| 1 | Leaves opposite or clearly predominantly so; petals usually present |
| 1' | Leaves spiral or alternate; petals absent |
| 2 | Mangrove shrub or tree with stilt-roots and often pneumatophores; flowers with pair of small prophylls (bracteoles) fused to lower hypanthium |
| 2' | Woody lianas, shrubs or small trees, without stilt-roots and pneumatophores; flowers without prophylls (bracteoles) fused to lower hypanthium |
| 3 | Flowers in small dense spherical inflorescences; fruits densely packed into cone-like heads |
| 3' | Individual flowers clearly visible; fruits not in cone-like heads |
| 4 | Calyx lobes clearly demarcated; anthers dorsifixed and versatile |
| 4' | Calyx lobes scarcely developed; anthers adnate to filament |
