| 1 | Inflorescences borne on stems and/or branches (cauli- or ramiflorous) |
| 1' | Inflorescences axillary |
| 2 | Indumentum whitish; peduncle broadened into a rim. — Widespread, in cultivation |
| 2' | Indumentum brownish or absent; peduncle not broadened into a rim. — Widespread, indigenous or in cultivation |
| 3 | Lamina deeply pinnately incised with 12-20 segments on each side, the incisions down to near the midrib. — Philippines |
| 3' | Lamina entire or pinnately incised, if deeply so and with up to 12 segments on each, then these mostly petiolulate |
| 4 | Staminate and pistillate inflorescences with peltate interfloral bracts |
| 4' | Staminate and pistillate inflorescences without interfloral bracts, or if present, then not peltate |
| 5 | Epidermis of petiole flaking off. — New Guinea |
| 5' | Epidermis of petiole persistent |
| 6 | Lateral veins 4-6 pairs; uncinate hairs on leafy twigs, petioles, and margin of the lamina (or glabrous). — Borneo |
| 6' | Lateral veins 6-20 pairs; straight and persistent hairs on leafy twigs, petioles, and margin of the lamina |
| 7 | Lamina of adult specimens incised down to the midrib, the segments often petiolulate. — Malay Peninsula, Sumatra, Borneo (and Philippines?) |
| 7' | Lamina of adult specimens entire or, if pinnately incised, then not down to the midrib |
| 8 | Lamina of adult specimens usually pinnately incised; petiole 3-9(-13); stipules usually 10-15 cm long. — Widespread |
| 8' | Lamina of adult specimens entire (or 3-lobed to -fid); petiole 1-3(-4) cm long; stipules 1-5(-8) cm long |
| 9 | Leafy twigs and stipules glabrous. — New Guinea |
| 9' | Leafy twigs and stipules hairy |
| 10 | Hairs on the stipules longer at the apex (subsericeous) than lower down (appressedly puberulous). — Widespread |
| 10' | Hairs on the stipules equally long |
| 11 | Lamina glabrous and both surfaces smooth. — Malay Peninsula, Sumatra, Borneo |
| 11' | Lamina hairy, at least beneath on the main veins, often scabrous or scabridulous above and/or beneath |
| 12 | Hairs on the leafy twigs appressed |
| 12' | At least some hairs on the leafy twigs ± patent |
| 13 | Stipules 0.5-1 cm long; lateral veins usually 7-10 pairs; lamina smooth above. — Borneo |
| 13' | Stipules 1-5(-8) cm long; lateral veins usually 10-20 pairs; lamina ± scabrous above |
| 14 | Peduncle of the pistillate inflorescences 5-14 cm long and the free parts of the perianth clavate, 8-12 mm long; head of staminate inflorescences 4-9 cm long. — Borneo, Philippines |
| 14' | Peduncle of the pistillate inflorescences 0.8-4 cm long and the free parts of the perianth cylindrical, 3-8 mm long; head of staminate inflorescences 1.5-3 cm long. — Sumatra, Malay Peninsula, Java, Borneo, Lesser Sunda Islands, Malay Peninsula |
| 15 | Lamina smooth above. — Sumatra, Borneo |
| 15' | Lamina ± scabrous above |
| 16 | Stipules 0.5-1(-2) cm long and petioles 1-1.5(-2) cm long; peduncle of the staminate inflorescences 1-3 cm long; peduncle of the pistillate inflorescences 2.5-3.5 cm long. — Malay Peninsula |
| 16' | Stipules 1-5(-8) cm long and petioles (1.5-)2-3 cm long; peduncle of the staminate inflorescences usually 3-13 cm long; peduncle of the pistillate inflorescences 5-14 cm long. — Borneo, Philippines |
| 17 | Surface of the staminate inflorescences sulcate or tuberculate, or the flowers intermixed with subulate processes and/or the pistillate inflorescences with numerous subulate to filiform interfloral processes, these at least 2 times longer than the free parts of the perianths |
