Description from Flora of China
Rhododendron sinogrande var. boreale Tagg & Forrest.
Trees, 5–12 m tall; shoots stout, 1–1.5 cm in diam., thinly silvery-gray-tomentose. Petiole stout, 30–50 mm, with silvery appressed indumentum; leaf blade thickly leathery, oblong-elliptic to oblong-oblanceolate, 20–70 × 8–30 cm; base broadly cuneate or rounded; margin slightly revolute; apex rounded or obtuse and stiffly mucronate; abaxial surface silvery-gray to buff, indumentum compacted and agglutinated; adaxial surface glabrous; midrib prominent abaxially. Inflorescence racemose-umbellate, 15–20-flowered; rachis 30–60 mm. Pedicel stout, 3–5 cm, with a dense buff tomentum; calyx oblique; lobes 8(–10), ca. 2 mm, triangular, tomentose or glabrescent; corolla ventricose-campanulate, fleshy, creamy-white to pale yellow, 4.5–5.5 cm, with crimson nectar pouches at base inside; lobes 8(–10); stamens 18–20, unequal, filaments densely puberulent at base; ovary ca. 10 mm, densely pale brown-tomentose, eglandular; style glabrous, stigma large and discoid. Peduncle 6–6.5 cm. Capsule large and woody, cylindric, slightly curved, 40–70 × 14–17 mm, densely rusty-tomentose. Fl. Apr–May, fr. Aug–Oct.
Coniferous forests in alpine regions, Rhododendron thickets; 2100–3600 m. SE Xizang, W Yunnan [NE Myanmar].