Paul P. Kormanik
Sweetgum (Liquidambar styraciflua), also called redgum, sapgum, starleaf-gum, or bilsted, is a common bottom-land species of the South where it grows biggest and is most abundant in the lower Mississippi Valley. This moderate to rapidly growing tree often pioneers in old fields and logged areas in the uplands and Coastal Plain and may develop in a nearly pure stand. Sweetgurn is one of the most important commercial hardwoods in the Southeast and the handsome hard wood is put to a great many uses, one of which is veneer for plywood. The small seeds are eaten by birds, squirrels, and chipmunks. It is sometimes used as a shade tree.
- 1 from the Americas
- 2 from eastern Asia
- 1 from the eastern Mediterranean
Liquidambar styraciflua L.
Mesic pine savannas (MPS-CP), wet pine flatwoods (WPF-T), wet pine savannas (SPS-T, SPS-RF, WLPS, VWLPS).
Occasional (frequent only in areas not recently burned). Apr–May ; Aug–Sep . Thornhill 346, 432 (NCSC). Specimens seen in the vicinity: Old Maple Hill Road: Wilbur 55264 (DUKE!); Sandy Run [ O’Berry ]: Taggart SARU 164 (WNC!). [= RAB, FNA, Weakley]
- leaves are alternately arranged and up to 10cm across with 5–7 deep lobes lending a star-like appearance to them
- they turn deep purple, red and yellow in the autumn, which make the tree a favourite for ornamental planting
- the species is generally considered to be deciduous although occasionally, particularly in the southern part of its range, it may be semi-evergreen with little leaf fall
- the prickly fruits are round in shape and often stay on the tree for some time
- the tree has grey-brown fissured bark and stout brown twigs, often with cork-like wings
General: Sweetgum is a deciduous tree that is a member of the Hamamelidaceae, or witch-hazel family. It is named after the sweet balsamic sap which, when exposed, hardens into a fragrant gum. The trees can reach 30 to 40 meters in height and spread from 15 to 20 meters. The mature bark is rough, deeply furrowed and grayish brown. Young twigs are rusty red and frequently develop wings of corky bark. The star-shaped leaves, somewhat resemble maple leaves, except that they are arranged alternately instead of opposite. The leaves are 18 cm wide with long, thin petioles (6-15mm). Actively growing leaves are fragrant when crushed. They are palmate in shape with five to seven lobes and saw-toothed margins. Glossy-green in summer, the leaves turn bright yellow to deep red in the fall. The undersides of the leaves are pale green with a coating of fine white hairs. The small, greenish inconspicuous flowers have no true petals. The woody, ball-shaped, pendulous, burr-like fruits (3-4 cm) contain numerous, small seeds (1 cm) that are winged at one end. The seeds are contained in beak-like capsules to protrude from the surface (1 to 2 per capsule).
Distribution: Sweetgum is common in the Coastal Plain and Piedmont sections of the Southeastern United States. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.
Habitat: Sweetgum trees occur in moist or wet woods, tidal swamps, along streambanks, in clearings and old fields, and in low swampy bottomlands where they often form pure stands.
Sweet gum, American sweet gum, red gum, bilsted, star-leaved gum, alligator-tree
Range and Habitat in Illinois
Regularity: Regularly occurring
Florida and eastern Texas. It is found as far west as Missouri,
Arkansas, and Oklahoma and as far north as southern Illinois. It also
grows in scattered locations in northeastern and central Mexico,
Guatemala, Belize, El Salvador, Honduras, and Nicaragua [14,24,42]. It
is cultivated in Hawaii .
Occurrence in North America
MD MS NJ OH OK PA SC TN TX VA
-The native range of sweetgum.
Sweetgum is a large, native, long-lived, deciduous tree that reaches
heights of 50 to 150 feet (15-45 m) at maturity [6,14]. It is easily
recognizable by the long-petioled, star-shaped leaves which have five
long-pointed, saw-toothed lobes. The brown bark is deeply furrowed into
narrow scaley plates or ridges. Young sweetgum trees have long conical
crowns, while mature trees have crowns that are round and spreading.
