Trees small, 8-12 m tall, androdioecious, sometimes andromonoecious. Bark gray, smooth. Branchlets purplish brown at end of first year, later becoming light grayish brown, glabrous, marked by numerous lenticels; winter buds ovoid, scales 4 or 6 pairs, imbricate, lustrous brown, ciliate. Leaves deciduous, trifoliolate; petiole 3-8 cm, densely pilose near articulation of petiolules; leaflet blades elliptic-oblong to oblong-lanceolate, (5-)8-15 × 2-6 cm, papery, abaxially glaucous, sparsely pubescent on midvein, with tufts of hairs at vein axils, adaxially glabrous, veins 8-10, apex acuminate; middle petiolules 1.5-2 cm, glabrescent; lateral petiolules 5-8 mm, glabrescent; lateral leaflets obliquely rounded at base, margin remotely dentate. Inflorescence corymbiform-racemose, on leafy or rarely leafless branches, glabrous, 8-12-flowered; peduncles 8-16 mm. Pedicel 8-12 mm, slender, glabrous. Staminate flowers: sepals 5(or 6), ovate or lanceolate, ca. 6 mm; petals 5(or 6), obovate, ca. as long as sepals; stamens 10-16, nearly 2 × as long as petals; filaments glabrous; rudimentary ovary small, pilose; disk glabrous, extrastaminal. Fruit in short glabrous racemes, purplish or brownish; nutlets 6-7 mm, strongly convex; wing including nutlet 2-5.5 cm × ca. 7 mm, wings spreading erectly. Fl. Apr-May, fr. Sep.
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