Description from Flora of China
Rhododendron thomsonii J. D. Hooker var. cyanocarpum Franchet, J. Bot. (Morot) 9: 389. 1895; R. cyanocarpum var. eriphyllum (I. B. Balfour & W. W. Smith) Tagg; R. hedythamnum I. B. Balfour & Forrest var. eglandulosum Handel-Mazzetti.
Shrubs or small trees 2–4 m tall; older branches grayish, bark falling off in flakes; branchlets 4–5 mm in diam. below inflorescence; young shoots greenish, glabrous. Petiole often slightly winged, 20–30 × 3–4 mm; leaf blade leathery, broadly elliptic to suborbicular, 8–13 × 5–9 cm; base rounded; margin reflexed; apex apiculate; abaxial surface glaucous, glabrous or with a few scattered hairs; adaxial surface deep green, glabrous; midrib flat adaxially; lateral veins 11–14-paired, slightly impressed on both surfaces. Inflorescence 5–9-flowered; rachis 8–15 mm, pubescent or glabrous. Pedicel 1–2 cm, glabrous; calyx pale pink, cupular, fleshy; lobes 5, 7–12 mm, glabrous; corolla campanulate or funnel-campanulate, fleshy, creamy-white to clear pink, flecks lacking, 5–6 cm, base with dark nectar pouches; lobes 5, rounded, ca. 1.5 × 2.3 cm, emarginate; stamens 10, unequal, 2–4 cm, filaments glabrous; ovary conical 6–7 mm, glabrous or with a few glands; style 2.5–3 cm, glabrous. Capsule oblong, blunt, 12–20 × 7–10 mm, glaucous, base usually enclosed by persistent calyx. Fl. Apr–May, fr. Aug–Oct.
Pinus forest margins, Rhododendron thickets; 3000–4000 m. W Yunnan.