Description from Flora of China
Acer oblongum Wallich ex Candolle var. biauritum W. W. Smith; A. oblongum var. erythrocarpum H. Léveillé; A. paxii var. semilunatum W. P. Fang.
Trees evergreen, ca. 15 m tall, andromonoecious. Bark brown. Branchlets slender, glabrous; winter buds ellipsoid; scales brownish, ciliate along margin. Petiole 2-5 cm, glabrous; leaf blade ovate, obovate, or suborbicular, 5-11 × 2-6 cm, leathery or thickly leathery, abaxially glaucous, adaxially glabrous and smooth, primary veins 3, base rounded or broadly cuneate, margin entire or occasionally 3-lobed toward apex, undivided leaves also on same tree. Inflorescence terminal on leafy branchlets, corymbose, 3-4 cm wide, numerous flowered. Pedicel slender, glabrous. Sepals 5, glabrous. Petals 5, white, linear-lanceolate. Stamens 8; filaments glabrous. Disk glabrous, extrastaminal. Ovary white tomentose. Fruit greenish yellow; nutlets strongly convex, globose, ca. 8 × 6 mm, wings spreading variously. Fl. Mar, fr. Aug.
● Alpine forests; 1500-2500 m. C and N Guangxi, Guizhou, SW Sichuan, NW Yunnan.