| 17' | Staminate inflorescences with a smooth surface and the pistillate inflorescences without interfloral processes or if processes present, then few and less than 2 times as long as the perianths, or else c. 3 times as long as the perianths and pyramidate |
| 18 | Lateral veins (13-)18-24 pairs, rarely branched or forked away from the margin; stipules 3-9 cm long; petiole 3.5-4 cm long. — Borneo |
| 18' | Lateral veins (6-)10-16(-18) pairs, most or some of them branched or forked away from the margin, or if rarely branching, then the stipules 0.7-2 cm long and petiole 1-3 cm long |
| 19 | Leafy twigs 2-3 mm thick; stipules 0.7-2 cm long; lateral veins rarely branched or forked away from the margin; peduncle of staminate inflorescences 0.3-2 cm long; peduncle of pistillate inflorescences 0.3-0.8 or 1-4 cm long, brown velutinous. — Malay Peninsula, Sumatra, Borneo |
| 19' | Leafy twigs 2-20 mm thick; stipules mostly longer than 2 cm; lateral veins mostly branched or forked away from the margin; peduncle of staminate inflorescences usually more than 2 cm long, and of pistillate inflorescences more than 4 cm long or if less than 4 cm long, then minutely whitish puberulous |
| 20 | Hairs on vegetative parts minute to short, appressed and white, except for the brown subsericeous apex of the stipules; staminate inflorescences with subulate interfloral processes. — Widespread |
| 20' | Hairs on vegetative parts predominantly brown, on the stipules not distinctly different in length and colour; staminate inflorescences without subulate interfloral processes |
| 21 | Hairs on petioles and peduncles ± patent; indumentum on processes of the pistillate inflorescences partly hirtellous. — Borneo, Philippines, Celebes, Moluccas |
| 21' | Hairs on petioles and peduncles appressed; indumentum on processes of the pistillate inflorescences puberulous to hispidulous. — Sumatra, Malay Peninsula, Java, Borneo, Philippines (Palawan), Lesser Sunda Islands |
| 22 | Petiole 3-7(-10) mm thick, (2.5-)3.5-10 cm long; stipules often longer than 10 cm and brown hirsute |
| 22' | Petiole 1-3 mm thick, mostly 1-3.5 cm long, or if up to 5 cm long, then the hairs on the stipules appressed; stipules up to 8 cm long |
| 23 | Lamina of adult specimens mostly pinnately incised; areoles of lamina flat beneath. — Widespread |
| 23' | Lamina of adult specimens usually entire; areoles of lamina bullate beneath. — Widespread |
| 24 | Lateral veins 7-10 pairs |
| 24' | Lateral veins 10-20 pairs |
| 25 | Hairs on the stipules becoming longer towards the apex. — Widespread |
| 25' | Hairs on the stipules about equally long |
| 26 | Indumentum on leafy twigs predominantly brown(ish); petiole 1-2 mm thick. — Sumatra, Malay Peninsula, Borneo |
| 26' | Indumentum on leafy twigs predominantly whitish; petiole 2-3 mm thick. — Borneo |
| 27 | Petioles and peduncles with (longer) uncinate hairs. — Malay Peninsula |
| 27' | Petioles and peduncles without uncinate hairs |
| 28 | Stipules 6-18 cm long; petiole 3-8 cm long. — Philippines |
| 28' | Stipules usually 0.7-5 cm long; petiole 1-3.5 cm long |
| 29 | Stipules 0.7-2 cm long; petiole 1-2 mm thick; indumentum predominantly brown(ish). — Sumatra, Malay Peninsula, Borneo |
| 29' | Stipules usually 2-6 cm long; petiole usually 2-3 mm thick, or if 1-2 mm thick, then the indumentum predominantly whitish |
| 30 | Hairs of the stipules becoming longer towards the apex. — Widespread |
| 30' | Hairs of the stipules about equally long — Borneo. |