Sweetgum is monoecious with the male flowers in several clusters and the
female flowers hanging at the end of the same stalk. The ball-shaped
fruits contain many individual seed-bearing sections, and persist
throughout the winter [16,18].
Habitat and Ecology
Range and Habitat in Illinois
Sweetgum is very tolerant of different soils and sites but grows best on
the rich, moist, alluvial clay and loamy soils of river bottoms .
Throughout the Piedmont Plateau, sweetgum shows good growth on river and
stream bottoms and shows considerable potential on many upland sites
Common tree associates of sweetgum include spruce pine (Pinus glabra),
Virginia pine (P. virginiana), red maple (Acer rubrum), box elder (A.
negundo), pignut, shellbark, shagbark, and mockernut hickories (Carya
glabra, C. laciniosa, C. ovata, C. tomentosa), and sugarberry (Celtis
laevigata). Common understory associates include dogwood (Cornus spp.),
alder (Alnus spp.), and eastern redbud (Cercis canadensis) [1,10,24].
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
More info for the terms: hardwood, swamp
44 Chestnut oak
51 White pine - chestnut oak
52 White oak - black oak - northern red oak
61 River birch - sycamore
62 Silver maple - American elm
64 Sassafras - persimmon
65 Pin oak - sweetgum
70 Longleaf pine
74 Cabbage palmetto
75 Shortleaf pine
76 Shortleaf pine - oak
78 Virginia pine - oak
79 Virginia pine
80 Loblolly pine - shortleaf pine
81 Loblolly pine
82 Loblolly pine - hardwood
83 Longleaf pine - slash pine
84 Slash pine
87 Sweetgum - yellow-poplar
88 Willow oak - water oak - diamondleaf oak
89 Live oak
91 Swamp chestnut - oak - cherrybark oak
92 Sweetgum - willow oak
93 Sugarberry - American elm - green ash
94 Sycamore - sweetgum - American elm
96 Overcup oak - water hickory
98 Pond pine
102 Baldcypress - tupelo
103 Water tupelo - swamp tupelo
104 Sweetbay - swamp tupelo - redbay
110 Black oak
This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):
FRES12 Longleaf - slash pine
FRES13 Loblolly - shortleaf pine
FRES14 Oak - pine
FRES15 Oak - hickory
FRES16 Oak - gum - cypress
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K097 Southeastern spruce - fir forest
K100 Oak - hickory forest
K102 Beech - maple forest
K103 Mixed mesophytic forest
K104 Appalachian oak forest
Soils and Topography
Throughout the Piedmont Plateau, sweetgum makes good growth on the river and stream bottoms and shows considerable potential on many upland sites. In the Carolina and Georgia Piedmont, for example, it is exceptionally competitive with other tree species on a wide range of soils with a site index for loblolly pine of 75 (at age 50) or greater.
In Maryland, sweetgum rarely makes acceptable growth on clay or gravelly clay upland soils and is rarely found on well-drained, sandy soils. Best growth rates are obtained on alluvial swamp sites and on imperfectly and poorly drained soils having a high clay content.
In the lower Mississippi Valley, site quality for sweetgum increases with the amount of exchangeable potassium in the soil and decreases as clay percentage increases. The best sites are those with medium-textured soils without a hardpan in the top 61 cm (24 in) and with moderate to good internal drainage. In the Mississippi Delta, sweetgum is most common on silty clay or silty clay loam ridges and silty clay flats in the first bottoms, which are very moist, but not too poorly drained. Along the eastern border of the Mississippi River, sweetgum is occasionally dominant on the loessial soils of the alluvial flood plain. It is characteristically dominant on the relatively impervious Alfisols of the Illinoian till plain, including the very poorly drained Avonburg, Blanchester, and Clermont silt loams (16).
