| 1 | Margin of lamina with glands. — Sumatra, Borneo |
| 1' | Margin of lamina without glands |
| 2 | Lower surface of lamina hairy in the areoles, ± glaucous when fresh |
| 2' | Lower surface of lamina hairy only on the venation |
| 3 | Indumentum on veins of lower surface of lamina whitish. — Sumatra, Malay Peninsula, Borneo, Java, Lesser Sunda Islands |
| 3' | Indumentum on veins of lower surface of lamina brown. — Sumatra, Malay Peninsula |
| 4 | Lamina ± densely hairy on midrib above and venation beneath |
| 4' | Lamina sparsely hairy to subglabrous on midrib above and venation beneath |
| 5 | Petiole 0.2-0.8 cm long and (2-)3-4 mm thick; indumentum brown. — Borneo |
| 5' | Petiole at least 0.8 cm long, or if shorter, then c. 1.5 cm thick and the indumentum whitish (and occurring in New Guinea) |
| 6 | Lateral veins 6-10 pairs |
| 6' | Lateral veins 10-20 pairs |
| 7 | Apex of the lamina rounded, leafy twigs for the greater part sparsely hairy, petiole 0.8-1.5 cm long. — Borneo |
| 7' | Apex of the lamina acuminate, or if rounded, then the leafy twigs densely hairy and the petiole usually 3-7 cm long. — Widespread |
| 8 | Lateral veins for the greater part furcate far from the margin or branched. — Philippines |
| 8' | Lateral veins not or sometimes one or few furcate far from the margin. |
| 9 | Epidermis of petiole flaking off; margin of lamina entire. — Borneo |
| 9' | Epidermis of petiole (usually) persistent; margin of the lamina (usually) denticulate towards the apex, at least at the acumen. — Widespread |
| 10 | Lamina ± scabrous beneath; base of lamina often minutely auriculate. — Celebes, Moluccas |
| 10' | Lamina (usually) smooth beneath; base of lamina never auriculate |
| 11 | Lateral veins 5-10(-11) pairs |
| 11' | Lateral veins (8-)10-20 pairs |
| 12 | Head of staminate inflorescence ellipsoid to obovoid, 1-1.5(-2) cm diam. and infructescence to c. 8 cm diameter. — Philippines |
| 12' | Head of staminate inflorescence subglobose, or if ellipsoid to obovoid, then 0.2-0.5 cm diam. and infructescence to c. 4.5 cm diameter. — Philippines |
| 13 | Peduncle of staminate inflorescence 1.2-1.7 cm long, peduncle of pistillate inflorescence (in fruit) 2.5-5.5 cm long. — Celebes, Moluccas |
| 13' | Peduncle of staminate inflorescence 0.1-0.4 cm long; peduncle of pistillate inflorescence (in fruit) 0.1-0.5(-2.5) cm long. — Sumatra, Malay Peninsula, Borneo, Philippines, New Guinea |
| 14 | Peduncle of staminate inflorescence 0.5-1.7 cm long and peduncle of pistillate inflorescence (in fruit) 1.5-4.5 cm long. — Sumatra, Malay Peninsula, Java, Philippines |
| 14' | Peduncle of staminate inflorescence 0.1-4 cm long and peduncle of pistillate inflorescence (in fruit) usually 0.1-0.5 cm long (or in Borneo up to 2.5 cm long, but then the epidermis of the petiole flaking off instead of persistent). — Sumatra, Malay Peninsula, Borneo, Philippines, New Guinea |
