Liquidambar styraciflua

Liquidambar styraciflua
Conservation status
Least Concern (IUCN 2.3)
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Core eudicots
Order:	Saxifragales
Family:	Altingiaceae
Genus:	Liquidambar
Species:	L. styraciflua
Binomial name
Liquidambar styraciflua L.

Liquidambar styraciflua, commonly called the American sweetgum, sweet-gum,^[1] alligator-wood,^[1] American-storax,^[1] bilsted,^[2] red-gum,^[1] satin-walnut,^[1] or star-leaved gum,^[2] is a deciduous tree in the genus Liquidambar native to warm temperate areas of eastern North America and tropical montane regions of Mexico and Central America. A popular ornamental tree in temperate climates, it is recognizable by the combination of its five-pointed star-shaped leaves and its hard, spiked fruits. It is currently classified in the plant family Altingiaceae, but was formerly considered a member of the Hamamelidaceae.

Names

This plant's genus name Liquidambar is explained by botanist M. L. Fernald as "a mongrel name, from [the Latin] liquidus, fluid, and the Arabic ambar, amber, in allusion to the fragrant terebinthine juice or gum which exudes from the tree."^[3] Its specific epithet styraciflua is an old generic name meaning flowing with styrax (a plant resin).^[3][4] The names "storax" and "styrax" have long been confusingly applied to the aromatic gum or resin of this species, that of L. orientalis of Turkey, and to the resin better known as benzoin resin from various tropical trees in the genus Styrax.

The common name "sweet gum" refers to the species' "sweetish gum",^[5] contrasting with the black gum (Nyssa sylvatica), only distantly related, with which the sweet gum overlaps broadly in range. The species is also known as the "red gum", for its reddish bark.^[5]

Description

Summer foliage of Liquidambar styraciflua

Autumn foliage and fruit of Liquidambar styraciflua

Small branches with edgewise plates of bark

Liquidambar styraciflua is a medium-sized to large tree, growing to 20–35 m (65–115 ft), rarely to 41 m (135 ft) tall, with a trunk up to 2 m (6 ft) in diameter. Trees may live to 400 years.^[4]

The leaves usually have five (but sometimes three or seven) sharply pointed palmate lobes. They are 7–19 cm (rarely to 25 cm) long and broad, with a 6–10 cm petiole. The rich dark green, glossy leaves generally turn brilliant orange, red, and purple colors in the autumn.

This autumnal coloring has been characterized as not simply a flame, but a conflagration. Its reds and yellows compare to that of the maples (Acer), and in addition it has the dark purples and smoky browns of the ash (Fraxinus).^[6] However, in the northern part of its range, and where planted in yet colder areas, the leaves are often killed by frost while still green. On the other hand, in the extreme southern or tropical parts of its range, some trees are evergreen or semi-evergreen, with negligible fall color.

The male and female inflorescences are separate on the same tree.

The distinctive compound fruit is hard, dry, and globose, 2.5–4 cm in diameter, composed of numerous (40-60) capsules. Each capsule, containing one to two small seeds, has a pair of terminal spikes (for a total of 80-120 spikes). When the fruit opens and the seeds are released, each capsule is associated with a small hole (40-60 of these) in the compound fruit.

Fallen, opened fruits are often abundant beneath the trees; these have been popularly nicknamed "ankle biters" or "ankle twisters (in California),^{[citation needed]} "burr balls",^[4] "bommyknockers",^{[citation needed]} "conkleberrys",^{[citation needed]} "cukoo-birs",^{[citation needed]} "gumballs",^{[citation needed]} "monkey balls",^{[citation needed]} "pinkelponkers" (in North Carolina),^{[citation needed]} "space bugs",^{[citation needed]} and "sticky balls".^{[citation needed]}

Another distinctive feature of the tree is the peculiar appearance of its small branches and twigs. The bark attaches itself to these in plates edgewise instead of laterally, and a piece of the leafless branch with the aid of a little imagination readily takes on a reptilian form; indeed, the tree is sometimes called Alligator-wood.^[6]

The roots are fibrous; juices are balsamic.^{[citation needed]}

The tree secretes an aromatic fluid, which when processed is called styrax.^[4]

