| 1 | Trailing or scandent shrub with large fleshy tubers underground. Leaflets 8-11 pairs per pinna, opposite, 1.1-1.9 by 0.4-0.75 cm |
| 1' | Giant climbers, without fleshy tubers. Leaflets to 7 pairs per pinna, opposite or alternate, leaflets at least 1.4-4 by 0.7-1.8 cm |
| 2 | All leaflets except the distal pair alternate |
| 2' | Leaflets all opposite |
| 3 | Apex of leaflets rounded to truncate, emarginate, most often glaucous beneath. Pods spirally twisted. Seeds irregularly compressed |
| 3' | Apex of leaflets ± acuminate to obtuse, ± emarginate to bifid, not or but very rarely glaucous beneath. Pods straight or slightly curved. Seeds flat, subcircular |
| 4 | Leaflets 1 (or 2) pair(s) per pinna. Pod with a parchment-like endocarp |
| 4' | Leaflets 3 or 4 (or 5) pairs per pinna. Pod with a woody endocarp. |
