| 1 | Inflorescences involucrate with relatively large basally attached bracts at the base of the globose receptacle, or bracts at the margin of the turbinate to discoid receptacle; staminate flowers usually with 2 stamens |
| 1' | Inflorescences without subtending bracts; staminate flowers with one stamen |
| 2 | Stipules free, linear, subpersistent |
| 2' | Stipules fused, broader, caducous |
| 3 | Trees dioecious; pistillate flowers free |
| 3' | Trees monoecious; pistillate flowers connate |
