Description from Flora of China
Rhododendron argenteum J. D. Hooker; R. longifolium Nuttall; Waldemaria argentea (J. D. Hooker) Klotzsch.
Large trees, 8–10 m tall; branchlets stout, ca. 8 mm in diam. Petiole 35–50 mm, sparsely whitish hairy; leaf blade leathery, oblong-lanceolate to oblanceolate, 14–30 × 8–13 cm; base cuneate to broadly cuneate; apex obtuse or acuminate, cuspidate; abaxial surface silvery-white, indumentum thin, agglutinated; adaxial surface shiny, glabrous, midrib and lateral veins strongly prominent abaxially. Inflorescence a large globose corymb, 20–25-flowered; rachis 40–50 mm. Pedicel 2–3 cm, glandular, sometimes also tomentose; calyx teeth 8, 1–2 mm, undulate, glandular; corolla ventricose-campanulate, pale rose in bud, later white or creamy-white, with purple nectar pouches, 5–7 cm, lobes 8; stamens 16, 3.5–5 cm, filaments pubescent at base or glabrescent; ovary ca. 9 mm, 16-locular, densely glandular-hairy and tomentose; style stout, ca. 3.8 cm, glabrous or with a few glands at base, stigma large, discoid. Capsule oblong-cylindric, ca. 45 × 14 mm. Fl. May, fr. Aug–Sep.
Mixed mountain forests; 1600–2900 m. S Xizang [Bhutan, N India, Nepal, Sikkim].