| 1 | Leaf blade 3-foliolate |
| 1' | Leaf blade simple, lobed or unlobed |
| 2 | Leaf blade (membranous) coriaceous, unlobed, margin entire, somewhat recurved. [Male bracts small, 5-7 mm long, shifted upwards on the pedicel.] |
| 2' | Leaf blade (except in old stages) generally not coriaceous, unlobed or lobed, margin various, flat |
| 3 | Leaf blade and young stem conspicuously villose |
| 3' | Leaf blade and stem hairy, or scabrous, not villose |
| 4 | Plant mostly annual. Leaf blade membranous. Flowers monoecious, nocturnal and diurnal; corolla small, 20(-30) mm diameter. Bracts of male inflorescences minute, 2 mm long or less, mostly caducous. Probract absent. Seeds compressed with undulate edge. (Fruit much elongated in cultivated var. anguina). |
| 4' | Plant (sub)perennial. Leaf blade generally thicker. Flowers mostly dioecious (sometimes monoecious in T. quinquangulata), nocturnal; corolla 30 mm diameter or more. Bracts of male inflorescences 3 mm long or more, persistent or caducous. Probract present. Seeds tumid or compressed, edge not undulate |
| 5 | Bracts of male inflorescences less than 15 mm long. Seeds tumid (barrel-shaped or (sub)fusiform) (Fig. 91b); fruit ± ellipsoid-fusiform |
| 5' | Bracts of male inflorescences generally much larger. Seeds (rather) compressed, obovate or narrowly elliptic with truncate or cuneate base; fruit ovoid, ellipsoid or globose |
| 6 | Tendrils unbranched. Blade base mostly cuneate at transition to the petiole. Rachis of male inflorescences conspicuously thickened, bracts large, finely hairy. Fruit globose; fruiting pedicel stout |
| 6' | Tendrils 3-5-branched. Blade base cordate. Rachis of male inflorescences thickened or not. Fruit (ob)ovoid or globose; fruiting pedicel generally more slender |
| 7 | Rachis of male (or hermaphroditic) inflorescences conspicuously thickened and set with persistent dark-drying bracts. Leaf blade glabrous, deeply lobed. — Montane |
| 7' | Rachis not thickened. Leaf blade finely hairy beneath and deeply lobed, or glabrous and shallowly lobed. — Lowland or montane |
| 8 | Growing twig tinged reddish at apex. Leaf blade ± scabrid-hairy beneath, lobed to ± halfway or more. Probract narrowly elliptic or linear, entire or ± incised at apex. [Male bracts finely incised. Sepals mostly few-lobed. Fruit ovoid.] |
| 8' | Growing twig green. Leaf blade glabrous (glabrescent) or scabrous, lobed to c. 1/3 deep. Probract (narrowly) ovate |
| 9 | Male bracts incised. Sepals in male flowers (sub)entire. Fruit ovoid. Leaf blade 3-lobed, glands scattered |
| 9' | Male bracts (almost) entire. Sepals in male flowers usually with few slender lobes. Fruit (depressed) globose. Leaf blade 5-angular or shallowly 5-lobed, glands usually several, close to the insertion of the petiole |
