| 1 | Leaves simple, without lobes. |
| 2 | Petiole base without crests (New Guinea) |
| 2' | Petiole base with 1 or more crests. |
| 3 | Petiole base with several crests (Philippines) |
| 3' | Petiole base with a single collar-like crest. |
| 4 | Fertile flowers pedicelled (Philippines). |
| 4' | Fertile flowers sessile (or subsessile). |
| 5 | Leaf obovate to oblanceolate, petiole 3 cm or less |
| 5' | Leaf elliptic, petiole 5 cm or more |
| 6 | Leaf broadly obovate (Solomons) |
| 6' | Leaf lanceolate or narrowly obovate. |
| 7 | Pseudo-fruits pedicelled (Moluccas) |
| 7' | Pseudo-fruits sessile. |
| 8 | Inflorescence c. 60 cm ø (Moluccas) |
| 8' | Inflorescence c. 30 cm ø (New Ireland) |
| 8'' | Leaves lobed or digitately compound. |
| 9 | Leaves digitately compound. |
| 9' | Leaves lobed (sometimes smaller simple leaves below inflorescence). |
| 10 | Ovary 10-16-celled (New Guinea) |
| 10' | Ovary 4-5-celled. |
| 11 | Leaflets lobed (Philippines). |
| 11' | Leaflets entire. |
| 12 | Primary rays of inflorescence c. 10 or fewer |
| 12' | Primary rays of inflorescence more than 20. |
| 13 | Inflorescence c. 16-20 cm ø |
| 13' | Inflorescence c. 5-6 cm ø |
| 14 | Leaflets elliptic-oblong to ovate (Philippines) |
| 14' | Leaflets linear-lanceolate. |
| 15 | Leaflets 4-7, petiole 4-6 cm (Philippines) |
| 15' | Leaflets 9 or more, petiole longer than 10 cm (Borneo) |
| 16 | Pseudo-fruits sessile. |
| 16' | Pseudo-fruits pedicelled. |
| 17 | Petiolar crests long-pectinate. Bracts of the peduncle heavily setose (Philippines) |
| 17' | Petiolar crests fimbriate or undulate. Bracts of the peduncle not setose (Moluccas). |
| 18 | Lateral inflorescence branches with opposite, persistent bracts close to the base |
| 18' | Lateral inflorescence branches with scars of opposite caducous bracts near the middle |
| 19 | Lateral inflorescence branches without an articulation. |
| 19' | Lateral inflorescence branches with an articulation (2 bracts or bract-scars). |
| 20 | Petiolar base with a single collar-like crest (Borneo) |
| 20' | Petiolar base with several crests. |
| 21 | Petiolar crests long-pectinate. |
| 21' | Petiolar crests fimbriate or undulate. |
| 22 | Fertile flowers pedicelled. Stamens at least 7 (Key Is.) |
| 22' | Fertile flowers sessile (or subsessile). Stamens 5 (Bismarck Arch.) |
| 23 | Stamens and ovary cells more than 5. Flowers usually pedicelled (Moluccas) |
| 23' | Stamens and ovary cells 4. Flowers sessile or subsessile (Philippines). |
| 24 | Fertile flowers pedicelled. |
| 24' | Fertile flowers sessile (or if subsessile bracteoles longer than the very short pedicels). |
| 25 | Pedicels of fertile flowers longer than 7 mm (New Guinea) |
| 25' | Pedicels of fertile flowers 5 mm or shorter. |
| 26 | Ovary cells 7 or more. |
| 26' | Ovary cells 4-5. |
| 27 | Leaf lobes elliptic (Celebes) |
| 27' | Leaf lobes pinnatilobed (Batjan) |
| 28 | Petiolar crests ± entire (Philippines) |
| 28' | Petiolar crests with long setae. |
| 29 | Leaves coriaceous, margin thickened, teeth obtuse (Philippines). |
| 29' | Leaves membranaceous, margin not thickened, teeth setulose (Celebes) |
| 30 | Ovary cells 10 or more (New Guinea). |
| 30' | Ovary cells 6 or fewer. |
| 31 | Flower buds large (c. 9-12 mm long). Primary rays of inflorescence very strong |
| 31' | Flower buds smaller (c. 4-6 mm long). Primary rays of inflorescence more tenuous. |
| 32 | Heads of fertile flowers ± discoid at anthesis |
| 32' | Heads of fertile flowers globose |
| 33 | Leaf lobes lanceolate. |
| 33' | Leaf lobes broader. |
| 34 | Leaf lobes 4-7; petiole 4-6 cm (Philippines) |
| 34' | Leaf lobes 9 or more; petiole longer than 10 cm (Borneo) |
| 35 | Leaf surfaces retaining some trace of setulose tomentum. Umbellules of pseudo-fruits small (8 mm ø or less) (New Guinea) |
| 35' | Leaf surfaces glabrous at maturity. Umbellules of pseudo-fruits larger (1 cm ø or more). |
| 36 | Ovary cells 3 (Philippines). |
| 36' | Ovary cells 4 or more. |
| 37 | Petiolar crests ± entire |
| 37' | Petiolar crests long-pectinate |
| 38 | Umbellules of pseudo-fruits large (3-5 cm ø) (Philippines). |
| 38' | Umbellules of pseudo-fruits smaller (2½ cm ø or less). |
| 39 | Primary rays of the inflorescence 9-12 cm long. Leaves with strong radiating veins, usually more than 11 |
| 39' | Primary rays of the inflorescence 4-5 cm long. Leaf-veins less strongly developed, usually fewer than 11. |
| 40 | Leaf with a small triangular lobe below the middle of each side of the blade (not strictly palmately lobed) (Philippines) |
| 40' | Leaf palmately lobed. |
| 41 | Petiolar crests long-pectinate (Celebes) |
| 41' | Petiolar crests fimbriate, entire, or undulate. |
| 42 | Articulation of lateral branches of umbels close to the base (Talaud Is.) |
| 42' | Articulation of lateral branches of umbels near the middle. |
| 43 | Inflorescence over 20 cm ø (New Guinea) |
| 43' | Inflorescence under 20 cm ø (Philippines). |
| 44 | Leaf usually 3-lobed. Inflorescence rays delicate, indistinctly setose to glabrous |
| 44' | Leaf usually 5-7-lobed. Inflorescence rays sturdy, markedly setose |
