172. Rhododendron trichostomum Franchet, J. Bot. (Morot). 9: 396. 1895.
毛嘴杜鹃 mao zui du juan
Small, intricately branched shrubs, 0.3–1(–1.5) m tall; branchlets twiggy, densely scaly, setose; bud scales deciduous, rarely persistent. Petiole 2–4 mm, scaly; leaf blade aromatic, linear, linear-lanceolate, oblong or oblanceolate, 0.8–3.2 × 0.3–0.5(–0.8) cm; base rounded to tapering; margin revolute; apex acute or obtuse, mucronate or emarginate; abaxial surface scales overlapping, pale yellowish brown to brown, arranged in 2–3 tiers, the lowermost tier golden, paler than others, rarely somewhat; adaxial surface dark green, scaly or not. Inflorescence 6–10(–20)-flowered. Pedicel (0.1–)0.2–0.5 cm, scaly; calyx lobes 0.5–2(–3) mm, oblong to ovate, persistent, scaly or not, margin usually scaly, ciliate; corolla narrowly tubular, white, pink or rose, 0.8–1.6(–2) cm, tube 4.5–8(–12) mm, outer surface densely scaly or not scaly, throat densely pilose; lobes with a few scales but no hairs; stamens 5, included in corolla tube, filaments glabrous; ovary ca. 1 mm, scaly; style turbinate, shorter than or equal to ovary. Capsule ovate to cylindric, 3–5 mm, densely scaly. Fl. May–Jul, fr. Aug–Sep.
Forests, thickets, scrub, rocky alpine meadows, open slopes, rocks; 2700–4600 m. S Qinghai, W Sichuan, SE Xizang, NW Yunnan.
Rhododendron hedyosmum I. B. Balfour (Notes Roy. Bot. Gard. Edinburgh 9: 234. 1916) was described from cultivated material derived from seed collected in Sichuan. Known only in cultivation, it is a large-flowered variant, and probably a hybrid, of R. trichostomum.