393. Rhododendron x bathyphyllum I. B. Balfour & Forrest, Notes Roy. Bot. Gard. Edinburgh. 11: 27. 1919, pro sp.
多叶杜鹃 duo ye du juan
Dwarf shrubs, 0.5–1.5 m tall; young shoots densely rust-red to gray-tomentose, later glabrescent. Petiole 5–25 mm, densely rusty red-tomentose; leaf blade thickly leathery, oblong, 4–7 × 1.5–2.5 cm; base obtuse to rounded; margin revolute; apex ± cucullate; abaxial surface with indumentum 2-layered, upper layer rust-red, thick, woolly, hairs branched, lower layer thin, appressed; adaxial surface slightly rugulose, glabrous except for tomentose groove of midrib. Inflorescence umbellate, 10–15-flowered; rachis ca. 5 mm, floccose-tomentose; perulae ± persistent during flowering period. Pedicel 1–1.5 cm, sparsely floccose-tomentose or glabrescent; calyx lobes 5, ca. 6 mm, slightly unequal, lanceolate, glabrous; corolla campanulate, white, with deep crimson spots on upper lobes and adjacent parts of tube, 3.5–3.8 cm, lobes 5, subrounded, deeply emarginate; stamens 10, 1.5–2 cm, filaments densely puberulent in lower half; ovary ca. 5 × 3 mm, densely rusty red-tomentose, eglandular; style shorter than corolla, glabrous; stigma capitate. Fl. Jul.
Forest margins, thickets, rocky mountain slopes; 3300–4300 m. SE Xizang, NW Yunnan.
Field observations in NW Yunnan indicate that this entity is a hybrid between Rhododendron aganniphum and R. proteoides.