| 1 | Leaves in distal parts of shoots all opposite; basal leaves often alternate |
| 1' | Leaves alternate, rarely some leaves (sub)opposite |
| 2 | Inflorescence peduncled |
| 2' | Inflorescence sessile |
| 3 | Thecae with an appendix (excluding the outgrowth of the connectivum) |
| 3' | Thecae without an appendix (excluding the outgrowth of the connectivum) |
| 4 | Ridge separating the thecae irregularly undulate and fleshy |
| 4' | Ridge separating the thecae smooth and thin |
