Acer (maple) is a genus of trees or shrubs. They 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. There are approximately 125 species, most of which are native to Asia, but several species also occur in Europe, northern Africa, and North America.

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. The type species of the genus is Acer pseudoplatanus (Sycamore Maple).^[1]

Morphology

Acer saccharum (Sugar Maple)

Acer circinatum (Vine Maple) leaves showing the palmate veining typical of most species

Acer rubrum (Red Maple) flowers

Acer platanoides (Norway Maple) samaras

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. Children often call them "helicopters" due to the way that they spin as they fall. Seed maturation is usually in a few weeks to six months after flowering, with seed dispersal shortly after maturity. However, one tree can release hundreds of the seeds at a time. Depending on the species, the seeds can be small and green to yellow and big with thicker seed pods. The green seeds are released in pairs, sometimes with the stems still connected. The yellow seeds are released individually and almost always without the stems. Most species require stratification in order to germinate, and some seeds can remain dormant in the soil for several years before germinating.^[1]

The genus is subdivided by its morphology into a multitude of sections and subsections. ^[3]

Pests and diseases

Rhytisma acerinum fungus on Acer pseudoplatanus leaf

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 rarely be caused 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.^[4]

Uses

Horticulture

A red Maple tree between many pine trees.

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

Cultivars

Numerous maple cultivars have been selected for particular characteristics can be propagated only by asexual reproduction such as cuttings, tissue culture, budding or grafting. Acer palmatum (Japanese Maple) 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. Maple is also a key wood in the construction of percussion instruments like drum kits. Some of the best drum building companies like DW (Drum Workshop) use maple extensively throughout their mid-pro range.^[1]

Bonsai

Bonsai "Roter Federahorn"

Collections

Acer griseum is widely grown for its decorative bark

Tourism

Many maples 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. In addition, in Korea, the same viewing activity is called "Danpung-Nori" and Seoraksan and Naejang-san mountains are very famous places for it.

The particularly spectacular fall colours of the Acer rubrum (Red Maple) 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 Quebec, Vermont, New Hampshire and Western Massachusetts. In the American Pacific Northwest and British Columbia it is the spectacular fall colours of Acer circinatum (Vine Maple) 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 taffy. It takes about 40 litres of Sugar Maple sap to make a litre of syrup. 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

A bench made of highly-figured maple wood

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.

Tonewood

Maple is considered a tonewood, or a wood that carries sound waves well, and is used in numerous musical instruments. Maple is harder and has a brighter sound than Mahogany, which is the other major tonewood used in instrument manufacture.

Most drums are made from maple. From the 70s to the 90s, maple drum kits were a vast majority of all drum kits made. In recent years, Birch has become popular for drums once again. Electric guitar necks are commonly made from maple. The necks of the Fender Stratocaster and Telecaster were originally an entirely maple one piece neck, but later were also available with rosewood fingerboards. Maple fingerboards have a brighter sound than rosewood.

The tops of Gibson's Les Paul guitar are made from carved maple. Many Les Pauls have quilted or flamed maple tops, and these models are particularly prized by players and collectors. Very few solid body guitars are made entirely from maple, as it is considered too heavy. Many guitars do, however, have maple tops or veneers. Gibson uses laminated maple in the manufacture of many of its semi-hollowbody guitars.

Maple is also used to make bassoons and double basses.

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,^[5] Vermont,^[6] Wisconsin^[7] and West Virginia.^[8] The Red Maple was adopted by Rhode Island ^[9]as their official state tree.

<gallery> Image:Acer cappadocicum spring.jpg|Acer cappadocicum (Cappadocian Maple) Image:Acer carpinifolium.jpg|Acer carpinifolium leaves Image:Paperbark Maple Acer griseum Leaves Closeup 2856px.jpg|Acer griseum compound (trifoliate) leaf Image:BigleafMaple 0304.jpg|Acer macrophyllum flowers and young leaves Image:Acer laevigatum 3.jpg|Acer laevigatum leaves and fruit Image:Acer sempervirens leaves.jpg|Acer sempervirens foliage Image:Acer ginnala.jpg|Acer ginnala foliage Image:redmaple.jpg|Acer rubrum trees in autumn Image:TenryujiMomiji.jpg|Acer palmatum trees and bamboo in Japan Image:Bi-colored Maple Tree.jpg|Acer grandidentatum in autumn colour Image:Maple leaf Fcb981.JPG|Acer platanoides leaf Image:Red maple leaf.jpg|Acer palmatum leaf in autumn </gallery>

References

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