An evergreen shrub 6 to 10 ft high with glabrous, red, peeling bark; young shoots slender, glaucous, scaly. Leaves ovate-lanceolate, rounded at the base, sharply pointed, 2 to 3 in. long, 1 to 11⁄4 in. broad, bright green and glabrous above, glaucous and thickly furnished with scales beneath; stalk 1⁄4 to 1⁄3 in. long. Flowers fragrant, opening in May and June, usually in threes, at the end of the shoot when young growths are pushing. Calyx small, shallowly undulated; flower-stalks 1⁄2 to 7⁄8 in. long. Corolla pale yellow spotted with green, with a short funnel-shaped tube and five spreading oblong lobes giving the flower a diameter of 11⁄2 to 2 in., scaly outside. Stamens ten, 1⁄2 to 1 in. long, downy towards the base; ovary scaly; style longer than stamens, glabrous. (s. and ss. Triflorum)
Native of the eastern Himalaya; discovered by J. D. Hooker in the Sikkim Himalaya in 1849 and introduced by him. It is not a showy plant, although the flowers are interesting in their unusual colour. The red, semi-transparent, loose bark is also attractive with sunlight behind it. It is hardy.
var. mahogani Hutch. – This was found by Kingdon Ward in the Tibetan province of Kongbo, near Tsela Dzong on the Tsangpo, growing with the typical state. 'Another rhododendron which grew here to perfection was R. triflorum and its dark variety, which I called the "Mahogany Triflorum" (K.W. 5687). In the valley it is a small compact scrubby plant with lemon-yellow flowers; but on these sheltered tree-clad slopes it formed a large bush 12 or 15 ft high with reddened flowers which were especially beautiful when the light shone through them. . . . The flowers vary from pale yellow – the typical R. triflorum colour – to salmon pink, mahogany, burnt sienna, and other tones. Moreover, the bushes were smothered in bloom and are as hardy as anything' (Kingdon Ward, The Riddle of the Tsangpo Gorges, p. 44). This variety sounded promising, but proved a sad disappointment when it first flowered in gardens. 'Was the dingy horror under the number KW 5687 shown in the Triflorum Class, was this the Mahogany Triflorum we have so anxiously awaited ?'(G. H. Johnstone in his Report on the Rhododendron Show for 1931).
R. bauhiniiflorum Watt ex Hutch. – Very closely allied to R. triflorum but with more widely expanded flowers. Native of Assam in the Naga Hills and Manipur; discovered by Sir George Watt in 1881-2 but probably not introduced until Kingdon Ward sent seeds from Mt Japvo in 1928. It is a finer species than R. triflorum and almost as good as R. lutescens, besides being very much later-flowering. There is a fine clump in the Savill Garden, Windsor Great Park, which is about 10 ft high and was in flower in the fourth week of May in 1973.
From the Supplement (Vol. V)
The var. mahogani is not recognised in the Edinburgh revision, understandably so, as it is only a minor colour-form linked to the typical state by intermediates.
var. bauhiniiflorum (Hutch.) Cullen R. bauhiniiflorum Hutch. – The only distinguishing character of this variety is the widely expanded flower.