Acer is a genius of trees or shrubs commonly known as maple. The genus is classified as member of the family Sapindaceae. Most species are deciduous and many are renowned for their autumn leaf colour, but a few are evergreen.
The leaves in most species are palmate veined and lobed, with 3 to 9 (rarely to 13) veins each leading to a lobe, one of which is central or apical. They are distinguished by opposite leaf arrangement.
The distinctive fruit are called samaras, "maple keys", "helicopters", "whirlybirds" or "polynoses". These seeds occur in distinctive pairs each containing one seed enclosed in a "nutlet" attached to a flattened wing of fibrous, papery tissue. They are shaped to spin as they fall and to carry the seeds a considerable distance on the wind. People often call them "helicopters" due to the way that they spin as they fall. Some seeds can remain dormant in the soil for several years before germinating.
A maple leaf is on the coat of arms of Canada and is on the Canadian flag. The maple is a common symbol of strength and endurance and has been chosen as the national tree of Canada.
Maples are important as source of syrup and wood. Dried wood is often used for the smoking of food. They are also cultivated as ornamental trees.
Leaf peeping is an informal term in the US for the activity in which people travel to view and photograph the fall foliage in areas where foliage changes colors in autumn, particularly in New England, close to canada. A similar custom in Japan is called momijigari.