Description from Flora of China
Rhododendron campanulatum D. Don var. wallichii (J. D. Hooker) Hooker; R. heftii Davidian.
Shrubs 2–4 m tall; young shoots ca. 5 mm in diam., glabrous or floccose. Petiole often reddish, 10–15 mm, glabrous or sometimes tomentose; leaf blade leathery, elliptic to oblong-
obovate, 7–12 × 2.5–5 cm; base rounded or cordate; margin slightly revolute; apex obtuse or rounded, mucronate; abaxial surface glabrous or brown to ferruginous, indumentum granular, discontinuous, ± detersile, hairs fasciculate. Inflorescence racemose-umbellate, 5–8-flowered; rachis ca. 20 mm, hairy or glabrous. Pedicel 0.1–0.25 cm, glabrous or floccose; calyx lobes 0.5–2 mm, rounded or triangular, glabrous or floccose; corolla broadly campanulate, lilac-purple, purplish red or whitish, ± deeply rose-spotted, 3.5–5 cm, lobes 5; stamens 10, unequal; filaments pubescent at base; ovary 5–7 mm, 5–6-locular, glabrous, rarely with a few pubescent hairs; style glabrous; stigma lobed. Capsule slightly curved, 15–30 × 5–7 mm, glabrous. Fl. May–Jun, fr. Jul–Sep.
Mixed forests, mountain slopes; 3000–4300 m. S Xizang [Bhutan, NE India (Darjiling), E Nepal, Sikkim].