Rhododendron uniflorum

This is mentioned in the main work on page 740, under R. pemakoense, horticulturally a much more important species. Although not the oldest member of the subsect. Uniflora (R. pumilum dates from 1849), its name was used when Cowan and Davidian set up the Uniflorum series in 1948, and it consequently became the type of the subsection based on it. This is a pity, since R. pumilum is the only widespread species in the subsection. Curiously enough, the other five species that have been described are known from only seven gatherings in the wild, from the region of the Tsangpo Bend in south-east Tibet to north-west Burma, and from cultivated plants derived from them. These five are reduced to three in the Edinburgh revision: R. uniflorum, with var. imperator; R. pemakoense (including R. patulum in synonymy); and R. ludlowii. In view of the paucity of wild material, the treatment in the Edinburgh revision is ‘purely provisional’ (Rev. 1, p. 120).