Rhododendron - An Introduction
Rhododendrons are well known in Europe for more than 300 years. Certainly they rank among the most beautiful flowering shrubs. The genus Rhododendron containing the most describes species worldwide belongs to the Ericaceae family. There are about 1000 exactly separable species, even 150 species more are described. Rhododendron hirsutum, Rh. ferrugineum and Rh. palustre ssp. palustre are indigenous in Germany; seven more are in Europe. Main dispersal area is Asia: 525 species in Yunnan, Szechuan and Japan; 25 species in North America in coastal areas and in the Rocky Mountains; 330 species in Malaysia, those are species of the subgenus Vireya which are not suitable for european climate; last not least two species in Australia (Rh. lochiae and Rh. notiale). There are no Rhododendrons in Africa, South- and Centralamerica.
There are different attempts to systematize the genus Rhododendron e.g. from Sleumer and Seithe, by Spethmann, by Goetsch, Eckert, Hall and by Chamberlain et al. Garden Hybrids are usually organized into the following rhododendron groups:
Please take a look at the following:
Genaue Beschreibungen und eine Vielzahl von Fotos zu allen Arten und allen in Deutschland vorkommenden Sorten von Rhododendron finden sich auf den Seiten der Deutschen Genbank Rhododendron (Homepage der Landwirtschaftskammer Niedersachsen).