Sweetgum is a hardy, ornamental tree that is valued for its shade as well as its lumber. They make attractive specimen trees all year and especially in the fall when the leaves turn brilliant colors before dropping in the fall. Young trees transplant best in the spring into well-watered soils. The roots are slow to develop. The trees may be planted in sun or part shade in soils that are medium to well drained and of medium to high fertility. The trees need medium to high moisture availability and are not suitable for dry areas. New trees volunteer readily from the seeds, however they generally do not germinate until the second year. The seeds are ripe when the fruit begins to lose its green color. Spread the fruits out to dry. When dry, they will open and release the seeds. Germination can be considerably increased if the seeds are prechilled for 15 to 90 days.
Associated Forest Cover
Among the most common associated tree species are red maple (Acer rubrum), boxelder (A. negundo), river birch (Betula nigra), pignut, shellbark, shagbark, and mockernut hickories (Carya glabra, C. laciniosa, C. ovata, C. tomentosa), sugarberry (Celtis laevigata), shortleaf pine (Pinus echinata), and loblolly pine (P. taeda). Several species of dogwood (Cornus) and alder (Alnus), as well as eastern redbud (Cercis canadensis), commonly occur as understory species with sweetgum.
Diseases and Parasites
Fire may be one of the major agents of damage to this species. Summer fires damage young sweetgum more than winter fires. Fire scars on living trees furnish entrance points for both insects and diseases. As long as the sapwood is not killed by fire, basal wounds are often covered with a gum exudation that protects them. With repeated fires, however, a tree is apt to have some sapwood killed, and fungi and insects may become established. In the lower delta of the Mississippi River, 42 percent of the sweetgum trees burned once showed decay 8 years later; 79 percent of the trees burned repeatedly during an 8-year period showed decay (16).
The four most common decay organisms reported in the Mississippi River Delta were Fomes geotropus, Pleurotus ostreatus, Lentinus trigrinus, and Ganoderma lucidum (16).
Other diseases of sweetgum that may be important occasionally are an abiotic leader dieback or blight, twig canker, and trunk lesion caused by Botryosphaeria ribis, and bleeding necrosis, which may be a combination of sweetgum blight and B. ribis trunk lesion (8). Of these, only sweetgum blight is widely distributed and has caused heavy mortality in several States. It has received intensive study in Maryland and Mississippi. Drought appears to be the primary cause. In the lower Mississippi River flood plain, blight severity was found to be correlated with soil properties affecting moisture supply. Severity of dieback was reduced by 68 percent in 2 years by irrigating when soil moisture dropped below 40 percent of field capacity (16). There is a good possibility that sweetgum blight is most common in stands of root sprout origin. In the Georgia Piedmont and Coastal Plain of South Carolina, many groups of trees are composed of stems that are of root sprout origin and depend on a single root system complex for water uptake. During prolonged droughts such as occurred in the 1950's, this limited root system may not be adequate to satisfy the water requirements of the sprout complex, and many of the stressed trees may suffer blight.
Except for leaffeeders, insects usually attack only trees that are already damaged, decadent, or dead. These include the bark beetles (Dryocoetes betulae and Pityophthorus liquidambarus), the ambrosia beetles, which include Platypus compositus, and the darkling beetles (Strongylium spp.). The leaffeeders include the forest tent caterpillar (Malacosoma disstria) and the luna moth (Actias luna) (1). In addition, a treehopper (Strictocephala militaris) is known to spend its entire life cycle on sweetgum in northeast Georgia but is not considered to be harmful (5).
Plant Response to Fire
Repeated annual summer burns, however, will eventually deplete
carbohydrate reserves and kill the plant [41,48].
Broad-scale Impacts of Fire
Fire scars on living trees provide entry points for insects and
diseases. As long as the sapwood is not killed by fire, basal wounds
are often covered with a gum exudation that protects them. After
repeated fires, however, a tree is apt to have some sapwood killed and
fungi and insects may become established [24,47].
