twigs at apex 1.5-3 mm diameter. |
| 2 | Twigs 1.5-2 mm diameter, striate. Leaves chartaceous or thinly coriaceous, drying greenish or brownish, with prominent venation above. Leaf base attenuate. Anthers 8-11. Fruits 1.5-2.5 cm; fruiting pedicel 7-15 mm long. — Lowland, but not in peat swamp forest. |
| 2' | Twigs 2-3 mm diameter, not or but little striate. Leaves thinly to thickly coriaceous, drying brownish, with venation prominent or not above. Leaf base ± rounded, sometimes attenuate. Anthers (7-)10-14. Fruits 1.7-4 cm; fruiting pedicel 3—9(—12) mm long. — Lowland peat swamp forest or montane forest. |
| 3 | Leaves drying greenish, with the nerves and venation paler and contrasting above. — Peninsular Malaysia. |
| 3' | Leaves drying more brownish, the nerves and venation not or but faintly paler, and little contrasting above. — Philippines. |
| 4 | [Venation on upper leaf surface little prominent, distinct or indistinct.] Fruits 1.7-2 cm long. |
| 4' | Fruits 3-4.5 cm long. Plant usually from montane area. |
| 5 | Indumentum of lower leaf surface consisting of scattered scale-like hairs 0.1 mm. — Lowland peat swamp forest or kerangas. |
| 5' | Indumentum of lower leaf surface consisting of mixed sessile hairs, 0.1 mm, and few elongate hairs, to 0.3 mm. — Montane areas. |
| 6 | Venation on upper leaf surface prominent and distinct; blade thinly or thickly coriaceous, base generally rounded. Fruits 3-4 cm, apex (subacute or) rounded. Usually in montane forest, at (100-)900-2000 m. — Borneo. |
| 6' | Venation on upper surface fine and hence indistinct; blade chartaceous (subcoria-ceous), base attenuate. Fruits 3.5-4.5 cm long, apex (sub)acute. Hill forest at 750 m. — Eastern W Kalimantan. |
