Rhododendron stewartianum Diels


R. aiolosalpinx Balf. f. & Farrer; R. nipholobum Balf. f. & Farrer

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An evergreen shrub up to 10 ft high, young shoots glabrous. Leaves obovate to oval, 2 to 412 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 14 in. long. Flowers in trusses of three to seven, opening in February, March, or April. Corolla tubular-campanulate, 134 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.

R. eclecteum Balf. f. & Forr. – Allied to R. stewartianum, but with the leaves always glabrous beneath except for the sometimes hairy midrib. Also, in its typical state, it is very easily distinguished by its almost sessile, obovate leaves, slightly cordate at the base; in the original description their shape was likened to that of a Jargonelle pear. It appears to be a native mainly of the region from the Mekong-Salween divide around Ka-kar-po westward to upper Burma but has also been collected in S.W. Szechwan. The variation in colour is as remarkable as it is in R. stewartianum. Perhaps the finest, and certainly the most distinct, are those with pure white flowers, with blackberry-coloured nectar-pouches and anthers. Such is Kingdon Ward's 6869, from the Seinghku valley, north-west upper Burma. His 6900, from the same area, has flowers of a deep glowing pink. Unfortunately it is just as early-flowering as R. stewartianum.

var. bellatulum Tagg – Leaves with distinct petiole, more or less oblong, rounded or obtuse at the base.

var. brachyandrum (Balf. f. & Forr.) Tagg R. brachyandrum Balf. f. & Forr. – Flowers deep rose or crimson.

From the Supplement (Vol. V)

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).



Other species in the genus