This is one of those genera that has been the center of discussion by taxonomists. That is why the number of species is estimated to be between 150 to about 450 which is quite a range. Species are being transferred to other genera as we speak, I would guess. It is native to the tropical regions with some species also coming from the temperate regions of the world. Most are shrubs, vines or small trees.

Note: Some resources list these plants as having the genus name, Clerodendron.