Immediate Effect of Fire
Fire typically top-kills sweetgum. Hot summer fires may deplete
carbohydrate reserves and eventually kill the tree [41,48].
survivor species; on-site surviving root crown or caudex
off-site colonizer; seed carried by wind; postfire years 1 and 2
Fire is one of the major agents of damage to sweetgum. Its relatively
thin bark make it highly susceptible to fire . Following top-kill
by fire, sweetgum sprouts from the stump or root crown [41,48].
More info for the terms: natural, tree
Sweetgum is classified as shade intolerant . In pure stands on
bottomland sites, young sweetgum is able to endure some shade and
crowding. With increase in age the tree becomes less tolerant of
competition. Following natural decrease in the canopy, enough sunlight
reaches the ground to permit an understory stand to develop [12,24].
Although sweetgum is an early invader, it seldom becomes a dominant
Seed production and dissemination: Sweetgum produces an abundance of
lightweight seed. The tree begins to produce seed when 20 to 30 years
old, and crops remain abundant for 150 years. Fair seed crops are
produced each year, with bumper crops every 2 to 3 years [2,24]. Under
conditions of full sunlight and rich moist soil, each fruit may average
as many as 50 sound seeds. Seed is primarily dispersed by wind; the
maximum dispersal distance recorded was 600 feet (183 m) but
ordinarily 96 percent of the seed fall within 200 feet (61 m) of the
point of release [24,38].
Seedling development: Sod is not a serious hindrance to seed
germination; however, when additional sweetgum production is desired in
partially cutover stands, exposed mineral soil and abundant direct
sunlight are necessary [4,22]. Root development varies with the growing
site. A deep taproot and numerous horizontal rootlets usually develop
early, but in wet areas the root system is shallow and wide spreading,
with little or no taproot [25,39]. On an abandoned field adjacent to a
swamp in Maryland, 5-year-old seedlings averaged 8.7 feet (2.6 m) in
height . On favorable sites in the lower Mississippi Valley,
seedlings grow as much as 2 feet (0.6 m) during the first year [24,49].
Vegetative reproduction: Sweetgum is capable of sprouting until it is
approximately 50 years old. Although sweetgum seedlings reach a height
of 4.5 feet (1.4 m) in 3 to 5 years, sprouts often reach this height in
one growing season. Ten-year old sprouts frequently have the same size
and appearance as 18- to 20-year-old seedlings in the same stand
Growth Form (according to Raunkiær Life-form classification)
Fire Management Considerations
sweetgum. In the Coastal Plain of South Carolina, five consecutive
summer fires killed 85 percent or more of the root stalks of sweetgum.
Winter fires did not kill appreciable numbers of root stalks but did
top-kill most sweetgum 2 inches (5 cm) or less d.b.h. .
Reaction to Competition
Life History and Behavior
Sweetgum flowers appear from March to May, depending on latitude and
weather. The fruit ripens from September to November; the fruit often
persists through the entire winter [6,24].
The importance of root sprout formation with sweetgum regeneration is evident from observations made in natural stands of mixed pines and hardwoods in the Georgia Piedmont that have been logged for sawtimber. In most of the stands examined, advance reproduction of sweetgum was clearly evident, accounting for 10 to 60 percent of all hardwood production. The invasion of such stands by young sweetgum has usually been attributed to natural seeding, but most of the young, vigorously growing stems observed in the Georgia Piedmont were of sprout origin. It is not uncommon to find as many as 40 or more stems from seedling to sapling size on the root systems of a single parent tree. Additional work with root sprouts in the Coastal Plain of South Carolina showed that sprout height after 8 years was directly correlated with the diameter of the lateral root from which the sprout originated; the larger the root the taller the sprout.
