| 1 | Leaflets with symmetric base; petiolules grooved or the margins incurved above. Petals obovate to oblanceolate, oblong, or narrowly oblong, 3-8 by 1-2 mm. Anthers dorsifixed. |
| 1' | Leaflets usually with asymmetric or oblique base; petiolules, if present, flat or convex above. Petals broadly ovate, ovate-oblong, or elliptic to elliptic-oblong, 3-5 by 1½-3 mm. Anthers dorso-basifixed. |
| 2 | Leaflets 4-12 pairs, coriaceous, nerves 14-20 pairs. |
| 3 | Stamens inserted in the grooves at the lower half of the disk |
| 3' | Stamens inserted at the base of the disk |
| 3'' | Leaflets usually 2-3 pairs, thin-coriaceous, nerves 9-11 pairs |
| 4 | Flowers distinctly pedicelled, pedicels 2-5(-7) mm. Calyx lobes ⅔ or more the length of the calyx |
| 4' | Flowers subsessile. Calyx lobes c. ⅓ the length of the calyx |