Additional characteristics of Liquidambar styraciflua include:

• Leaves: Alternate, three to five inches long, three to seven inches broad, lobed, so as to make a star-shaped leaf of five to seven divisions, these divisions acutely pointed, with glandular serrate teeth. The base is truncate or slightly heart-shaped. They come out of the bud plicate, downy, pale green, when full grown are bright green, smooth, shining above, paler beneath. In autumn they vary in color from yellow through crimson to purple. They contain tannin and when bruised give a resinous fragrance. Petioles long, slender, terete. Stipules lanceolate, acute, caducous.^[6]
• Flowers: March to May, when leaves are half grown; monoecious, greenish. Staminate flowers in terminal racemes two to three inches long, covered with rusty hairs; the pistillate in a solitary head on a slender peduncle borne in the axil of an upper leaf. Staminate flowers destitute of calyx and corolla, but surrounded by hairy bracts. Stamens indefinite; filaments short; anthers introrse. Pistillate flowers with a two-celled, two-beaked ovary, the carpels produced into a long, recurved, persistent style. The ovaries all more or less cohere and harden in fruit. Ovules many but few mature.^[6]
• Fruit: Multicapsular spherical head, an inch to an inch and a half in diameter, hangs on the branches during the winter. The woody capsules are mostly filled with abortive seeds resembling sawdust.^[6]
• Bark: Light brown tinged with red, deeply fissured, ridges scaly. Branchlets pithy, many-angled, winged, at first covered with rusty hairs, finally becoming red brown, gray or dark brown.^[6]
• Winter buds: Yellow brown, one-fourth of an inch long, acute. The inner scales enlarge with the growing shoot, becoming half an inch long, green tipped with red.^[6]

While the starry five-pointed leaves of Liquidambar resemble those of some maples (Acer), such as the Japanese maple (Acer palmatum), the sugar maple (Acer saccharum), and the Norway maple (Acer platanoides), Liquidambar is easily distinguished from Acer by its glossy, leathery leaves that are positioned singly (alternate), not in pairs (opposite) on the stems. The long-stemmed fruit balls of Liquidambar resemble those of the American sycamore or buttonwood (Platanus occidentalis), but are spiny and remain intact after their seeds are dispersed; the softer fruits of Platanus disintegrate upon seed dispersal.

Distribution

Sweetgum is one of the most common hardwoods in the eastern United States, where it occurs naturally at low to moderate altitudes from southwestern Connecticut south to central Florida, and west to Illinois, southern Missouri, and eastern Texas, but not colder areas of Appalachia or the Midwestern states.

The species also occurs in Mexico from southern Nuevo León south to Chiapas, as well as in Guatemala, El Salvador, Nicaragua, and Honduras. In Mexico and Central America, it is a characteristic plant of cloud forests, growing at middle elevations in various mountainous areas where the climate is humid and more temperate.

Fossil record

An ancestor of Liquidambar styraciflua is known from Tertiary-aged fossils in Alaska, Greenland, and the mid-continental plateau of North America, much further north than Liquidambar now grows. A similar plant is also found in Miocene deposits of the Tertiary of Europe.^[6]

Uses

Liquidambar styraciflua is valued as a cultivated ornamental tree, and in its natural habitats, as a timber tree and for its dramatically colored fall foliage. The resin for which it was named also has various uses.

Cultivation

Liquidambar styraciflua is a popular ornamental tree, cultivated for its distinctive foliage and intense fall colors. It is commonly grown throughout its native North American range as well as many other parts of the world, including Argentina, Australia (as far north as Brisbane), Brazil, California, southernmost Canada, Chile, Europe, Hawaii, Namibia, New Zealand, South Africa, Uruguay and Zimbabwe. The species grows best in moist, acidic loam or clay soil, and tolerates poor drainage. Its salt tolerance is moderate. Chlorosis can develop on alkaline soil, especially where organic matter is low.

In the United States, it is popular in California, where it is known as "liquid amber" and has occasionally escaped from cultivation there. In Florida, it is sold at least as far south as Palm Beach County. In the Tri-State Region of New York, New Jersey, and Connecticut, it is locally native but not commonly planted.

