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Trees or shrubs in the genus ''Acer'' are commonly called 'Maples'. There are approximately 125 species, most of which are native to Asia, but several species also occur in Europe, northern Africa, and North America. 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 classification, favour inclusion in Sapindaceae.
The word ''Acer'' is derived from a Latin word meaning "sharp" (referring to the characteristic points on the leaves) and was first applied to the genus by the French botanist Joseph Pitton de Tournefort in 1700.^[1]

Contents

Morphology

Pests and diseases

Uses

Horticulture

Cultivars

Bonsai

Collections

Tourism

Commercial uses

Maple syrup

Timber

Agriculture

Symbolism

Musical instruments

References

See also

External links

Morphology

Maples are mostly trees growing to 10-40 metres (30-130 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.
Maples are distinguished by opposite leaf arrangement. The leaves in most species are palmately veined and lobed, with 3-9 veins each leading to a lobe, one of which is in the middle. A small number of species differ in having palmate compound, pinnate compound, pinnate veined or unlobed leaves.
Several species, including the Paperbark Maple (''Acer griseum''), Manchurian Maple (''Acer mandshuricum''), Nikko Maple (''Acer maximowiczianum''), and Three-flowered Maple (''Acer triflorum''), have trifoliate leaves. One species, Box Elder (''Acer negundo''), has pinnately compound leaves that may be simply trifoliate or may have five, seven, or rarely nine leaflets. One maple, the Hornbeam Maple (''Acer carpinifolium''), has pinnately-veined simple leaves that resemble those of hornbeam.

The flowers are regular, pentamerous, and borne in racemes, corymbs, or umbels. They have five sepals, five petals about 1 to 6 mm long, 12 stamens about 6-10 mm long in two rings of six, and two pistils or a pistil with two styles. The ovary is superior and has two carpels, whose wings elongate the flowers, making it easy to tell which flowers are female. Maples flower in late winter or early spring, in most species with or just after the leaves appear, but in some before them.
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 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. Seed maturation is usually in a few weeks to six months of flowering, with seed dispersal shortly after maturity. Most species require stratification in order to germinate, and some seeds can remain dormant in the soil for several years before germinating.

Pests and diseases

The leaves are used as a food plant for the larvae of a number of Lepidoptera species (see List of Lepidoptera which feed on Maples). Aphids are also very common sap-feeders on maples. In horticultural applications a dimethoate spray will solve this.
Maples are affected by a number of fungal diseases. Several are susceptible to Verticillium wilt caused by ''Verticillium'' species, which can cause significant local mortality. Sooty bark disease, caused by ''Cryptostroma'' species, can kill trees which are under stress due to drought. Death of maples can also be caused more rarely by ''Phytophthora'' root rot and ''Ganoderma'' root decay. Maple leaves in late summer and autumn are commonly disfigured by "tar spot" caused by ''Rhytisma'' species and mildew caused by ''Uncinula'' species, though these diseases do not usually have an adverse effect on the trees' long-term health.^[2]

Uses

Horticulture

''Acer palmatum'' has over 1,000 cultivars. This cultivar is ''A. palmatum'' 'Sango kaku', sometimes called "coralbark maple".

Maples are planted as ornamental trees by homeowners, businesses and municipalities. Norway Maple (''A. platanoides'') is especially popular as it is fast-growing and extremely cold-resistant, though is also an invasive species in some regions. Other maples, especially smaller or more unusual species, are popular as specimen trees.

Cultivars

Numerous maple cultivars have been selected for particular characteristics and can be propagated only by grafting. Japanese Maple (''A. palmatum'') alone has over 1,000 cultivars, most selected in Japan, and many of them no longer propagated or not in cultivation in the western world. Some delicate cultivars are usually grown in pots and rarely reach heights of more than 50-100 cm.

Bonsai

Maples are a popular choice for the art of bonsai. Japanese Maple, Trident Maple (''A. buergerianum''), Amur Maple (''A. ginnala''), Field Maple (''A. campestre'') and Montpellier Maple (''A. monspessulanum'') are popular choices and respond well to techniques that encourage leaf reduction and ramification, but most species can be used.

