Rhododendron diphrocalyx Balf. f.

Synonyms: R. burriflorum Balf. f. & Forr.

An evergreen shrub 5 to 15 ft high; young shoots and leaf-stalks clothed with a mixture of glandular bristles and short down. Leaves 21⁄2 to 6 in. long, 1 to 21⁄4 in. wide, elliptical to oblong, bright green above, pale and rather glaucous beneath, nearly or quite glabrous at maturity except on the midrib; stalk 1⁄2 to 3⁄4 in. long. Flowers opening in April and said to have as many as twenty flowers in a truss. Calyx very large, 1⁄2 to 3⁄4 in. long, unequally five-lobed, rather bell-shaped, bright red, but conspicuously spotted on one side. Corolla bell-shaped, 11⁄4 in. long, bright red to light rosy crimson with a crimson blotch at the base and crimson spots. Stamens ten, slightly downy at the base; ovary covered with tawny down as is also the base of the style. (s. Barbatum ss. Glischrum)

Native of W. Yunnan, China. It first appeared as a ‘rogue’ amongst R. habrotrichum in E. J. P. Magor’s garden at Lamellen in Cornwall, where it flowered in 1918. Sir Isaac Balfour appears first to have regarded it as a hybrid. Tagg, however, united with it the R. burriflorum described as a species by Balfour from a specimen collected by Forrest in W. Yunnan in 1918. It is remarkable for the size and colouring of its corolla-like calyx. A handsome rhododendron scarcely hardy enough to succeed at Kew.

From the Supplement (Vol. V)

Probably a natural hybrid of R. habrotrichum, with a member of subsect. Neriiflora as the other parent (Rev. 2, pp. 287-8).