| 1 | Leaves with only one pair of opposite leaflets |
| 1' | Leaves with 2 to many pairs of opposite to alternate leaflets (sometimes only one pair of leaflets also present) |
| 2 | Abaxial surface of leaflets minutely furfuraceous (covered with peltate scales) |
| 2' | Abaxial surface of leaflets glabrous or variously pubescent but without scales |
| 3 | Leaflets emarginate or sometimes rounded at apex, stiff and brittle. |
| 3' | Leaflets acute, acuminate, caudate, obtuse, or obtusely acuminate at apex (sometimes obtuse and then retuse or emarginate in same plant), chartaceous or coriaceous |
| 4 | Capsules globose, woody, usually verrucose |
| 4' | Capsules lobed or turbinate, coriaceous or slightly woody, smooth or verrucose |
| 5 | Leaflets chartaceous, dull, drying brownish and somewhat wrinkled, tertiary veins finely reticulate, conspicuously of lighter color, domatia usually absent, the base asymmetrical, obtuse/rounded |
| 5' | Leaflets subcoriaceous, slightly shiny on adaxial surface, drying greenish or greenish brown, flat, tertiary veins loosely reticulate and rather inconspicuous, with one or two domatia on the lowest secondary vein axis, the base slightly asymmetrical, acute sometimes obtuse |
| 6 | Capsules turbinate |
| 6' | Capsules bilobed or trilobed |
| 7 | Leaflets 8-16 per leaf, oblong, abruptly long- acuminate or caudate at apex |
| 7' | Leaflets (2) 4-7 per leaf, ovate, elliptic, or obovate, obtuse, rounded, or acuminate at apex |
| 8 | Leaflet with tertiary reticulate venation; flowers solitary (dichasia reduced to a single flower along inflorescence axis) or in depauperate simple dichasia |
| 8' | Leaflets with tertiary subclathrate venation; flowers in simple dichasia |
| 9 | Capsules verrucose, asymmetrically bicoccate |
| 9' | Capsules smooth, usually symmetrically bicoccate or tricoccate |
| 10 | Fruits tricoccate; leaflets obtuse or rounded at apex |
| 10' | Fruits bicoccate; leaflets obtuse, obtusely acuminate, acuminate or caudate at apex |
