| 1 | Leaf blade (2-)3-5-foliolate (in T. celebica and T. wawrae blades occasionally simple) |
| 1' | Leaf blade simple, lobed or unlobed |
| 2 | Probract chartaceous, ± flat. Texture of leaf blade various. Fruit 10 cm long or less, when fruit larger, then exocarp woody |
| 2' | Probract thick, ± concave. Leaf blade chartaceous or coriaceous. Fruit (narrowly) elliptic, (9-)10 cm long or more |
| 3 | Seeds ± ovate, 15-21 by 8-14 mm. — Sumatra, Peninsular Malaysia, Borneo, Java |
| 3' | Seeds narrower, (narrowly) elliptic, 9-17 by 3-6 mm |
| 4 | Fruiting pedicel 5-7 cm long; seeds elliptic, 9-10 by 4-4.5 mm. — Sulawesi, Moluccas |
| 4' | Fruiting pedicel 1-1.5 cm long; seeds (narrowly) obovate, 11-16 by 6-10 mm. — Flores |
| 5 | Probract with glands. Exocarp leathery. Seeds 16-20 mm long. — West Malesia |
| 5' | Probract without glands. Exocarp woody. Seeds 20-27 mm long. — Moluccas, New Guinea |
| 6 | Plant (sub)annual; monoecious; diurnal. [Male bracts 1(-2) mm long, caducous.] Corolla 20(-30) mm diam. or less. Seeds thickish, compressed, with coarsely sinuate (undulate) edge. [Fruit small, or very much elongated in cultivated var. anguina.] — Widespread |
| 6' | Plant (sub)perennial; monoecious or dioecious; largely nocturnal. Corolla 30 mm diam. or more. Seeds either tumid, with median belt, or seeds compressed with edge smooth or ± crenulate (sometimes ± truncate or notched at one or both ends) |
| 7 | Seeds tumid (i.e. as if 3-parted, with the embryo in the middle) |
| 7' | Seeds compressed |
| 8 | Seeds fusiform (barrel-shaped), lateral sides ± conical (Fig. 91b). — Widespread |
| 8' | Seeds butterfly-like, with inflated sides |
| 9 | Stem angular. [Leaf blade scabrous, apex cuspidate. Seeds 10-12 by 17-20 by c. 5 mm.] — Sabah |
| 9' | Stem terete |
| 10 | Apex of leaf blade (obtuse or) acute-acuminate, often with a short mucro. Seeds 6-10 by 7-12 by 2-3 mm. — Sumatra, Borneo |
| 10' | Apex of leaf blade acute-acuminate, with a 13-20(-25) mm long acumen. Seeds c. 10 by 18 by 4 mm. — Sabah |
| 11 | Seeds subcircular, with broad margin, radiately striate or not. Leaf blade unlobed |
| 11' | Seeds (ob)ovate or (narrowly) elliptic, margin narrower or absent. Leaf blade lobed or unlobed |
| 12 | Leaf blade subcircular in outline, auricles absent. — Sumatra |
| 12' | Leaf blade (narrowly) ovate in outline, with at transition to petiole 2 gland-bearing bulges or auricles. — Borneo |
| 13 | Fruiting among or close to the leaves |
| 13' | Fruiting far below the leaves |
| 14 | Seeds notched or undulate-truncate at one or two ends |
| 14' | Seeds neither notched nor undulate-truncate |
| 15 | Fruiting pedicel 2-coloured (with a smooth portion to the fruit). Seeds embedded in green-black pulp. — North Sumatra, Peninsular Malaysia |
| 15' | Fruiting pedicel evenly coloured; seeds embedded in white or pink pulp (fruit of T. pulleana not known). — New Guinea [sect. Edulis] |
| 16 | Leaf blade unlobed, subcoriaceous, ± hastate, mostly with some spines towards the base |
| 16' | Leaf blade unlobed or lobed, ± membranous, chartaceous or (sub)coriaceous, margin not spiny |
| 17 | Seeds with cuneate (acute) base, margin faint. Leaf blade unlobed, margin entire. Fruit with exocarp longitudinally grooved, ± woody, smooth. — Papua New Guinea (Woodlark Is., Bougainville Is.) |
| 17' | Seeds truncate, without margin. Leaf blade lobed or unlobed. Fruit with exocarp leathery, drying ± winkled. |
| 18 | Seeds subtriangular, at apex much broader than at base |
| 18' | Seeds narrowly elliptic, ± parallel-sided, ± equally broad at both ends (resembling seeds of the genus Lagenaria) |
| 19 | Fruit smooth on drying; fruiting pedicel 1.5-2.5 cm long, 2-3 mm thick. Seeds 8-10 mm long. [Male rachis not thickened; bracts dentate.] |
