Rhododendron danbaense L. C. Hu

Without seeing the type specimen of Rhododendron danbaense, it cannot be confirmed if the leaf indumentum is truly unistrate, and it is therefore uncertain how this species relates to R. nigroglandulosum and to R. bureavioides (with a very poorly developed, white lower layer of indumentum). Rhododendron bureavioides should probably be recognized as a distinct species (see under R. bureavii above). Its type has large calyx lobes 6–8 mm, a character that will technically distinguish it from both R. danbaense and R. nigroglandulosum. All three species are distributed in the same region, close to and N of Kangding in W Sichuan.

Shrubs, 3–4 m tall; branchlets subterete, 8–10 mm in diam., densely fawn to grayish branched-pubescent when young. Petiole stout, 10–20 mm, densely gray branched-villous; leaf blade thickly leathery, oblong-elliptic to elliptic, 9–12.5 × 3.5–4.5 cm; base cordate to rounded; margin slightly revolute; apex acuminate; abaxial surface brown to yellowish brown, indumentum thick, 1-layered, densely villous, hairs multi-branched; adaxial surface with grooved midrib tomentose, otherwise glabrous. Inflorescence umbellate, 6–8-flowered; rachis ca. 3 mm; perulae deciduous. Pedicel 1–2 cm, densely branched-villous and with long-stalked glands; calyx yellow-green, lobes 5, 2.5–3 mm, broadly triangular, sparsely villous, margin ciliate with long-glandular hairs; corolla funnelform-campanulate, white, with copious carmine spots, 4–4.5 × ca. 4.5 cm; lobes 5, ca. 1.5 × 2.3 cm, emarginate; stamens 10, unequal; filaments glabrous or puberulent at base; ovary 5–6 mm, densely long-glandular-hairy, villous towards apex; style ca. 2.8 cm, shorter than corolla and longer than stamens, densely villous and long-glandular-hairy below middle; stigma discoid. Fl. May.

W Sichuan (Danba).

Forests; ca. 3400 m.