Description from Flora of China
Azalea mollis Blume, Catalogus, 44. 1823; A. sinensis Loddiges; Rhododendron sinense (Loddiges) Sweet.
Shrubs, 0.5–2 m tall; branches densely gray-white-pubescent, also sparsely setose when young. Petiole 2–6 mm, puberulent and ± setose; leaf blade papery, oblong to oblong-lanceolate, 5–11 × 1.5–3.5 cm; base cuneate; margin ciliate; apex obtuse and mucronate; abaxial surface densely gray-white-pubescent, yellow-brown setose along midrib; adaxial surface sparsely to densely puberulent when young. Inflorescence terminal, racemose-umbellate: flowers opening before or with the leaves; many-flowered. Pedicel 1–2.5 cm, pubescent and sparsely setose; calyx lobes small, rounded, pubescent and setose-ciliate; corolla broadly funnelform, yellow or golden yellow, with dark red flecks on lobes, ca. 4.5 × 5–6 cm; tube cylindric, tapering towards base, ca. 26 mm wide, outer surface puberulent; lobes 5, elliptic or ovate-oblong, ca. 2.8 cm, puberulent on outer surface; stamens 5, unequal; filaments flat, puberulent below; ovary conical, ca. 4 mm, densely gray-white-pubescent, also sparsely setose; style to 6 cm, glabrous. Capsule conical-cylindric, 5-ribbed, 25–35 mm, puberulent and sparsely setose. Fl. Mar–May, fr. Jul–Aug.
Kron (Edinburgh J. Bot. 50: 279. 1993) treated Rhododendron japonicum A. Gray as R. molle subsp. japonicum (A. Gray) Kron. This taxon differs from subsp. molle in its more densely hairy fruit and yellow to orange-red flowers. It is restricted to Japan.
Pinus forests, thickets on mountain slopes, exposed grassy hillsides, ridges; near sea level to 2500 m. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Sichuan, Yunnan, Zhejiang.