Right. The centers of diversity are in the Himalayas and Malaysia, but elsewhere native species can have some surprising locations: Greenland, for one. Who knew?benhall.1 wrote:The ones that cause such a problem in Snowdonia, North Wales, are an invasive, non-native, Asian species. I had thought that they were all from Asia, but apparently not.
I looked up the Pontic rhododendron, and according to Wikipedia - cue grain of salt - it's not just native to Asia, but southern Europe as well. It's possible that some of your invasive clusters could have hailed from there, too.