Description from Flora of China
Acer tonkinense H. Lecomte subsp. fenzelianum (Handel-Mazzetti) A. E. Murray.
Trees 7-20 m tall. Bark gray or blackish gray. Branchlets slender, densely tomentose; lenticels brown, rounded. Leaves deciduous; petiole 2-3 cm, densely yellowish tomentose; leaf blade thickly membranous or subleathery, abaxially glabrous except densely tomentose on main veins, adaxially glabrous except slightly pubescent at base of veins, primary veins 3, from base to apex of blade, reticulate veins conspicuous abaxially, base rounded or broadly cuneate, shallowly 3-lobed or 3-dentate, rarely unlobed, sinuses to 1/5-1/4 width of blade; lobes triangular-ovate, apex acuminate. Inflorescence corymbose, short, few flowered. Flowers unknown. Infructescence usually gray or yellow tomentose, rarely glabrescent. Fruit purplish yellow, 4-6; nutlets convex, oblong, 1-1.2 cm × 6-8 mm, persistently villous, veined; wing including nutlet 3.5-3.8 × ca. 1.7 cm; wings spreading obtusely, pubescent or glabrescent. Fr. Sep.
Forests, valleys; 1100-1700 m. S Yunnan [Vietnam].