A member of the botanical family Ericaceae, the genus Rhododendron is currently home to over 900 species, ranging from the magnificent Rhododendron rex of western China, with leaves up to 37cm in length, to the miniature Rhododendron caespitosum from New Guinea, whose leaves do not exceed 0.6cm. To bring order to such a large number of diverse species, a botanical hierarchy is used to divide the genus into smaller botanical units and sub-units based on similarities in morphological characteristics.

At the top of the Rhododendron hierarchy is the rank of Genus and this is divided into nine Subgenera, one of which contains a group of over 300 species from south-east Asia known collectively as Subgenus Vireya.

As can be seen from the diagram below, Subgenus Vireya is sub-divided into seven Sections, with one of these Sections further refined into five Subsections.