Kindly sponsored by
Peter Norris, enabling the use of The Rhododendron Handbook 1998
Article from Bean's Trees and Shrubs Hardy in the British Isles
'Rhododendron sperabile' from the website Trees and Shrubs Online (treesandshrubsonline.
Shrub, 1–2 m. Leaves 5–9.5 × 1–2.6 cm, elliptic, sometimes narrowly so; lower surface covered with a dense but loose continuous whitish to cinnamon indumentum composed of ramiform hairs, also with glandular setae overlying the midrib, epidermis glaucous-papillate; petioles densely tomentose, with some glandular setae. Flowers 4–5, in a dense truss; calyx 2–3 mm, coloured; corolla fleshy, crimson, tubular-campanulate, 35–40 mm; ovary densely rufous-tomentose and stalked-glandular, tapering into the glabrous style. Flowering April-May. Royal Horticultural Society (1997).
Distribution Myanmar NE China NW Yunnan
Habitat 3,000–3,650 m
RHS Hardiness Rating H4
Conservation status Vulnerable (VU)
An evergreen shrub 3 to 9 ft high of stiff habit; young shoots clothed with loose and (at first) white wool and glandular bristles. Leaves lanceolate or narrowly elliptic, sharply pointed, 2 to 4 in. long, 1⁄2 to 11⁄4 in wide, dark green and becoming glabrous above, covered beneath with a thick loose wool which is at first dull white, later reddish brown, and persists till the leaf falls; stalk 1⁄4 to 1⁄2 in. long, woolly and glandular like the young shoot. Flowers in a terminal hemispherical truss 3 in. wide, opening in May. Calyx small, shallowly five-lobed, glandular; flower-stalk 5⁄8 in. long, woolly and glandular. Corolla bell-shaped, clear scarlet, about 11⁄2 in. long and wide, five-lobed. Stamens ten, 1 to 11⁄2 in. long, glabrous. Ovary slender, tapered, thickly clothed like the lower part of the style with glandular hairs. Bot. Mag., t. 9301. (s. and ss. Neriiflorum)
R. sperabile was discovered by Farrer and Cox in 1919, growing at 10,000 ft in a ravine below the Hpimaw pass in north-east Upper Burma and was introduced by them (Farrer 888); later sendings by Forrest were from the same area. According to the collectors’ field notes it varies in the colour of its flowers from scarlet-crimson to deep crimson, and also in habit, from compact to leggy, but is always comparatively dwarf, and this is also true of cultivated plants, which are normally less than 6 ft high.
R. sperabile is hardy in the woodland gardens of Sussex and flowers freely. It is not so fine a species as R. neriiflorum, but the dwarfest and most compact forms deserve to be propagated. It received an Award of Merit when shown by Lionel de Rothschild, Exbury, on May 5, 1925 (from Farrer 888).
A vigorous and tall-growing form of R. sperabile was introduced by Kingdon Ward in 1926 from the Di Chu valley on the borders between Assam, Tibet, and Burma (KW 7124).
Leaf indumentum cinnamon when mature; leaves 2.5-3.5× as long as broad.
Awards AM 1925 (L. de Rothschild, Exbury) from Farrer 888; flowers scarlet.
Leaf indumentum whitish when mature; leaves 3–4(–8)x as long as broad. Royal Horticultural Society (1997).
AM 1985 (R.N.S. Clarke, Borde Hill) to a clone 'Rouge et Noir', from Kingdon-Ward 7124; trusses loose, up to 11 flowers, corolla deep crimson, with darker spotting in throat.
Taxonomic note This species is allied to R. sperabiloides (q.v.) and to R. floccigerum; from the latter it differs in its thicker, more persistent leaf indumentum. Royal Horticultural Society (1997).
Leaves relatively narrower, less lanceolate, sometimes elongate elliptic, with a paler and thinner indumentum. Introduced by Forrest from the Mekong-Salween divide west of Weihsi. It grows taller than the typical form and is of rather sparse habit. The name var. chimiliense was given to Forrest’s 26478, from the Chimi-li pass on the Nmai-Salween divide, but the name was apparently never published. In some of the cultivated plants from this batch of seed the leaves are almost glabrous beneath.