Liquidambar styraciflua is commonly cultivated in Canada and the northernmost United States well north of its native range. For example, it grows well in Victoria and Vancouver in western British Columbia, in Toronto and Niagara Falls in southern Ontario, in southern New England northward to southeastern New Hampshire, and in the Chicago, Illinois, area, with its warmer microclimate around southern Lake Michigan. Farther northeastward, in Ottawa, Ontario, and in Montreal, Quebec, the species is sometimes grown as a root-hardy shrub.

Among the many cultivars of Liquidambar styraciflua are:

• 'Burgundy' – dark red to purple fall colors may persist through winter.^{[citation needed]}
• 'Clydesform' - columnar or narrowly pyramidal; slow growth to 9 meters; yellow-orange fall colors; also sold as 'Emerald Sentinel'^{[citation needed]}
• 'Festival' – columnar; pale green summer leaves; bright fall hues of yellow, pink and red; less hardy than most.^{[citation needed]}
• 'Goduzam' – variegated; pink to red-purple in fall; also called 'Gold Dust'^{[citation needed]}
• 'Grazam' – pyramidal, with glossy leaves. Orange, red and purple fall colors.^{[citation needed]}
• 'Gumball' – dwarf shrubby cultivar seldom more than 6 feet (2 meters) tall, with purple-red fall color.^{[citation needed]}
• 'Moraine' – upright, rounded form, fast growth, red fall color, hardy to −30 °C.^{[citation needed]}
• 'Palo Alto' – various shades of red in fall; best in California.^{[citation needed]}
• 'Parasol' – develops rounded crown; mature height 10 meters; deep red fall color.^{[citation needed]}
• 'Rotundiloba' – sterile cultivar with rounded lobes on leaves, originally discovered in North Carolina in the 1930s.^{[citation needed]}
• 'Slender Silhouette' - very narrow columnar form.^{[citation needed]}
• 'Worplesdon' – cutleaf cultivar with orange, red and purple fall colors.^{[citation needed]}

Fruit of Liquidambar styraciflua after seed dispersal

As an ornamental tree, the species has some drawbacks:

• The wood is brittle and the tree drops branches easily in storms.
• The long-persisting fallen spiked fruits can be unpleasant to walk on; sweet gum is banned in some places for this reason.^[4] In abundance, they can leave a lawn lumpy.
• Branches may have ridges or "wings" that cause more surface area, increasing weight of snow and ice accumlation on the tree.

A Liquidambar styraciflua tree will be included in the Memorial Grove at the World Trade Center Memorial in New York, with installation set for fall 2008 and spring 2009 [1].

Bark of mature tree of Liquidambar styraciflua in Hemingway, South Carolina

Wood

Sweetgum (Liquidambar styraciflua) is one of the most important commercial hardwoods in the Southeastern United States. Its wood is bright reddish brown (with the sapwood nearly white), heavy, straight, satiny, and close-grained, but not strong. It takes a beautiful polish, but warps badly in drying. The wood has a specific gravity of 0.5910, with a weight of 36.83 lbs per cubic foot. It is too liable to decay for outdoor use.^[6]

The tree's handsome hard wood is put to a great many uses, including veneer for plywood. The wood is very compact and fine-grained, the heartwood being reddish, and, when cut into planks, marked transversely with blackish belts. Sweetgum is used principally for lumber, veneer, plywood, slack cooperage, railroad ties, fuel, and pulpwood. The lumber is made into boxes and crates, furniture, cabinets for radios, televisions, and phonographs, interior trim, and millwork. The veneer and plywood, (typically backed with some other kind of wood which shrinks and warps less) are used for boxes, pallets, crates, baskets, and interior woodwork. It was formerly used in the interior finish of railroad sleeping cars. Being readily dyed black, it is sometimes substituted for ebony for such uses as inexpensive picture frames.^[6][7]

Resin

The tree's gum resin, also known as liquid amber or copalm balsam, is a kind of native balsam, or resin, resembling turpentine. It may be clear, reddish, or yellow, with a pleasant smell like ambergris. As the resin ages, it solidifies, the form in which it was historically exported in barrels. The resin is produced by stripping, boiling, and pressing the tree's bark.^[4] A similar resin, known as styrax, is produced from another species of Liquidambar, the oriental sweet gum, L. orientalis, of the eastern Mediterranean, especially Turkey, the original source of the chemical styrene from which

