紫玉盘杜鹃 zi yu pan du juan

Rhododendron dendritrichum I. B. Balfour & Forrest; R. monbeigii Rehder & E. H. Wilson; R. niphargum I. B. Balfour & Kingdon Ward; R. uvariifolium var. griseum Cowan.

Shrubs or trees, 2–10 m tall; young shoots whitish or gray-tomentose. Petiole 10–20 mm, gray-tomentose; leaf blade leathery, oblanceolate to oblong-oblanceolate or obovate, 11–24 × 3.5–6.5 cm; base cuneate, sometimes obtuse; apex obtuse or acute, mucronate; abaxial surface gray-white to gray-brown, smooth, indumentum dense, continuous, hairs dendroid-branched. Inflorescence racemose-umbellate, 8–18-flowered; rachis ca. 10 mm. Pedicel 1.5–2.5 cm, sparsely floccose or almost glabrous; calyx lobes 5, 0.5–1 mm; corolla campanulate, white to pink or rose, with crimson basal blotch and purple spots on upper lobes, 3–3.5 cm, lobes 5; stamens 10, unequal, filaments pubescent at base; ovary glabrous; style pistil slightly shorter than or nearly equaling corolla, glabrous; stigma capitate. Capsule elongated, strongly curved, 3.5–5 × 3–4 mm, glabrous. Fl. Apr–Jun, fr. Aug–Oct.

Coniferous forests, Rhododendron thickets, mountain slopes; 2100–4000 m. SW Sichuan, SE Xizang, NW Yunnan.

Perhaps var. griseum should be maintained, but at subspecific rank on account of the different leaf indumentum and the more westerly distribution than typical Rhododendron uvariifolium.