Description from Flora of China
Rhododendron daiyuenshanicum P. C. Tam, nom. illeg. superfl.; R. daiyunicum P. C. Tam; R. farrerae Sweet var. mediocre Diels; R. gnaphalocarpum Hayata; R. shojoense Hayata; R. umbelliferum H. Léveillé.
Shrubs, deciduous, 1–3 m tall; branches verticillate, softly yellowish-brown hairy, glabrescent. Petiole 5–7 mm, glabrescent; leaf blade papery to almost leathery, elliptic, ovate-lanceolate or triangular-ovate, 4–7.5 × 2–4 cm; base obtuse or subrounded; margin slightly revolute; apex acute and mucronate; both surfaces yellowish brown-villous, glabrescent, rarely abaxial surface thinly persistently floccose. Inflorescence usually 2-flowered: flowers appearing before the leaves. Pedicel 0.7–1 cm, densely softly yellow-brown hairy; calyx shallowly lobed, densely softly yellow-brown hairy; corolla funnelform, purplish red, with purple-red flecks on upper lobes, 3–3.5 cm; tube ca. 4 mm in diam.; lobes deeply divided, oblong, both surfaces glabrous; apex obtuse and rounded; stamens 8–10, unequal, shorter than, or as long as the corolla, filaments flat, glabrous; ovary ovoid, densely yellow-brown villous; style longer than stamens, glabrous. Capsule ellipsoid-ovoid, 6–9(–18) mm, densely shiny-brown-villous. Fl. Apr–May, fr. Jun–Nov.
Rhododendron daiyunicum is probably a distinct species. The name R. daiyuenshanicum was published a year later based on the same type.
Specimens collected in Hubei by Henry were referred by Diels (Bot. Jahrb. Syst. 29: 513. 1900) to Rhododendron farrerae var. weyrichii (Maximowicz) Diels. This species (R. weyrichii Maximowicz) is exclusively Japanese. The Chinese specimens cited by Diels were mentioned in the protologue of R. mariesii, and one is probably the type of the latter name.
Open forests, submontane regions; 600–1500 m. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Henan, Hebei, Hubei, Hunan, Jiangsu, Jiangxi, Shanxi, Sichuan, Taiwan, Zhejiang.