430. Rhododendron sperabile I. B. Balfour & Farrer, Notes Roy. Bot. Gard. Edinburgh. 13: 297. 1922.
纯红杜鹃 chun hong du juan
Shrubs, upright, 1–2 m tall, branches ca. 3.5 mm in diam. below inflorescence, with whitish stellate tomentum intermixed with setose-glands. Petiole 10–15 mm, densely whitish tomentose and setulose-glandular; leaf blade leathery, elliptic to lanceolate, or narrowly oblong, 6.7–11.5 × 1.5–3.5 cm; base obtuse to rounded; margin revolute; apex acute to rounded; abaxial surface epidermis glaucous-papillate, whitish to cinnamon continuously tomentose, hairs dendroid, glandular setae on midrib; adaxial surface green, whitish tomentose and glandular-hairy when young, glabrescent, midrib grooved adaxially, lateral veins 10–12-paired, deeply impressed adaxially. Inflorescence umbellate, 4- or 5-flowered; rachis 2–3 mm, tomentose. Pedicel 1–2 cm, whitish stellate-tomentose and setulose-glandular; calyx cupular; lobes 5, 1–3 mm, glandular-ciliate; corolla tubular-campanulate, fleshy, crimson, 3–3.7 cm, with 5 nectar pouches, glabrous; lobes 5, rounded, ca. 1.3 × 1.6 cm, emarginate; stamens 10, filaments glabrous; ovary conoid, tapering into style ca. 6 mm, densely tomentose and glandular-setulose; style glabrous. Capsule cylindric, curved, ca. 15 × 3.5 mm. Fl. Apr–May, fr. Oct–Nov.
Thickets, rocky slopes, cliffs; 2600–4200 m. NW Yunnan [NE Myanmar].
Two varieties have been recognized in China. Field observations suggest that var. sperabile is closely allied to, and probably a subspecies of, R. floccigerum, whereas var. weihsiense deserves specific rank.