| 1 | Leaves cordate at base; fruits drupe-like, with lateral ridges but without wings, slightly compressed |
| 1' | Leaves cuneate to attenuate at base; fruits distinctly winged, sometimes narrowly so but then fruits strongly flattened |
| 2 | Mature fruits with 3 zones across width (body; adjacent part of wing markedly thickened with spongy material and scarcely thinner than body; marginal thin part of wing) |
| 2' | Mature fruits with 2 zones across width (body; thin wing) |
| 3 | Leaves up to 22 cm long, secondary veins distant; fruit usually slightly longer than wide, glabrous |
| 3' | Leaves up to 14 cm long, secondary veins moderately spaced; fruit usually slightly wider than long, densely pubescent when young |
| 4 | Fruits 1-3.2 cm long, with wings 0.8-3.5 cm wide; style densely pubescent at least basally |
| 4' | Fruits 0.5-1.2(-1.5) cm long, with wings 0.2-1 cm wide; style glabrous, or very sparsely pubescent near base |
| 5 | Inflorescence 1.5-5.5 cm long, with rhachis 0.8-3.5 cm long; disk sparsely pilose |
| 5' | Inflorescence 9-17 cm long, with rhachis 8-14 cm long; disk pubescent |
| 6 | Leaves chartaceous-subcoriaceous, domatia present, tertiary veins closely and regularly percurrent; fruit wider than long, with 2-5 wings, if more than 2 then 2 much wider than the others |
| 6' | Leaves strongly coriaceous, domatia absent, tertiary veins randomly reticulate; fruit longer than wide, with (4-)5 equal wings |
