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 stewartianum' from the website Trees and Shrubs Online (treesandshrubsonline.
Shrub, 0.5–2.5 m; bark smooth or rough, peeling on smaller branches; young shoots often glandular. Leaves 4–12 × 2–6.5 cm, obovate to elliptic, base rounded, upper surface glabrous, lower surface with a mammillate epidermis and a thin more or less persistent to evanescent indumentum interspersed with sessile glands; petioles usually glabrous occasionally with a few glands. Flowers 3–7, in lax truss; calyx (2–)5–15 mm, cupular; corolla white or cream to pale (rarely deep) rose, with or without purple flecks, campanulate to tubular-campanulate, with nectar pouches, 35–55 mm; ovary usually densely glandular, style glabrous. Flowering February-April. Royal Horticultural Society (1997).
Distribution Myanmar NE China SE Tibet, NW Yunnan
Habitat 3,000–4,250 m
RHS Hardiness Rating H4
Awards AM 1934 (L. de Rothschild, Exbury).
Conservation status Least concern (LC)
Taxonomic note This is a variable species, especially with respect to the flower colour. It is allied to R. eurysiphon and perhaps also R.eclecteum, though the presence of a more or less persistent leaf indumentum will distinguish it from these two species. Royal Horticultural Society (1997).
An evergreen shrub up to 10 ft high, young shoots glabrous. Leaves obovate to oval, 2 to 41⁄2 in. long, more or less rounded at both ends, grey-green above, undersurface covered with a powdery indumentum or with a thin veil of hairs; stalk about 1⁄4 in. long. Flowers in trusses of three to seven, opening in February, March, or April. Corolla tubular-campanulate, 13⁄4 in. long and wide, with five rounded, notched lobes; the colour, according to Farrer, ranging from ‘cream and pure white through all flushes and shades of pink to rich deep rose’; another collector found plants with ‘scarlet red’ flowers, and others are described as ‘deep crimson’. Stamens ten, downy at the base. Ovary glandular; style glabrous. (s. and ss. Thomsonii)
Native of N.E. Burma and of bordering parts of S.E. Tibet and N.W. Yunnan, with its greatest concentration in the mountains between the Salween and the upper eastern Irrawaddy, from 26° 20′ N. to about 28° 50′ N.; discovered by Forrest in 1904; introduced by Farrer and Cox in 1919 from the Chimi-li and simultaneously by Kingdon Ward from Imaw Bum, a few miles farther west. Forrest sent numerous batches of seed during the 1920s, some from the Chimi-li but mostly from farther north. Kingdon Ward’s 8294 from the Mishmi Hills, Assam, is near to R. stewartianum.
R. stewartianum first flowered in the spring of 1930 at Exbury, Logan, and Bodnant, and received an Award of Merit when shown from the first-named garden on March 20, 1934. It is remarkably variable in the colour of its flowers and Farrer found, in one area, plants growing together bearing flowers of nearly all the shades mentioned above. In some plants the colour is deepest near the margin of the corolla, paling downwards. Although quite hardy, R. stewartianum flowers too early to be of value for most gardens – in some years it is in full bloom in February.
Some field-specimens placed under R. stewartianum are natural hybrids (Rev. 2, p. 426).
R. eclecteum – The var. bellatulum is not recognised in the Edinburgh revision.
As mentioned under R. chaetomallum in this supplement, hybrids occur in the wild between that species and R. eclecteum (R. × hemigymnum).
R. eurysiphon Tagg & Forr. – This species was formerly grouped with R. martinianum in s. Thomsonii ss. Selense, but Dr Cullen points out that the corollas have nectaries, a character that excludes it from subsect Selensia. Its proper place is in subsect. Thomsonia, near to R. eclecteum, of which it may be a natural hybrid (Rev. 2, pp. 426–8).
R. brachyandrum Balf. f. & Forr