| 19' | Fruit rough on drying; fruiting pedicel c. 3 cm long, 3 mm thick, finely brown-hairy. Seeds 10-13 mm long. [Male rachis thickened; bracts (sub)entire.] |
| 20 | Leaf blade chartaceous or coriaceous, glabrous. Fruiting pedicel 3-10 cm long |
| 20' | Leaf blade membranous or chartaceous, rough hairy on upper surface. Fruiting pedicel 1.5-3 cm long |
| 21 | Seeds at base chisel-shaped pointed |
| 21' | Seeds not pointed (base rounded or truncate) |
| 22 | Leaf blade broadly ovate in outline, unlobed, but margin coarsely dentate. Blade glands large, 2-5 mm diameter |
| 22' | Leaf blade subcircular in outline, 5(-7)-angular or shallowly lobed. Blade glands small, c. 1 mm diam. or absent |
| 23 | Stem sharply angular; young shoots reddish. Leaf blade brown or greenish on drying. Fruit ripening orange, paler speckled. — Sabah |
| 23' | Stem grooved; young shoots green. Leaf blade blackish on drying. Fruit ripening evenly red. — Widespread |
| 24 | Seeds, at least partly, (8-)10 mm wide or more |
| 24' | Seeds less than (8-)10 mm wide |
| 25 | Plant villose all over. Fruit pulp white. Tendril 3-9-branched |
| 25' | Plant subglabrous. Fruit pulp green-black. Tendril 2- or 3-branched |
| 26 | Leaf blade sometimes simple, shallowly or deeply lobed (usually 3-5-foliolate). Fruit ovoid, evenly orange-red or yellow-striped; pericarp c. 5 mm thick |
| 26' | Leaf blade 3-5-lobed. Fruit globose, whitish green-striped or not; pericarp 10-18 mm thick. — North Sumatra |
| 27 | Seeds (13-)15-21(-25) mm long |
| 27' | Seeds less than 15 mm long |
| 28 | Fruiting pedicel 2-coloured, with a smooth part at the side of the fruit, the remaining part grooved |
| 28' | Fruiting pedicel evenly coloured and smooth overall |
| 29 | Fruiting pedicel 3-5 mm thick. Leaf blade drying dull, ± scabrous |
| 29' | Fruiting pedicel 10 mm thick or more. Leaf blade not scabrous |
| 30 | Fruit globose |
| 30' | Fruit ovoid |
| 31 | Tendril simple. Blade base at transition to petiole ± cuneate |
| 31' | Tendril 2-4-branched |
| 32 | Seeds ± rounded at both ends, 17-18 by 5-6 mm |
| 32' | Seeds subtruncate at base |
| 33 | Leaf blade deeply (3-)5-lobed (in juvenile stages entire). — Sumatra, Borneo, Java |
| 33' | Leaf blade entire or 3-lobed |
| 34 | Fruit ellipsoid, c. 5 cm long, fruiting pedicel c. 2 cm long. — Sarawak, Philippines |
| 34' | Fruit subglobose, 10-13 cm long, fruiting pedicel c. 4 cm long. — Sabah |
| 35 | Leaf blade unlobed, ± coriaceous, margin recurved. — Central & South Sumatra and West Java |
| 35' | Leaf blade lobed (or unlobed), chartaceous or (sub)coriaceous, margin flat |
| 36 | Leaf blade reddish brown on drying. Probract narrowly elliptic or linear, 10-20 by c. 2 mm |
| 36' | Leaf blade green-brown on drying. Probract (ob)ovate-elliptic, 3-15 by 4-8 mm |
| 37 | Fruit ovoid-ellipsoid; seeds 1-2 mm thick |
| 37' | Fruit subglobose; seeds 3-4 mm thick |
| 38 | Fruit more than 10 cm long. — Sulawesi, Timor, Philippines, Moluccas |
| 38' | Fruit (much) less than 10 cm long |
| 39 | Fruiting pedicel 5-7 cm long. [Leaf blade simple, but usually 5-foliolate.] — Sulawesi, Moluccas |
| 39' | Fruiting pedicel 1.5-2.5 cm long |
| 40 | Fruit ripening (possibly) green. — Borneo, Philippines; peat swamp forest |
| 40' | Fruit ripening red |
| 41 | Fruit broadly ovoid, 6-7 cm long; dry pericarp 10-15 mm thick; fruiting pedicel c. 2 mm thick. Leaf blade green on drying, margin usually conspicuously dentate. — Philippines |
| 41' | Fruit (narrowly) ovoid, 7-9 cm long; dry pericarp 5-10 mm thick; fruiting pedicel 3-9 mm thick. Leaf blade (green-)brown on drying, margin usually entire or shallowly dentate (dentate in Sulawesi). — Widespread, not in the Philippines |
