About 150 species of deciduous or evergreen trees, some small shrubs; leaves opposite, usually simple and palmately lobed and veined, sometimes pinnately compound (e.g., A. negundo), leaf scars crescent shaped; flowers, small, in terminal or axillary clusters, 4-8 stamen, 2 styles or stigma; fruit is winged (samara), usually in joined pairs which separate when shed, one seed per fruit (key).
Taxonomy: The maples (Aceraceae) have long been known to be closely related to the family Sapindaceae. Several taxonomists (including the Angiosperm Phylogeny Group) now include both the Aceraceae and the Hippocastanaceae (horse chestnuts and buckeyes) in the Sapindaceae.
Acer: from the Latin name for the Maple, also meaning sharp, possibly a reference to its use as a lance or its hardwood.