Description from Flora of China
Azalea oldhamii (Maximowicz) Masters; Rhododendron oldhamii var. glandulosum Hayata; R. ovatosepalum Yamamoto.
Shrubs, semievergreen, to 3 m tall; young shoots with spreading red-brown flat glandular hairs, also pubescent. Summer and winter leaves different. Petiole 4–6 mm, with dense short brown glandular setae and flat hairs; leaf blade thinly leathery, elliptic or elliptic-lanceolate, 2–7.8 × 1.5–5 cm; base broadly cuneate; margin slightly revolute, ciliate; apex obtuse and mucronate; adaxial surface densely shortly setose, later subglabrous. Inflorescence 2–4-flowered. Pedicel 0.6–1 cm, shortly glandular setose; calyx lobes unequal, triangular-ovate or ovate-lanceolate, 3–8 mm, outer surface with long red-brown glandular hairs on margin; corolla broadly funnelform, brick-red, lacking flecks, 4–4.8 × 3–5 cm; tube tapering toward the base, 1.8–2.4 cm, glabrous; lobes ovate or elliptic-ovate; stamens 10, unequal, shorter than the corolla, filaments puberulent in the lower half; ovary ovoid, densely yellow-brown glandular-setose; style longer than stamens, exserted, glabrous. Capsules broadly ovoid, 9–15 mm, glandular-setose, calyx persistent. Fl. May–Jul(–Oct).
Mountain thickets; ca. 2800 m. Taiwan.