| 1 | Petiole 2-3 mm. Leaf margins slightly glandular-serrate. Primary branches of the inflorescence sub-4-whorled. Stamens (15-)20. Ovules and seeds with a suprahilar arillode, without a basal wing. 1. Sect. Brewstera |
| 1' | Petioles 10-25 mm. Leaf margins entire, eglandular. Primary branches of the inflorescence paired. Stamens 10. Seeds with a basal wing, suprahilar arillode absent. Sect. Ixonanthes. |
| 2 | Inflorescence dense. Flowers at anthesis 1.5-3 by 1-2.5 mm diam. Style 1.5-2.5 mm. Fruit at most 1.5(-2) cm long. Valves ultimately apically 1-2 mm deep bifid. Seeds 10-13 by 3-4 mm 2. Section Ixonanthes |
| 2' | Inflorescence lax. Flowers at anthesis 3-5 by 2-7 mm. Style 15-20 mm. Fruit (2-)3-4(-4.5) cm long. Valves not bifid. Seed 18-20 by 4-9 mm 2. Section Ixonanthes |
