Dwarf prostrate shrub, the ends of the branches ascending to 0.5 m; young growth scaly. Leaves 1.3-2.5 x 0.5-1 cm, oblong-elliptic, apex acute or rounded, margin entire, lower surface with very distant scales that are equal, golden at first, soon turning brown, and have narrow rims. Flowers 1-2, in a terminal inflorescence; calyx lobes oblong, 1.5-2.5 mm; corolla purple, funnel-campanulate, 21-25 mm, tube 12-14 mm, outer surface densely pilose, sparsely scaly; stamens 10; ovary scaly, impressed below the declinate style that is glabrous and longer than the stamens. Flowering April-May. Royal Horticultural Society (1997)
Distribution Myanmar NE China SE Tibet
Habitat 3,050-3,650 m
RHS Hardiness Rating H4
Conservation status Near threatened (NT)
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).
R. imperator Kingdon-Ward
Leaf apex acute. Royal Horticultural Society (1997)
AM 1934 (Lord Swaythling, Townhill Park, Southampton) as R. imperator, from Kingdon-Ward 6884; flowers rosy purple.
RHS Hardiness Rating: H4
Leaf apex rounded.