| 1 | Female inflorescence subsessile |
| 1' | Female inflorescence pedunculate. |
| 2 | Male inflorescence umbellate. |
| 2' | Male inflorescence of dichasia, pleiochasia or panicles. |
| 3 | Leaves elliptic to broadly elliptic (mostly under 10 cm long: W. Sepik Prov.) |
| 3' | Leaves oblanceolate to narrowly elliptic (mostly longer than 10 cm). |
| 4 | Male receptacle globose (Papua New Guinea, east of 146°30' E) |
| 4' | Male receptacle discoid. |
| 5 | Leaves narrower than 4.5 cm (W. Irian) |
| 5' | Leaves wider than 7 cm (W. Irian) |
| 6 | Pedicels of male flowers mostly in irregular clusters. |
| 6' | Pedicels of male flowers mostly solitary. |
| 7 | Nodes dilated, with a pore inhabited by ants (W. Irian). |
| 7' | Nodes not harbouring ants. |
| 8 | Male receptacle globose |
| 8' | Male receptacle turbinate with a 4-lobed apical disc |
| 9 | Leaves large Inflorescence large with stout pedicels (Solomon Is. and Papua New Guinea east of 48°30' E) |
| 9' | Leaves smaller (to 10 cm long). Inflorescence small, with slender pedicels (Wau, Goilala & Moresby Prov.) |
| 10 | Receptacles discoid or turbinate. |
| 10' | Receptacles globose (or only slightly depressed). |
| 11 | Leaves 20 cm long or longer (widely distributed) |
| 11' | Leaves considerably shorter. |
| 12 | Male inflorescence 1-2-flowered. Leaf 6 cm long or shorter (W. Irian, Idenburg R.) |
| 12' | Male inflorescence with more flowers. Leaf longer than 6 cm. |
| 13 | Male receptacle turbinate (W. Irian, W. Sepik) |
| 13' | Male receptacle patelliform (Central Prov.) |
| 14 | Leaves usually moderate to large (10-32 cm long) and entire (widely distributed, mainly at lower altitudes, but reaching up to 2450 m) |
| 14' | Leaves variable in size (usually under 15 cm long, but up to 21 cm), usually coriaceous, often dentate, but also entire when narrow (widely distributed, usually above 1200 m) |
| 14'' | Leaves 5-10 cm long, coriaceous, ± rugose, entire (Chimbu & Eastern Highlands Prov., above c. 2400 m) |
| 14''' | Leaves 5-10 cm long, chartaceous, usually narrowly elliptic, acuminate, entire or dentate (Wau, Goilala & Moresby Prov.) |
