52. Rhododendron ambiguum Hemsley, Bot. Mag. 137: t. 400. 1911.
问客杜鹃 wen ke du juan
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.
Forests, thickets; 2300–3300(–4500) m. C and W Sichuan.
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.