142. Rhododendron sulfureum Franchet, Bull. Soc. Bot. France. 34: 283. 1887.
硫磺杜鹃 liu huang du juan
Rhododendron cerinum I. B. Balfour & Forrest; R. commodum I. B. Balfour & Forrest; R. theiochroum I. B. Balfour & W. W. Smith.
Shrubs, evergreen, usually epiphytic, 0.3–1.6 m tall;
branchlets scaly, usually setose. Petiole 4–12 mm, densely scaly, often setose; leaf blade leathery, obovate, ovate, oblong-obovate, or elliptic to oblanceolate, 2.6–8.6 × 1.5–4.5 cm; base obtuse or tapering; margin often ciliate when young; apex rounded or subacute, mucronate; abaxial surface glaucous green, scales ca. 0.5 × their own diameter apart, unequal, dark brown or brown, sunk in pits, with crenulate edges, rims upturned; adaxial surface green, somewhat shiny, scaly or glabrous. Inflorescence 4–8-flowered. Pedicel 0.8–2 cm, scaly, sometimes setose; calyx lobes 3–6 mm, ovate to oblong, persisting to enclose mature capsule, scaly, margin usually cilite; corolla broadly campanulate, bright yellow, rarely greenish, not spotted, 1.3–2 cm, tube 8–11 mm, outer surface scaly, sometimes sparsely pubescent, inner surface pilose, lobes rounded; stamens 10, filaments pubescent towards base or in lower 1/2; ovary densely scaly; style stout, sharply bent, short, scaly at base. Capsule cylindric-ovoid, 8–11 mm, densely scaly. Fl. Apr–Jun, fr. Jul–Aug.
Forests, scrub, cliffs, rocks, sometimes epiphytic; 2500–4000 m. SE Xizang, W Yunnan [NE Myanmar].