Acer pilosum Maxim.

Trees small, ca. 5 m tall, andromonoecious. Branchlets slender, glabrous; winter buds brownish, small, densely ciliate along margin. Leaves deciduous; petiole 1.5-3 cm, glabrous; leaf blade abaxially pale green, 3-6(-8) × 2.5-7(-12) cm, papery or nearly leathery, abaxially villous on veins and ciliate along margin when young, soon glabrescent, adaxially glabrous, primary veins 3, lateral veins 8 or 9 pairs, base nearly truncate, deeply 3-lobed, sinuses to 5/6-9/10 width of blade; lobes oblong-lanceolate, margin entire or rarely with few serrations apically or with few obtuse teeth, apex obtuse or acute. Inflorescences terminal or lateral, corymbose, glabrous, numerous flowered; peduncles 1-1.5 cm. Sepals 5, ovate, sparsely ciliate along margin. Petals 5, linear-oblong, glabrous. Stamens 5 or 6, in fertile flowers nearly as long as sepals; filaments glabrous. Disk lobed, extrastaminal. Ovary puberulent in fertile flowers, rudimentary in staminate flowers; style glabrous; stigmas papillose, revolute. Fruit greenish or brownish yellow; nutlets slightly convex to convex, ca. 6 mm in diam.; wing including nutlet 2-2.5 cm × 8-10 mm, wings spreading acutely to nearly horizontally. Fl. Apr or May, fr. Sep.

Gansu, SW Nei Mongol, SE Ningxia, Shaanxi, Shanxi.

● Forests; 1000-2000 m.