Description from Flora of China
Rhododendron bicorniculatum P. C. Tam; R. gratiosum P. C. Tam; R. papyrociliare P. C. Tam.
Shrubs, deciduous, 1–3(–7.5) m tall; old branches with hair remains; young shoots coarsely red-brown strigose. Summer and winter leaves different. Petiole 4–10 mm, densely red-coarse brown strigose; leaf blade leathery, elliptic-lanceolate to elliptic-obovate, 3–7.8(–11) × 1.3–4 cm; base cuneate; margin slightly revolute, coarsely strigose; apex acuminate and mucronate; abaxial surface sparsely rufous-strigose; adaxial surface ± glabrescent; lateral veins not reaching the margin. Inflorescence 7–16-flowered. Pedicel 0.5–1.2 cm, densely softly brown-hairy; calyx very small, softly yellowish-brown-hairy; corolla narrowly funnelform, lilac, 1.5–2.2 cm; tube cylindric, ca. 13 mm, glabrous; lobes spreading, oblong-lanceolate, apex obtusely pointed; stamens 5, unequal, 1.7–2.5 cm, exserted, filaments broader and glabrous at base; ovary ovoid, ca. 2 mm, densely long silky red-brown-strigose; style longer than stamens, glabrous. Capsules long-ovoid, 9–14 × ca. 3 mm, densely coarsely red-brown-strigose. Fl. Mar–Jun, fr. Jul–Nov.
Rhododendron bicorniculatum and R. gratiosum may in fact be distinct species.
See also: JIN Xiaofeng et al. 2009. Taxonomic revision of Rhododendron mariae (Ericaceae). Nordic J. Bot. 27: 186-202.
Mountain thickets; 500–1300 m. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hunan, Jiangxi.