The persistence of root sprouts was revealed when soil was removed from several 0.04-ha (0.1-acre) plots on a Georgia Piedmont bottom-land site that supported pure stands of sweetgum. Trees ranged in d.b.h. from about 25 to 41 cm (10 to 16 in) and varied from dominant to intermediate in the crown canopy. More than 70 percent of the trees were of sprout origin on most plots. Other stands that were primarily of seed origin were later found on abandoned agricultural lands. These observations indicate that a significant portion of sweetgum regeneration following logging can be expected to originate from root sprouts. The long-term development and management of these stands have yet to be clarified.
Plantation establishment of sweetgum is becoming increasingly important throughout the southern region, and it is rapidly becoming the hardwood species most commonly established. Results of early plantation establishment and development have been quite variable. This variability in growth has been attributed to seedling quality. Seedlings with a large root-collar diameter achieve the best growth, and planting seedlings with a root-collar diameter of less than 6 mm (0.25 in) is not recommended (2). In a Georgia Piedmont bottom-land site, seedlings at age 7 ranged in height from 3.8 to 6.2 in (12.4 to 20.2 ft). After 7 years on a strip mine in Indiana, sweetgum averaged 2.1 in (7 ft). On favorable sites in the lower Mississippi Valley, seedling height growth of 0.6 m/yr (2 ft/yr) has been reported. On upland sites, 5-year height growth varies considerably, from 1.1 in (3.6 ft) on an eroded field to 2.0 in (6.5 ft) on areas reverting to woody cover. It is this slow, early growth of sweetgum plantations that is of concern to silviculturists because it necessitates expensive cultivation to reduce weed competition and thereby maintain acceptable survival until height growth begins. First-order lateral root morphology of nursery-lifted sweetgum seedlings reflects their future competitiveness in the field. Early growth and survival can be acceptable, even in moderate to severe drought years, if nursery-lifted seedlings have five or more first-order lateral roots exceeding 1 mm (0.04 in) in diameter at the junction with the taproot. As many as one third of all seedlings in selected families growing in one nursery did not meet these standards making them poorly competitive in a forest environment (10).
Recent work suggests that vesicular-arbuscular mycorrhizae can significantly improve seedling quality from nurseries (9,13,14) and alter this pattern of low growth so commonly encountered during the first 3- to 5-year period following plantation establishment. On an upland Piedmont site in South Carolina, for example, total heights on sweetgum plots after three growing seasons have been observed to exceed the 2.0 in (6.5 ft) reported after five growing seasons from areas just reverting to woody cover. On a denuded borrow pit in the South Carolina Piedmont, soil amended with as little as 13 mm (0.5 in) of sewage sludge evenly distributed and disked into the soil resulted in fourth-year height of 2.8 in (9.2 ft) for sweetgum (3). The seedlings used in this experiment were heavily mycorrhizal with a vesicular-arbuscular fungus (Glomus mosseae) at outplanting.
Seed Production and Dissemination
There are approximately 365 g (0.8 lb) of clean seeds per 35 liters (1 bushel) of balls, and the number of seeds per 454 g (1 lb) varies from 65,000 to 98,400, with an average of 82,000 (17). Seed soundness may reach 80 to 90 percent in a good seed year but may drop to 10 to 20 percent in a bad seed year. There are no data relating to the number of sound seed required for normal seed-ball development. The maximum distance of seed dispersal recorded is 183 m (600 ft), but ordinarily 96 percent of the seed falls within 61 m (200 ft) of the point of release (16).
Flowering and Fruiting
Growth and Yield
The excurrent growth habit is maintained longer on the more moist, fertile bottom-land sites than on the drier, less fertile upland sites. However, on excessively dry sites the excurrent growth habit is characteristically maintained for many years and may represent a morphological growth response mediated by moisture availability.
