Description from Flora of China
Rhododendron principis Bureau & Franchet var. vellereum (Hutchinson ex Tagg) T. L. Ming.
Small trees, 2–5 m tall; shoots ca. 5 mm in diam., thinly floccose, glabrescent. Petiole 15–20 mm, white-floccose; leaf blade thickly leathery, oblong-elliptic to oblong-lanceolate, 6–12 × 2–4.5 cm; base rounded or cordate; apex obtuse or acute; abaxial surface indumentum silvery-white to gray-yellow, somewhat thick, soft and spongy, surface forming glossy pellicle; adaxial surface glabrous. Inflorescence racemose-umbellate, 10–20-flowered; rachis ca. 10 mm. Pedicel red, 1.5–2 cm, sparsely floccose or glabrescent; calyx lobes 5, ca. 1 mm, shallow, slightly floccose; corolla funnel-campanulate, white, sometimes flushed rose, with purple spots inside, 3.5–4 cm, lobes 5; stamens 10, filaments sparsely puberulent in lower half; ovary ca. 6 × 2.5 mm, 5- or 6-locular, glabrous, sometimes with a few floccose hairs at base; style ca. 2.3 cm, glabrous. Capsule narrowly long-cylindric, sulcate, strongly curved, 23–35 × 4–5 mm, glabrous. Fl. May–Jun, fr. Jul–Sep.
The types of Rhododendron vellereum and R. principis are very similar, differing only in the indumentum on the ovary. The former taxon may not merit any more than subspecific rank.
Coniferous forests, Rhododendron thickets, mountains; 3000–4500 m. SE Qinghai, S Xizang.