American Sweetgum
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American Sweetgum (Liquidambar styraciflua), also known as Redgum, is a deciduous tree in the genus Liquidambar native to warm temperate areas of eastern North America. It occurs in the United States from southern New York west to southern Missouri and east Texas and south to central Florida, and in Mexico from southern Nuevo León south to Chiapas, as well as in Guatemala. In the United States it occurs at low to moderate altitudes, while in Mexico and Guatemala it grows at high altitudes in mountains where the climate is more temperate.
It is a medium-sized to large tree, growing to 20-35 m (exceptionally 41 m) tall, with a trunk up to 2 m diameter. The leaves are palmately lobed, 7-19 cm (rarely to 25 cm) long and broad and with a 6-10 cm petiole, looking somewhat similar to those of some maples. They have five sharply-pointed lobes, but are easily distinguished from maples in being arranged alternately, not in opposite pairs. They are a rich dark green and glossy, and in most cases turn brilliant orange, red and purple colors in the autumn. A small percentage of trees are evergreen or semi-evergreen, with negligible fall color.
The male and female inflorescences are on different branches of the same tree. The fruit, popularly nick-named a "gumball" or "birball", is a hard, dry, globose, compound fruit 2.5-4 cm in diameter and composed of numerous (20-50) capsules. Each capsule has a pair of terminal spikes, and contains one to two small seeds.
Uses
American Sweetgum is a popular ornamental tree, grown for its intense fall colors, but it also has some drawbacks. The wood is brittle and the tree drops branches easily in storms. The spiked "gumballs" are somewhat unpleasant to walk on, and their profusion can smother a lawn unless removed.
As well as in its native area, it has been introduced to many parts of the world, including Argentina, Australia, Chile, Europe, Hawaii, New Zealand, South Africa, Uruguay and Zimbabwe. In the United States, it is especially popular in California, where it has escaped from cultivation. In Florida, it is sold at least as far south as Lake Worth. In Canada, it is commonly cultivated in cities of western British Columbia such as Victoria and Vancouver. It also grows well at Toronto and Niagara Falls. Farther east, it grows as a root-hardy shrub in Ottawa and Montreal. It grows best in moist, acidic loam or clay soil, and tolerates poor drainage. Salt tolerance is moderate. Chlorosis can develop on alkaline soil, especially where organic matter is low.
The wood is very compact and fine-grained, the heartwood being reddish, and, when cut into planks, marked transversely with blackish belts; it is used for veneer and pulpwood, but is poor for timber or fuel. Being readily dyed black, it is sometimes used instead of ebony for picture frames, and other similar uses, but it is too liable to decay for outdoor work.
The earliest record of the tree appears to be in a Spanish work by F. Hernandez, published in 1651, in which he describes it as a large tree producing a fragrant gum resembling liquid amber, whence the name. In Ray's Historia Plantarum (1686) it is called Styrax liquida. It was introduced into Europe in 1681 by John Banister, the missionary collector sent out by Bishop Compton, who planted it in the palace gardens at Fulham.
The gum resin, also known as liquid amber or copalm balsam, yielded by this tree has no special medicinal virtues, being inferior in therapeutic properties to many others of its class. It is a kind of native balsam, or resin, like turpentine. It may be clear, reddish or yellow, with a pleasant smell like ambergris. As it grows older, it hardens into a solid form, which historically was shipped to other countries in barrels. It was reputed an excellent balsam for mollifying and consolidating, and good against sciatica, weakness of the nerves, etc. Mixed with tobacco, the gum was once used for smoking at the court of the Mexican emperors. It was long used in France as a perfume for gloves and other such items. It is mainly produced in Mexico, little being obtained from trees growing in higher latitudes of North America, or in England.
An American Sweetgum will be featured as part of the Memorial Grove at the World Trade Center Memorial, with installation set for fall 2008 and spring 2009 [link].
- Selected cultivars
- 'Burgundy' – dark red to purple fall colors may persist through winter.
- 'Clydesform' - sold as Emerald Sentinel®; columnar or narrowly pyramidal; slow growth to 9 meters; yellow-orange fall colors.
- 'Festival' – columnar; pale green summer leaves; bright fall hues of yellow, pink and red; less hardy than most.
- 'Goduzam' (Gold Dust) – variegated; pink to red-purple in fall.
- 'Grazam' – pyramidal, with glossy leaves. Orange, red and purple fall colors.
- 'Gumball' – dwarf shrubby cultivar seldom more than 2 meters tall. Purple-red fall color.
- 'Moraine' – upright, rounded form, fast growth, red fall color, hardy to −30 °C.
- 'Palo Alto' – various shades of red in fall; best in California.
- 'Parasol' – develops rounded crown; mature height 10 meters; deep red fall color.
- 'Rotundiloba' – sterile cultivar with rounded lobes on leaves.
- 'Slender Silhouette' - very narrow columnar form.
- 'Worplesdon' – cutleaf cultivar with orange, red and purple fall colors.
References and external links
- Americas Regional Workshop (Conservation & Sustainable Management of Trees, Costa Rica, November 1996) (1998). [Liquidambar styraciflua]. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006.
- Flora of North America: [genus account] and [species account]
- [Liquidambar styraciflua images at bioimages.vanderbilt.edu]
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