Description from Flora of China
Shrubs or small trees, 3–5 m tall; young shoots densely rufous- to white-tomentose, later glabrescent. Petiole cylindric, 10–15 mm, stellate-tomentose, glabrous when mature; leaf blade leathery, oblong-elliptic or elliptic-lanceolate, 7–12 × 2.5–5.5 cm; base broadly cuneate to rounded or truncate to slightly cordate; apex acute, apiculate; abaxial surface pale green, glabrous except for midrib rufous stellate-tomentose or floccose near base; adaxial surface green, papillose, glabrous; midrib conspicuously prominent abaxially; lateral veins 12–15-paired, obscure. Inflorescence 8–12-flowered; rachis 10–20 mm, white-tomentose. Pedicel 1–2 cm, with same hairs; calyx lobes 5, ca. 2 mm, triangular, apex acute, pubescent outside; corolla campanulate, white, or purple to pink, with deep purple flecks, 3–3.5 cm, nectar pouches lacking, lobes 5, suborbicular, ca. 1.5 × 2 cm, emarginate; stamens 10, unequal, 1.5–3 cm, filaments pubescent at base; ovary oblong-ovate, ca. 5 mm, brown stellate-tomentose; style stout, glabrous, stigma slightly swollen, small. Capsule cylindric, 15–20 × 4–5 mm, clad with dense hairs. Fl. May–Jul, fr. Sep–Nov.
This species is distinctive within Rhododendron subsect. Irrorata on account of the stellate hairs at the base of the leaf blade abaxially and on the pedicels and ovary. The stellate indumentum on the petioles suggests that R. sikangense belongs to R. subsect. Maculifera.
Mixed forests, thickets, alpine slopes; 2800–4500 m. W Sichuan, NE Yunnan.