312. Rhododendron dimitrum I. B. Balfour & Forrest, Notes Roy. Bot. Gard. Edinburgh. 11: 50. 1919.
苍山杜鹃 cang shan du juan
Shrubs, 2–4 m tall; branches stout; young shoots glabrescent. Petiole cylindric, ca. 10 mm, glabrescent; leaf blade leathery, oblong-elliptic to lanceolate, 4–7 × 1.5–2.5 cm; base cuneate or obtuse, narrowly decurrent; margin revolute; apex cuspidate; both surfaces glabrous; abaxial surface glaucescent; adaxial surface green; midrib prominent abaxially, lateral veins 15–17-paired, obscure. Inflorescence racemose-umbellate, 10–12-flowered; rachis 7–10 mm, pubescent. Pedicel 0.5–1 cm, densely dendroid-pubescent, eglandular; calyx pink, cupular; lobes 5, 3–5(–10) mm, oblique, oblong, triangular or ovate, fringed at margin; corolla tubular-campanulate, fleshy, deep rose, with crimson flecks, 3–4 cm, with 5 deep purple nectar pouches, outer surface glabrous, lobes 5, rounded emarginate; stamens 10, unequal, 1–2 cm, filaments pubescent at base; ovary cylindric-conoid, ca. 5 mm, densely tomentose; style 1.5–2 cm, lower 1/2 tomentose, stigma small. Capsule not known. Fl. Apr–May.
Mixed forests, open thickets; 3000–3300 m. W Yunnan.
This species is distinctive within Rhododendron subsect. Irrorata on account of the large calyx and the densely tomentose ovary and proximal half of the style. It may have originated as a hybrid between R. irroratum and R. neriiflorum.