337. Rhododendron niveum J. D. Hooker, J. Hort. Soc. London. 7: 78. 1852.
西藏毛脉杜鹃 xi zang mao mai du juan
Shrubs or trees, 2–6 m tall; bark cinereous; older branches brownish, glabrescent; branches ca. 6 mm in diam. below inflorescence; young shoots grayish green, densely tomentose. Petiole 13–15 mm; leaf blade leathery, oblanceolate to elliptic, 8.5–11 × 3.6–4.6 cm; base tapering or rounded; margin revolute; apex obtuse or rounded, apiculate; abaxial surface with 1-layered indumentum densely compacted, fawn, glabrescent, hairs dendroid; adaxial surface of unfolding leaves scattered white floccose, at maturity glabrous except for traces of tomentum chiefly in groove of midrib; midrib prominent abaxially, grooved adaxially; lateral veins 11–16 on each side. Inflorescence spherical, dense, 15–20-flowered, rachis ca. 20 mm, fulvous tomentose. Pedicel ca. 1 cm, densely white- to rufous-tomentose; calyx teeth minute, 1–2 mm, tomentose; corolla tubular-campanulate, deep magenta to deep lilac, 3–3.5 cm, with 5 deep purple basal nectar pouches; stamens 10, unequal, 1.8–2.8 cm, filaments glabrous; ovary cylindric or oblong, ca. 6 mm, densely whitish to tawny-tomentose; style glabrous, stigma capitate, small. Capsule shortly cylindric, blunt, 15–18 mm, blackish, roughened with vestiges of tomentum. Fl. Apr–May, fr. Aug–Sep.
Mixed forests, rocky valleys; 2600–3500 m. S Xizang [Bhutan, NE India, Sikkim].