| 1 | Leaves glandular-dotted beneath. Stipules peltately attached |
| 1' | Leaves not glandular-dotted. Stipules not peltate. |
| 2 | Leaves in whorls of 3. Stipules interpetiolar |
| 2' | Leaves spiral. Stipules not interpetiolar. |
| 3 | Leaves not crowded near the end of the twigs. Terminal buds not conferted, scales imbricate or rarely with a tendency to distichy. |
| 3' | Leaves crowded at the end of the branchlets. Terminal buds conferted, scales with a tendency to orthostichy |
| 4 | Wood-rays (of older branches and mature wood) exclusively uniseriate. |
| 4' | Wood-rays uniseriate and many-celled |
