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Peter Norris, enabling the use of The Rhododendron Handbook 1998
Article from Bean's Trees and Shrubs Hardy in the British Isles
'Rhododendron campanulatum' from the website Trees and Shrubs Online (treesandshrubsonline.
Dwarf shrub to a small tree, 0.5–4.5 m. Leaves 7–14 × 3.8–7.5 cm, ovate to broadly elliptic, upper surface glabrous, with a dense fulvous lanate tomentum composed of capitellate to ramiform hairs. Flowers 8–15 in a truss, white to pale mauve or deep plum purple, with purple flecks, open-campanulate, nectar pouches lacking, 30–50 mm; ovary and style glabrous. Flowering April-May. Royal Horticultural Society (1997).
Distribution Bhutan India Kashmir to Sikkim Nepal
Habitat 2,700–4,500 m
RHS Hardiness Rating H5
Conservation status Least concern (LC)
An evergreen shrub usually not more than 10 ft high in the wild; bark peeling; young shoots glabrous. Leaves oval, 3 to 51⁄2 in. long, 11⁄4 to 21⁄2 in. wide; abruptly tapering at the apex, tapering, rounded, or slightly heart-shaped at the base, glabrous above, densely covered beneath with a red-brown felt; stalk 1⁄2 to 1 in. long, often reddish. Flowers rosy purple of numerous shades, or almost white, 2 in. across, produced during April in rather loose clusters about 4 in. wide. Calyx downy, small and scarcely lobed. Corolla broadly bell-shaped, with five notched lobes, the upper ones dark purple-spotted. Stamens ten, glabrous or sometimes downy towards the base; flower-stalk about 1 in. long. Bot. Mag., t. 3759. (s. Campanulatum)
Native of the Himalaya from Kashmir to some way east of Bhutan, from 10,000 to 14,000 ft. According to Loudon, Loddiges’ nursery received seeds from Wallich in 1825, but there may have been earlier introductions to private gardens. In 1844 it was referred to as ‘one of the best hardy evergreens we have’ (Gard. Chron. (1844), p. 379). It is very variable in the colour of the flowers, which are sometimes quite pale, sometimes of a bright bluish purple, sometimes lilac or even white; in the amount of felt at the back of the leaf; and in the colour of the leaf-scales that accompany the young bursting shoots, which are sometimes rich crimson, sometimes green. At its best it is a beautiful rhododendron, though not held in much regard at the present time. In Scotland it has attained a remarkable size, e.g., 30 ft in height and 41⁄2 ft in girth at breast height at Benmore, Argyll (R.C.Y.B. 1964, p. 13; op. cit., 1968, fig. 17).
subsp. aeruginosum (Hook.f.) Chamberlain R. campanulatum var. aeruginosum (Hook.f.) Cowan and Davidian; R. aeruginosum Hook.f. – This has a more easterly distribution than the typical subspecies, but there is some overlap (Rev. 2. p. 373).
cv. ‘Graham Thomas’. – A seedling of great promise, raised at the Knap Hill Nursery, Surrey, with good foliage and lavender blue flowers. Registered 1985 and propagated.
Flowers large, of a beautiful shade of blue-mauve. Raised at the Knap Hill Nursery. Award of Merit when shown from Exbury, May 5, 1925.Two other forms that have received the same award are: ‘Roland Cooper’ and ‘Waxen Bell’, both exhibited by the Royal Botanic Garden, Edinburgh (see R.C.Y.B. 1965, p. 166, and op. cit., 1966, p. 163).
R. campanulatum var. wallichii (Hook. f.) Hook. f
R. aeruginosum Hook.f.
Dwarf shrub, 0.5–2.5m; flowers pale mauve to plum purple; leaves 7–9.5cm long, with a bluish metallic bloom when young.
Distribution Sikkim, Bhutan, ?E Nepal.
Awards AM 1925 (L. de Rothschild, Exbury) to a clone ‘Knaphill’; flowers a fine lavender blue. AM 1964 (Royal Botanic Garden, Edinburgh) to a clone ‘Roland Cooper’; flowers white, shaded mauve. AM 1965 (Royal Botanic Garden, Edinburgh) to a clone ‘Waxen Bell’; flowers purple, with darker spots. AGM 1993, to a clone ‘Knaphill’
Taxonomic note (R. aeruginosum Hook.f.)
Plants from Bhutan, with deep plum purple flowers and a very thick leaf indumentum, which are very slow-growing in cultivation, are perfectly distinct from subsp. campanulatum. However, plants from E Nepal, known only to me from photographs, apparently have much paler flowers and are intermediate in stature. R. campanulatum is close to R. wallichii but can be distinguished by the more dense and paler leaf indumentum.
Shrub or small tree, to 4.5m; flowers white to pale mauve; leaves 9.5-14cm long without a metallic bloom when young.
Distribution N India (Kashmir to Sikkim), Nepal, Bhutan.
Plants from NW India, typified by the clone ‘Roland Cooper’, differ from those from E Nepal, Sikkim and Bhutan in having relatively large leaves.
R. aeruginosum Hook. f