The resin was reputed to be an excellent balsam for mollifying and consolidating,^{[citation needed]} and good against such conditions as sciatica and weakness of the nerves.^{[citation needed]} The Aztecs believed styrax to have medicinal properties;^[4] mixed with tobacco, the gum was once used for smoking at the court of the Mexican emperors.^{[citation needed]} Styrax has also been used as a perfume fixative;^[4] it was long used in France as a perfume for such items as gloves.^{[citation needed]} However, the resin is now said to have no special medicinal virtues, being inferior in therapeutic properties to many others of its class.^{[citation needed]}

The resin is now mainly produced in Mexico.^{[citation needed]}

The hydrocarbon styrene is named for Levant styrax from the closely related species Liquidambar orentalis (Oriental sweetgum) of Turkey and adjacent areas, from which it was first isolated.^{[citation needed]} Industrially produced styrene is now used to produce polystyrene plastics, including Styrofoam^TM.

History

The earliest known published record of Liquidambar styraciflua is in a work by Spanish naturalist Francisco Hernández published posthumously in 1651, in which he describes the species as a large tree producing a fragrant gum resembling liquid amber, whence the genus name Liquidambar. In Ray's Historia Plantarum (1686) it is called Styrax liquida.

The species 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 in London, England.

Gallery

• 

  Immature fruit showing the paired capsule spikes

• 

  Liquidambar styraciflua tree cultivated at Keokea, Maui, Hawaii

• 

  Leaves of Liquidambar styraciflua at the Texas A&M University in College Station, Texas.

• 

  Liquidambar styraciflua at the Texas A&M University in College Station, Texas.

• 

  Autumnal color of Liquidambar styraciflua at the parc de Rentilly in France.

• 

  Liquidambar styraciflua in bloom at Clear Creek Park in Crawford County, Arkansas

• 

  Liquidambar styraciflua showing fall colors in West Point, New York

References

1. ^ ^{a b c d e} "USDA GRIN taxonomy". http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?22379. 
2. ^ ^{a b} Small, J.K. (1933). Manual of the southeastern flora: being descriptions of the seed plants growing naturally in Florida, Alabama, Mississippi, eastern Louisiana, Tennessee, North Carolina, South Carolina and Georgia. Chapel Hill, N.C.: University of North Carolina Press. ISBN 0028524101 / 0-02-852410-1. 
3. ^ ^{a b} Fernald, Merritt Lyndon (1950). Gray's Manual of Botany (8th ed.). New York: American Book Company. 
4. ^ ^{a b c d e f g h} "Liquidambar styraciflua: American sweet gum". Cal Poly Plant Conservatory. http://www.plantconservatory.calpoly.edu/Tree/Liquidambar_styraciflua.html. Retrieved 26 July 2011. 
5. ^ ^{a b} Werthner, William B. (1935). Some American Trees: An intimate study of native Ohio trees. New York: The Macmillan Company. pp. xviii + 398 pp.. 
6. ^ ^{a b c d e f g h i j} Keeler, Harriet L. (1900). Our Native Trees and How to Identify Them. New York: Charles hi Scriber's Sons. pp. 160–164. 
7. ^ Kormanik, Paul P. "Liquidambar styraciflua L.—Sweetgum" from Silvics of North America: Volume 2:Hardwoods. Agriculture Handbook 654. U.S. Department of Agriculture, Forest Service, Washington, D.C. 1965

 This article incorporates content from the 1728 Cyclopaedia, a publication in the public domain.

External links

• American Sweetgum Trees
• Americas Regional Workshop (Conservation & Sustainable Management of Trees, Costa Rica, November 1996) (1998). Liquidambar styraciflua. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 12 May 2006.
• Flora of North America: genus account and species account
• USDA Plants Profile: Liquidambar styraciflua
• USFS Silvic Manual: Liquidambar styraciflua
• USGS Species Distribution Maps: Liquidambar styraciflua (pdf file).
• Liquidambar styraciflua images at bioimages.vanderbilt.edu
• Interactive Distribution Map for Liquidambar styraciflua