| 1 | Pseudo-stipules absent |
| 1' | Pseudo-stipules (a pair of leaflets attached at the base of the petiole) present. |
| 2 | Neither petiole nor rachis winged |
| 2' | Petiole and/or rachis winged |
| 3 | Sepals (sub)glabrous, as long as the petals |
| 3' | Sepals sericeous, shorter than the petals |
| 4 | Midrib angular beneath; nerves up to 1 cm apart. Inflorescences solitary, simple, up to 5.5 cm long |
| 4' | Midrib rounded beneath, nerves at least 1 cm apart. Inflorescences either solitary and widely branched, or simple and fascicled, up to 60 cm long |
| 5 | Fruits distinctly lobed, lobes spreading, subglabrous |
| 5' | Fruits not or slightly, rarely distinctly lobed, lobes erect, densely hairy |
| 6 | Inflorescences axillary, sometimes together pseudoterminal, up to 5 cm long, hardly branched. Ovary subglabrous |
| 6' | Inflorescences terminal and in the upper leaf axils, 25-50 cm long, widely branched. Ovary densely hairy |
| 7 | Leaflets mostly with glandular-pitted warts. Petal scales not crested. Dry fruit coarsely wrinkled |
| 7' | Leaflets without glandular-pitted warts. Petal scales mostly crested. Dry fruit smooth |
| 8 | Leaves more than 3-jugate. Fruits hardly lobed |
| 8' | Leaves (l-)2(-3)-jugate. Fruits distinctly lobed |
| 9 | Petiole and rachis winged |
| 9' | Petiole never, rachis very rarely winged |
| 10 | Ovary 3- (or 4-)celled. Twigs and leaves glabrous. Leaflets narrow, usually 4-7 times as long as wide, rarely more than 20 by 4 cm, base acute or sometimes rounded |
| 10' | Ovary 2-celled. Twigs and leaves sparsely hairy. Leaflets broader, 3-5 times as long as wide, up to 33 by 10.5 cm, base cordate |
| 11 | Fruits distinctly lobed, lobes spreading. |
| 11' | Fruits not or slightly, rarely distinctly lobed, lobes ± erect |
| 12 | Leaves imparipinnate. Fruits 3-lobed |
| 12' | Leaves paripinnate. Fruits nearly always 2-lobed |
| 13 | Leaves 7-14-jugate. Twigs up to 1 cm in diam., tomentose. |
| 13' | Leaves (15-)30-40-jugate. Twigs 1.5-2 cm in diam., glabrous. |
| 14 | Leaflets with pitted warts looking like small white scales. Leaves mostly imparipinnate, (3-)7-42-jugate. Inflorescences terminal and axillary |
| 14' | Leaflets densely finely pitted underneath. Leaves paripinnate or with a reduced terminal leaflet, 1-8(-14)-jugate. Inflorescences rarely terminal |
| 15 | Nervation open |
| 15' | Nervation closed |
| 16 | Inflorescence and sepals densely hairy |
| 16' | Inflorescence and sepals glabrous |