The average 10-year diameter growth for overmature sweetgum in the southern region was reported to be 4.8 cm (1.9 in), and for immature trees of medium to high vigor, 8.9 cm (3.5 in) (16). In the Mississippi Delta, pure stands of sweetgum average 84 to 112 m³ /ha (6,000 to 8,000 fbm/acre). Very good stands have 210 to 280 m³/ha (15,000 to 20,000 fbm/acre) with up to 420 to 560 m³ /ha (30,000 to 40,000 fbm/acre) on small, selected areas. On ridges and upland sites, stands are usually less dense than on bottom-land sites.
Molecular Biology and Genetics
Barcode data: Liquidambar macrophylla
Statistics of barcoding coverage: Liquidambar macrophylla
Public Records: 1
Specimens with Barcodes: 1
Species With Barcodes: 1
Barcode data: Liquidambar styraciflua
Statistics of barcoding coverage: Liquidambar styraciflua
Public Records: 10
Specimens with Barcodes: 10
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
- Needs updating
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Reasons: Range extending from Connecticut southward and westward to Texas, reappearing on the mountains of central and southern Mexico and the highlands of Guatemala, Honduras and Nicaragua.
Please consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status (e.g. threatened or endangered species, state noxious status, and wetland indicator values).
most serious competitors of pine seedlings in southeastern forests.
Silvicultural practices have called for the control of sweetgum in areas
where it competes heavily with pine seedlings . Basal applications
of Garlon 4 top-killed 81 percent of 2 inch (5 cm) d.b.h or smaller
Cultivars, improved and selected materials (and area of origin)
These plant materials are readily available from commercial sources. Contact your local Natural Resources Conservation Service (formerly Soil Conservation Service) office for more information. Look in the phone book under ”United States Government.” The Natural Resources Conservation Service will be listed under the subheading “Department of Agriculture.”
The trees are relatively trouble-free and generally do not require pruning. The fruits can look somewhat messy in fall and winter when they drop, especially onto a manicured lawn where they can also make mowing difficult. Avoid planting near a patio or sidewalk where the fruits can be painful when stepped on with bare feet.
Relevance to Humans and Ecosystems
Uses: MEDICINE/DRUG, Folk medicine, Building materials/timber
Comments: A resin or balsam, excreted from wounds in the bark, is collected in considerable quantities in Mexico and Central America and has been much used for medicinal purposes from the earliest times. In the U.S. used for construction, furniture, veneers, etc.
Value for rehabilitation of disturbed sites
Sweetgum stem cuttings have been successfully planted for streambank
protection and reclamation of sites disturbed by coal strip mining
Sweetgum growth and survival was good when planted on favorable sites
but decreased when seedlings were planted concurrently with ground cover
or in previously established cover of grasses and legumes on mined sites
in southeastern Indiana [3,8].
Wood Products Value
Sweetgum is primarily used for lumber, veneer, and plywood. The lumber
is used to make boxes, crates, furniture, interior trim, and millwork.
The veneer is used primarily for crates, baskets, and interior woodwork.
Sweetgum is also used for crossties and fuel, and small amounts go into
fencing, excelsior, and pulpwood [37,42].
Other uses and values
is used extensively in Mexico and Europe as a substitute for storax.
Various ointments and syrups are prepared from the resinous gum and are
used in the treatment of dysentery and diarrhea. The gum is sometimes
chewed by children, and it is also used as a perfuming agent in soap
The beautiful red and yellow color variations of sweetgum's autumn
foliage make it highly prized as an ornamental [33,45].
Importance to Livestock and Wildlife
National Forest of Georgia, sweetgum was lightly to moderately browsed
by white-tailed deer during the fall and winter . The seeds are
eaten by birds, squirrels, and chipmunks .
