| 1 | Leaves membranous, 5-15(-20) cm long, drying greenish, apex acute or acuminate; nerves and venation distinct at both sides. Male buds tending to become partially glabrescent, with blunt or sharp angles. — Lowland forest. Sumatra, Peninsular Malaysia (anthers 17-25), Borneo (anthers 9-15). |
| 1' | Leaves membranous or chartaceous, 3.5-10 cm long, drying ± greenish brown to dark brown above; apex acute, acuminate, obtuse, or rounded; nerves and venation indistinct. Male buds with persistent indumentum, or partially glabrescent. Anthers 18-25(-30). |
| 2 | Male buds with minute mainly sessile stellate hairs, tending to be partly shed or easily rubbed off; angles sharp. Leaves drying dark brown above; apex obtuse, rounded, or subacuminate with obtuse tip. |
| 2' | Male buds with persistent indumentum of mixed sessile-stellate and dendroid hairs; angles rounded. Leaves drying ± greenish brown above; apex acute to acuminate. — Ridges in forest, often on sandy soils. Borneo. |
| 3 | Leaves membranous or chartaceous, elliptic to oblong. — Usually in lowland marshy forest. Sumatra, Peninsular Malaysia, Borneo. |
| 3' | Leaves chartaceous, lanceolate, with nearly parallel sides. — Ridges in lowland forest. Borneo (Brunei). |
