The Rhododendron species collection
The Rhododendron species collections shelter within the pine woods at the northern end of the Arboretum
We present the species according to the Edinburgh classification system, authored largely by James Cullen & David Chamberlain in the late 1970s. It divides the genus into subgenera, sections and subsections.
We usually have several specimens of each species and try to represent different forms and collection numbers if they are available. We place great emphasis on material from documented collections in nature, or cuttings / seeds from hand-pollinated plants of wild origin.
Roughly speaking, one can divide the genus into three main parts (as shown with colour codes in the map of the collections):
Lepidote species, i.e. with leipidote (scale) hairs on the underside of their usually small leaves. They are low-growing mountain plants, often with blue-violet flowers.
The type species, R. ferrugineum, on which Linnaeus based his name is located here.
Elepidote species, i.e. without scale hairs. These are the larger, evergreen shrubs that most people perceive as the actual rhododendrons. They have leaves that are usually hairy on the underside and the flowers are often white or pink.
The so-called 'azaleas'
Mainly deciduous shrubs, most often with flowers in reddish orange or yellow. This group consists of six subgenera, of which we can only present four. They are relatively distantly related to each other and do not constitute a systematic unit as the popular term azalea suggests. About 500 species are found in cultivation, but several of these are not hardy enough to be grown outside here.