nutrient values for sweetgum on unburned plots on the Siecke
State Forest, Texas, varied seasonally as follows :
protein fat fiber extract ash phosphorus calcium
Spring 10.76 2.78 9.08 58.49 3.84 6.13 0.63
Summer 7.00 2.78 12.09 59.39 3.73 0.07 0.86
Fall 5.74 3.09 11.08 59.72 5.33 0.06 1.28
Winter 4.42 2.51 20.23 54.64 3.21 0.06 1.70
Ethnobotanic: The sweetgum tree was used by the Cherokee, Choctaw, Koasati, Rappahannock and other Native American tribes for various purposes. The hardened gum, or rosin from the tree was used as chewing gum. A piece of the bark was knocked from the tree. After one week, the sap from the wound was hardened and could be collected and used for chewing gum. Tea was made from both the fruits and the bark. The hardened sap was rolled up and then placed in a dog’s nose to treat distemper. A salve was made by mixing the plant with animal tallow for application to wounds, cuts, sores, bruises, and ulcers. The plant was boiled until a scum rose to the top. This scum was then mixed with the roots of Obolaria virginica and used as a dressing for cuts and bruises. The roots were boiled into a strong tea to treat skin sores that were possibly caused by small worms under the skin. A “drawing plaster” was made from the gum. Ten to a dozen drops of the sap were taken before meals to reduce fevers. The sap and inner bark were used to treat diarrhea and dysentery. The bark was used to make an infusion that was used as a sedative for nervous patients and for patients who were well in the day but sick during the night. The plant was used to treat colic, internal diseases and to “comfort the heart.”
Wildlife: Goldfinches, purplefinches, mallard ducks, bobwhite quails, Carolina chickadees, yellow-bellied sapsuckers, white-throated sparrows, towhees, Carolina wrens, squirrels, and chipmunks eat the seeds of sweetgum trees. Beavers use the wood for constructing dams.
Other: Liquidambars are valued for their timber and for the aromatic sap, called styrax. The timber provides pulp, veneer and lumber. The wood is used in cabinetry, home interiors, boxes and utensils. The balsamic sap is used as an ingredient in both medicine and perfume.
Liquidambar styraciflua, commonly called American sweetgum, sweetgum, sweet gum, sweet-gum (sweet gum in the UK), hazel pine, American-storax, bilsted, red-gum, satin-walnut, star-leaved gum, or alligator-wood 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. Sweet gum is one of the main valuable forest trees in the southeastern United States, and is 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.
This plant's genus name Liquidambar was first given by Linnaeus in 1753 from [the Latin] liquidus, fluid, and the Arabic ambar, amber, in allusion to the fragrant terebinthine juice or gum which exudes from the tree. Its specific epithet styraciflua is an old generic name meaning flowing with styrax (a plant resin). 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", 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.
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.
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.
Sweetgum is one of the most common hardwoods in the southeastern 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.
The US government distribution maps for this species are incorrect concerning the southern limit of distribution in Florida. This species occurs abundantly at Highlands Hammock State Park, Sebring, Highlands County, FL, and even southwest of Lake Okeechobee. (see the Univ. South Florida Atlas of Florida Plants)
Liquidambar styraciflua is a medium-sized to large tree, growing anywhere from 33–50 feet (10–15 m) in cultivation and up to 150 feet (46 m) in the wild, with a trunk up 2–3 feet (0.61–0.91 m) in diameter, on average. Trees may live to 400 years. The tree is a symmetrical shape and crowns into an egg shape when the branches get too heavy after its first two years of cultivation.
Bark and branches
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. The bark is a light brown tinged with red and sometimes gray with dark streaks and weighs 37 lbs. per cubic foot. It is deeply fissured with scaly ridges. The branches carry layers of cork. The branchlets are pithy, many-angled, winged, and at first covered with rusty hairs, finally becoming red brown, gray or dark brown. As an ornamental tree, the species has a drawback—the branches may have ridges or "wings" that cause more surface area, increasing weight of snow and ice accumulation on the tree. However, the wood is heavy and hard with an interlocking grain, but is difficult to season.
They are long and broad, with a 6–10 cm petiole. The rich dark green, smooth, shiny, star-shaped 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). 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 leaves are three to seven inches broad 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. They contain tannin and when bruised give a resinous fragrance.
