69. Rhododendron invictum I. B. Balfour & Farrer, Notes Roy. Bot. Gard. Edinburgh. 10: 116. 1917.
绝伦杜鹃 jue lun du juan
Shrubs, evergreen, 1.2–2.2 m tall; young shoots scaly, sparsely pubescent. Petiole 8–10 mm, scaly, sparsely pubescent; leaf blade elliptic or oblong-elliptic, 4–5 × 2–2.5 cm; base cuneate to obtuse; apex obtuse or acute; abaxial surface scales ca. 1.5 × their own diameter apart, dimorphic, golden yellow; adaxial surface deep green, without scales, pubescent along midrib. Inflorescence terminal, umbellate, 2- to many-flowered; rachis 1–2 mm. Pedicel shorter than corolla, 0.6–0.8 cm, scaly, glabrous; calyx 5-lobed; lobes ca. 1 mm, ovate or triangular, scaly abaxially and on margin, pubescent; corolla funnelform-campanulate or campanulate, 5-lobed, purple, 2.2–2.6 × ca. 2.6 cm, outer surface scaly, puberulous along the adaxial suture, otherwise glabrous, inner surface densely pubescent at base; stamens 10, unequal, 1.2–2.5 cm, as long as or slightly longer than corolla; filaments densely villous below; ovary 5-locular, densely scaly, pubescent at apex; style erect, longer than corolla, scales absent, pubescent at base. Capsule ca. 12 × 4 mm, scaly.
Thickets on high mountains; 2400–2800 m. S Gansu.