438. Rhododendron chamaethomsonii (Tagg) Cowan & Davidian, Rhododendron Year Book. 6: 70. 1951.
云雾杜鹃 yun wu du juan
Upright shrubs, 0.15–0.9 m tall, bark falling off in flakes; shoots 2.5–3 mm in diam. below inflorescence; young shoots glandular-hairy or tomentose; bud scales usually deciduous. Petiole 7–16 mm, glandular; leaf blade leathery, obovate or oblong-obovate, 2.5–6.5(–9) × 1.1–3.5(–4) cm; base obtuse, decurrent; margin revolute; apex rounded, apiculate; abaxial surface pale green, puberulent and glandular towards the base, or glabrous; adaxial surface green, glabrous; midrib grooved adaxially; lateral veins 8–10-paired, impressed adaxially. Inflorescence umbellate, 1–4-flowered. Pedicel 0.8–1.3(–1.6) cm, glandular; calyx 1–4 mm; corolla tubular-campanulate whitish to pale pink to deep crimson, 2.6–2.8(–4.8) cm, pubescent at base outside; lobes 5, unequal, 1.5–3.4 cm, emarginate; ovary conoid, 5–6 mm, hairy, with or without glandular hairs; style glabrous. Capsule cylindric, 15–23 mm, with vestiges of glands; calyx persistent. Fl. Jun.
Rhododendron thickets, alpine thickets, stony slopes, damp rocky alpine slopes; 3300–4500 m. SE Xizang, NW Yunnan.
At least some forms of this entity may be hybrids of Rhododendron forrestii. One of us (Chamberlain) has seen one such hybrid between the latter species and R. stewartianum in the field above Gongshan in NW Yunnan. This plant was a good fit with R. chamaethomsonii.