| 1 | Inflorescence a thyrse (most dichasia simple or compound); leaf rachis usually winged or margined |
| 1' | Inflorescence a panicle or a raceme (all dichasia reduced to a single flower); leaf rachis unwinged |
| 2 | Petals puberulent to sparsely wooly; disc cup-shaped, 5-lobed |
| 2' | Petals glabrous; disc annular |