Collections

Maple collections, sometimes called ''aceretums'', occupy space in many gardens and arboreta around the world including the "five great W's" in England: Wakehurst Place Garden, Westonbirt Arboretum, Windsor Great Park, Winkworth Arboretum and Wisley Garden. In the United States, the aceretum at the Harvard-owned Arnold Arboretum in Boston is especially notable. In the number of species and cultivars, the Esveld Aceretum in Boskoop, Netherlands is the largest in the world.

Tourism

Autumn colour in the Hodaka Mountains of Japan

Many ''Acer'' species have bright autumn foliage, and many countries have leaf-watching traditions. In Japan, the custom of viewing the changing colour of maples in the autumn is called "momijigari". Nikko and Kyoto are particularly favoured destinations for this activity.
The particularly spectacular fall colours of the Red Maple (''A''. ''rubrum'') are a major contributor to the seasonal landscape in southeastern Canada and in New England. Fall tourism is a boon to the economy of this region, especially in Vermont, New Hampshire and Western Massachusetts.
In the American Pacific Northwest, it is the spectacular fall colours of the Vine Maple (''A''. ''circinatum'') that draw tourists and photographers.

Commercial uses

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 plants and have benefits for tourism and agriculture.

Maple syrup

The Sugar Maple (''Acer saccharum'') is tapped for sap, which is then boiled to produce maple syrup or made into maple sugar or maple candy. Syrup can be made from closely-related species as well, but their output is inferior. Sugar maples typically have a lifespan of 300 years.

Timber

Some of the larger maple species have valuable timber, particularly Sugar Maple in North America, and Sycamore Maple in Europe. Sugar Maple wood, often known as "hard maple", is the wood of choice for bowling pins, bowling alley lanes, drums and butcher's blocks. Maple wood is also used for the production of wooden baseball bats, though less often than ash or hickory.
Some maple wood has a highly decorative wood grain, known as flame maple and quilt maple. This condition occurs randomly in individual trees of several species, and often cannot be detected until the wood has been sawn, though it is sometimes visible in the standing tree as a rippled pattern in the bark. Maple is considered a tonewood, or a wood that carries sound waves well, and is used in numerous instruments such as guitars and drums.

Agriculture

As they are a major source of pollen in early spring before many other plants have flowered, maples are important to the survival of honeybees that play a commercially-important role later in the spring and summer.

Symbolism

The flag of Canada depicts a stylized maple leaf and is a prominent national symbol. In the United States, the maple has been adopted by New York,^[3] Vermont,^[4] Wisconsin^[5] and West Virginia.^[6] The red maple was adopted by Rhode Island ^[7]as their official state tree.

Musical instruments

Maple is often used in necks of guitars. It provides resonance and a lighter weight than many other woods used in necks such as rosewood. Also the look of a maple neck is appealing to many guitar players. Maple is also used to make bassoons as well.

References

1. van Gelderen, C.J. & van Gelderen, D.M. (1999). ''Maples for Gardens: A Color Encyclopedia''
2. Phillips, D. H. & Burdekin, D. A. (1992). ''Diseases of Forest and Ornamental Trees''. Macmillan. ISBN 0-333-49493-8.
3. State of New York Dept. of State New York State Symbols. Retrieved Dec. 16 2006.
4. State of Vermont Department of Libraries State Tree. Retrieved Dec. 16 2006.
5. State of Wisconsin State Symbols. Retrieved Dec. 16 2006.
6. Legislature of West Virginia State Symbols. Retrieved Dec. 16 2006.
7. State of Rhode Island, Office of the Secretary of State. History And Facts About The Ocean State. Retrieved Dec. 16 2006.

See also

★ List of Acer species

External links

★ Flora of China draft synopsis of the family Aceraceae

★ Classification of maples

★ UVSC Herbarium - Maples

★ Compare eastern North American maple species at bioimages.vanderbilt.edu

★ Creating Bonsai with Maples

★ Maples