key morphological characteristics. These included the position of the inflorescence buds (terminal or lateral), whether lepidote or elepidote, deciduousness of leaves, and whether new foliage was derived from axils from previous year's shoots or the lowest scaly leaves (Table 2.). Following the cladistic analysis of Goetsch et al. (2005) this scheme was simplified, based on the discovery of three major clades (A, B, C) as follows. Clade A Subgenus Rhododendron : Small leaf or lepidotes (scales on the underside of the leaves). 3 sections, about 400 species, type species: Rhododendron ferrugineum. Subgenus Choniastrum : 11 species Clade B Subgenus Hymenanthes : Large leaf or elepidotes (without scales), including deciduous azaleas. 2 sections, about 140–225 species, type Rhododendron degronianum. Clade C Subgenus Azaleastrum : Evergreen azaleas. 3 sections, about 120 species, type Rhododendron ovatum. Sister taxon Subgenus Therorhodion : 2 species (Rhododendron camtschaticum, Rhododendron redowskianun). Sections and subsections The larger subgenera are further subdivided into sections and subsections Some subgenera contain only a single section, and some sections only a single subsection. Shown here is the traditional classification, with species number after Chamberlain (1996), but this scheme is undergoing constant revision. Revisions by Goetsch et al. (2005) and by Craven et al. (2008) shown in (parenthetical italics). Older ranks such as Series (groups of species) are no longer used but may be found in the literature, but the American Rhododendron Society still uses a similar device, called Alliances Subgenus Rhododendron L. (3 sections, 462 species: increased to five sections in 2008) (Discovereya (Sleumer) Argent, raised from Vireya) Pogonathum Aitch. & Hemsl. (13 species; Himalaya and adjacent mountains) (Pseudovireya (C.B.Clarke) Argent, raised from Vireya) Rhododendron L. (149 species in 25 subsections; temperate to subarctic Northern Hemisphere) Vireya (Blume) Copel.f. (300 species in 2 subsections; tropical southeast Asia, Australasia. At one time considered separate subgenus) Subgenus Hymenanthes (Blume) K.Koch (1 section, 224 species) (Increased to two sections) Ponticum (24 subsections) (Pentanthera (2 subsections – new section, moved from subgenus Pentanthera) Subgenus Pentanthera (4 sections, 23 species) (Discontinued) Pentanthera (2 subsections – moved to subgenus Hymenanthes) Rhodora (L.) G. Don (2 species; Rhododendron canadense, Rhododendron vaseyi) (Discontinued, redistributed) Sciadorhodion Rehder & Wilson (4 species) (Moved to subgenus Azaleastrum) Viscidula Matsum. & Nakai (1 species; Rhododendron nipponicum) (Discontinued, added to section Tsutsusi, subgenus Azaleastrum) Subgenus Tsutsusi (Sweet) Pojarkova (2 sections, 80 species) (Discontinued, reduced to section and moved to subgenus Azaleastrum) Brachycalyx Sweet (3 alliances,