| 1 | Leaflets obovate (to elliptic), apex rounded or emarginate. Peat swamp forests. . |
| 1' | Leaflets lanceolate, ovate (or elliptic), apex ± acuminate. Other habitats |
| 2 | Leaflets glabrous, lanceolate (or elliptic), base obtuse to rounded. — Borneo, river banks |
| 2' | Leaflets pubescent to subglabrous (or glabrous), ovate, base cuneate to rounded |
| 3 | Leaflets long acuminate (acumen to 24 mm), base cuneate. — Borneo |
| 3' | Leaflets acute to acuminate (acumen never more than 15 mm), base rounded, ob- tuse to acute (or subcuneate) 4\ |
| 4 | Calyx 4–4.5 mm long, dark brown; petals glabrous; staminal tube with 5 erose lobes; petiolule of apical leaflet 4-10 cm. — Borneo |
| 4' | Calyx c. 3.5 mm, yellow-green; petals ± pubescent; staminal tube with 10 bifid lobes; petiolule of apical leaflet 3–5.5 cm |
