1 | All leaves opposite. |
1' | All leaves alternate or some of the leaves opposite. |
2 | Inflorescences branched. |
2' | Inflorescences unbranched and sessile. |
3 | Herbs. |
3' | Treelets, shrubs or subshrubs. |
4 | Pistillate flower with a perianth. |
4' | Pistillate flowers without perianth. |