A genus of trees or shrubs commonly known as Maple.

Maples are variously classified in a family of their own, the Aceraceae, or together with the Hippocastanaceae included in the family Sapindaceae. Modern classifications, including the Angiosperm Phylogeny Group system, favour inclusion in Sapindaceae. The type species of the genus is Acer pseudoplatanus (Sycamore Maple).

There are approximately 125 species, most of which are native to Asia, with a number also appearing in Europe, northern Africa, and North America.

Maples are mostly trees growing to 10-45 metres (30-145 ft) in height. Others are shrubs less than 10 metres tall with a number of small trunks originating at ground level. Most species are deciduous, but a few in southern Asia and the Mediterranean region are evergreen. Most are shade-tolerant when young, and are often late-successional in ecology; many of the root systems are typically dense and fibrous. A few species, notably Acer cappadocicum, frequently produce root sprouts, which can develop into clonal colonies.

Maples are distinguished by opposite leaf arrangement. The leaves in most species are palmate veined and lobed, with 3-9 (rarely to 13) veins each leading to a lobe, one of which is central or apical. A small number of species differ in having palmate compound, pinnate compound, pinnate veined or unlobed leaves. Several species, including Acer griseum (Paperbark Maple), Acer mandshuricum (Manchurian Maple), Acer maximowiczianum (Nikko Maple), and Acer triflorum (Three-flowered Maple), have trifoliate leaves.

Maple flowers are green, yellow, orange or red. Though individually small, the effect of an entire tree in flower can be striking in several species. Some maples are an early spring source of pollen and nectar for bees.

The distinctive fruit are called samaras or "maple keys". These seeds, or 'whirlybirds,' occur in distinctive pairs each containing one seed enclosed in a "nutlet" attached to a flattened wing of fibrous, papery tissue.

from: Wikiepedia