Description from Flora of China
Rhododendron chengshienianum W. P. Fang.
Shrubs, 1–3 m tall; young shoots thin, densely glandular-scaly. Petiole 6–10 mm, densely glandular-scaly; leaf blade leathery, elliptic, ovate-lanceolate or oblong, 4–8 × 1.8–3 cm; base broadly cuneate to obtuse; apex acuminate, acute or obtuse, apiculate; abaxial surface gray-green, scales to 1 × their own diameter apart, unequal, yellowish brown or brown; adaxial surface scaly, young leaves with midrib hairy or not. Inflorescence terminal, rarely subterminal, umbellate or shortly racemose, 3–4(–7)-flowered; rachis 2–4 mm. Pedicel 0.5–1 cm, scaly; calyx rimlike or undulate, 0.5–1 mm, scaly; corolla broadly funnelform-campanulate, yellow or pale yellow, or pale greenish yellow, inside with yellowish green markings and pubescent, 3–3.5 cm, outer surface scaly; stamens unequal, 1.8–4.5 cm; filaments densely pubescent below; ovary 5-locular, densely scaly; style longer than corolla, glabrous. Capsule cylindric, 6–15 mm. Fl. May–Jun, fr. Sep–Oct.
Geng et al. (in Acta Phytotax. Sin. 41: 493. 2003) proposed that Rhododendron ambiguum should be treated as a synonym of R. wongii. The holotype specimen of R. wongii is reputed to be very poor and may be depauperate. There is evidently little to separate these two species.
Forests, thickets; 2300–3300(–4500) m. C and W Sichuan.