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Article from Bean's Trees and Shrubs Hardy in the British Isles
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'Rhododendron roxieanum' from the website Trees and Shrubs Online (treesandshrubsonline.
Shrub, sometimes dwarf, 0.15-2.5(-4) m. Leaves 5-12 x 0.6-4 cm, apex acute to cucullate, margins strongly recurved, lower surface covered with a thick two-layered indumentum, the upper layer rufous, loose, lanate-tomentose, composed of ramiform hairs, the lower radiate, compacted; petioles rufous-tomentose to glabrescent. Flowers 6-15, in tight truss; calyx 0.5-2 mm; corolla white to (rarely) pale yellow, sometimes flushed with pink, with purple flecks, funnel-campanulate, nectar pouches lacking; ovary densely rufous-tomentose and/or glandular, style glabrous. Flowering April-May. Royal Horticultural Society (1997)
Distribution China SE Tibet, NW Yunnan, SW Sichuan
Habitat 3,050-4,250 m
RHS Hardiness Rating H5
Conservation status Least concern (LC)
Taxonomic note R. roxieanum hybridizes in the wild with R. proteoides and probably also with several other species, thus blurring the distinctions between the taxa. Var. oreonastes is a marked form with short, extremely narrow leaves. The variable var. cucullatum is morphologically intermediate between var. roxieanum and R. proteoides and is probably of hybrid origin. R. aganniphum, R. alutaceum and perhaps R. phaeochrysum may also be involved as parents in this hybrid complex. Royal Horticultural Society (1997)
A small evergreen shrub, usually under 6 ft high in the wild, but occasionally tree-like and up to 15 ft high; young shoots clothed with reddish-brown wool; inner bud-scales persisting on the branchlets for several years. Leaves linear, linear-oblong, or narrow-oblanceolate, 13⁄4 to 43⁄4 in. long, rarely over 1 in. wide and usually much less, pointed (more rarely blunt) at the apex, narrowed at the base to a stout petiole, which is tomentose like the young stems, upper surface of blade dark green, dull or glossy, midrib grooved, underside thickly covered with a reddish-brown or sometimes paler-coloured tomentum, concealing the raised midrib, margins usually recurved. Flowers ten to twenty in a tight terminal truss, opening in May; pedicels tomentose, with or without glands. Calyx very small, glandular and usually downy also. Corolla funnel-shaped to campanulate, 11⁄4 to 11⁄2 in. long, white or white flushed with pink or cream-coloured, with or without crimson spots. Stamens ten, hairy in the lower part. Ovary tomentose, with or without glands; style hairy at the base. Bot. Mag., t. 9383. (s. Taliense ss. Roxieanum)
A native of alpine and subalpine moorland or tree-line coniferous forest, from S.W. Szechwan through the bleaker parts of N.W. Yunnan to S.E. Tibet; discovered by Forrest in 1912 and introduced by him. It is a variable species, especially in habit and relative width of leaf, but curiously enough the taller forms are not broader-leaved as might be expected. Rock’s 59205 was described by him as a small tree 10 ft high but with linear, almost needle-shaped leaves. R. roxieanum is slow-growing, and also slow to reach the flowering state, but makes an interesting specimen.
[var. oreonastes] – This, not surprisingly, has been included in the typical part of R. roxieanum. If an Oreonastes group is to be recognised under the new provision of the Cultivar Code, it should perhaps be restricted to plants that are both narrow-leaved and of dwarf habit.
var. cucullatum (Hand.-Mazz.) Chamberlain R. cucullatum Hand.-Mazz. – To Handel-Mazzetti’s indignation, his species was sunk in R. roxieanum by Dr Hutchinson, but it has now been revived as a variety, differing essentially only in its broader leaves. There is, however, no sharp cut-off between it and var. roxieanum. It was recently collected in the Tali range (Cangshan) by the Sino-British Expedition of 1981, where it apparently intergrades with R. taliense (Cox, Rhododendrons 1981-2, p. 7; The Smaller Rhododendrons, p. 186)
R. recurvoides – This has now been transferred to subsect. Glischra.
Leaves elliptic, 2.2–4× as long as broad; ovary and pedicels glandular and/or tomentose.
Synonyms
R. recurvum var. oreonastes Balf. f. & Forr
Leaves linear, 8–15× as long as broad; ovary and pedicels glandular. Royal Horticultural Society (1997)
Awards
AM 1973 (Crown Estate Commissioners, Windsor); flowers white, corolla lobes tipped red-purple, with darker spots in throat. AGM 1993
RHS Hardiness Rating: H5
Leaves linear, less than {1/4} in. wide. Described from a plant only 2 ft high found by Forrest on the Kari La, Mekong-Yangtse divide, at 14,000 ft. It is not a very distinct variety, since taller forms may have very narrow leaves also (see above) and comparatively dwarf forms may have leaves of the normal width. Award of Merit May 1, 1973, when exhibited by the Crown Estate Commissioners, Windsor Great Park.
Either a synonym of R. proteoides or a hybrid of it (see under R. proteoides).
Leaves linear, 4-8× as long as broad; ovary and pedicels tomentose, with or without glands.
Taxonomic note (incl. R. recurvum Balf.f. & Forrest)