Description from Flora of China
Trees, sometimes shrubs, deciduous or evergreen, andromonoecious, androdioecious, or dioecious (correct from a morphological view; flowers are functionally male or female). Winter buds imbricate or valvate. Leaves opposite, mostly simple and palmately lobed, sometimes leaves pinnately veined and entire or pinnately (7-)11-21-foliolate (Dipteronia), usually estipulate. Inflorescence a corymb, umbel, raceme, or panicle, terminal or lateral. Flowers bisexual (but functionally female) or unisexual, actinomorphic. Sepals (4 or)5, rarely 6, distinct or seldom connate below. Petals (4 or)5, rarely 6, imbricate, distinct, often as sepals, rarely absent. Stamens usually 8, sometimes 4-6 or 10-12; disk extrastaminal, amphistaminal, intrastaminal, or absent. Ovary superior, compressed, usually 2-loculed, with 2 ovules per locule; style usually bifurcate, forming 2 stigmas. Fruit a winged schizocarp, usually a double samara, usually 1-seeded, endosperm absent. Germination epigeous, rarely hypogeous. x = 9 or 13.
The Aceraceae are well represented in E Asia, especially in China. They are sometimes treated within the Sapindaceae; see the discussion under that family (Fl. China 12: 5. 2007).
Fang Wen-pei. 1981. Aceraceae. In: Fang Wen-pei, ed., Fl. Reipubl. Popularis Sin. 46: 66-273.
Two genera and ca. 131 species: the genus Acer is widespread in N temperate and some tropical regions; the genus Dipteronia is endemic to China; two genera (one endemic) and 101 species (63 endemic, three introduced) in China.
(Authors: Xu Tingzhi (徐廷志 Hsu Ting-zhi), Chen Yousheng (陈又生); Piet C. de Jong, Herman J. Oterdoom, Chin-Sung Chang)