Maple

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For other uses, see Maple (disambiguation).
iMaple
Silver Maple (Acer saccharinum) leaves
Silver Maple (Acer saccharinum) leaves
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Sapindales
Family: Sapindaceae
Genus: Acer
L.
Distribution
Distribution
Species

See List of Acer species

Maples are trees or shrubs in the genus Acer. There are approximately 125 species, most of which are native to Asia, but several species also occur in Europe, northern Africa, and North America; for a list, see List of Acer species. 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 Greek 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].

The tree, most notabaly the leaf, gained popular use in the early symbols of Canada. Today, the maple leaf is featured on the Canadian flag and Canadian-related logos.

Contents

[edit] Morphology

Sugar Maple (Acer saccharum) leaves in fall
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Sugar Maple (Acer saccharum) leaves in fall

Maples are mostly trees growing to 10-40 m (30-130 feet) in height. Others are shrubs less than 10 m 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, Manitoba Maple (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.

Red Maple (Acer rubrum) flowers
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Red Maple (Acer rubrum) flowers

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.

Sycamore Maple (Acer pseudoplatanus) seed
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Sycamore Maple (Acer pseudoplatanus) seed

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.[1].

[edit] 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.

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 Rhystima species and mildew caused by Uncinula species, though these diseases do not usually have an adverse effect on the trees' long-term health[2].

[edit] Uses

[edit] Horticulture

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

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.[1]. 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.[1].

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[1].

[edit] Tourism

Autumn colour in the Hodaka Mountains of Japan
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Autumn colour in the Hodaka Mountains of Japan

Many Acer species have bright autumn foliage. 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 Pacific Northwest, it is the spectacular fall colors of the Vine Maple (A. circinatum) that draw tourists and photographers.

Other regions have their own leaf-watching tradition as well. In Japan, the custom of viewing the changing color of maples in the autumn is called "momijigari". Nikko and Kyoto are particularly favoured destinations for this activity.

[edit] Commercial uses

Maples are important as source of syrup and wood. 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.

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 guitar and the 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.

[edit] Symbolism

The flag of Canada depicts a stylized maple leaf and is a prominent national symbol. The maple leaf is also the symbol of the online game MapleStory from Wizet and Nexon.

[edit] References

  1. ^ a b c d e f 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.

[edit] External links

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