| 1 | Ostiole tri-radiate or slit-shaped, the upper ostiolar bracts descending |
| 1' | Ostiole circular, the upper ostiolar bracts horizontal |
| 2 | Stipules connate |
| 2' | Stipules free |
| 3 | Internodes conspicuously different in length, the proximal ones of a season’s growth long, subsequently shorter, the ultimate ones very short, sometimes with persistent stipules forming terminal buds |
| 3' | Internodes not conspicuously different in length |