While the starry five-pointed leaves of Liquidambar resemble those of some maples (Acer), Liquidambar is easily distinguished from Acer by its glossy, leathery leaves that are positioned singly (alternate), not in pairs (opposite) on the stems. Luna and Promethea moth caterpillars feed on the leaves.
The flowers typically appear in March to May and persist into Autumn, sometimes persisting into the Winter. They are typically about 1–1.5 inches in diameter and are covered with rusty hairs. The flowers are unisexual and greenish in color. Staminate flowers in terminal racemes two to three inches long, 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 are 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. There are many ovules but few mature.
The distinctive compound fruit is hard, dry, and globose, 1–1.5 inches 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 "burr (or bir) balls", "gum balls", "space bugs", "monkey balls", "bommyknockers" or "sticker balls".
The fruit is a multicapsular spherical head and hangs on the branches during the winter. The woody capsules are mostly filled with abortive seeds resembling sawdust. The seeds are about one-quarter of an inch thick, winged, and wind-dispersed. Goldfinches, purple finches, squirrels, and chipmunks eat the seeds of the tree. The seeds stratify within 30–90 days at 33°–41 °F or soaked in water for 15–20 days. 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. The long-persisting fallen spiked fruits can be unpleasant to walk on; sweet gum is banned in some places for this reason. In abundance, they can leave a lawn lumpy. The winter buds are 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.
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) and may have black grain in the heartwood; it is 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. It is too liable to decay for outdoor use.
In the carpentry industry, the timber is referred to as satin walnut and is one of the most important materials for plywood manufacturers. It is used for furniture, interior trim, railroad ties, cigar boxes, crates, flooring, barrels, woodenware, and wood pulp. It is also used for 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, 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.
The tree's gum resin, for which the tree is named, exudes from the bark of the tree when wounded. It has many names, including liquid amber or copalm balsam. It 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. 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, and good against such conditions as sciatica and weakness of the nerves. The Aztecs believed styrax to have medicinal properties; mixed with tobacco, the gum was once used for smoking at the court of the Mexican emperors. Styrax is still used to make chewing gum and also as an ingredient for the tobacco and perfume industry, including the making of perfumes and cosmetics. The styrax gum is also used medicinally to treat coughs, wounds, and dysentery. In fact, the old-fashion Friar's basalm contains liquid styrax and is used as an inhalant in bronchial upsets.
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. Industrially produced styrene is now used to produce polystyrene plastics, including Styrofoam.
Liquidambar styraciflua is a popular ornamental and forestal tree, cultivated for its distinctive foliage and intense autumn colors. It is commonly grown throughout its native North American range as well as many other temperate parts of the world. The species grows best in moist, acidic loam or clay soil, and tolerates poor drainage. It typically grows with other coastal plain species such as willow oak and sweetbay magnolia. Its salt tolerance is moderate. Chlorosis can develop on alkaline soil, especially where organic matter is low. Also, the American sweetgum tree doesn't grow well in shady areas.
- Burgundy – dark red to purple fall colors may persist through winter
- Clydesform – columnar or narrowly pyramidal; slow growth to 9 meters; yellow-orange fall colors; also sold as 'Emerald Sentinel'
- Festival – columnar; pale green summer leaves; bright fall hues of yellow, pink and red; less hardy than most
- Goduzam – variegated; pink to red-purple in fall; also called 'Gold Dust'
- Grazam – pyramidal, with glossy leaves. Orange, red and purple fall colors
- Gumball – dwarf shrubby cultivar seldom more than 6 feet (2 meters) tall, with purple-red fall color
- Lane Roberts (agm)
- 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, originally discovered in North Carolina in the 1930s
- Slender Silhouette – very narrow columnar form
- Worplesdon (agm) – cutleaf cultivar with orange, red and purple fall colors
The organizers of the September 11th Memorial in New York donated a grove of sweet gum trees to the Flight 93 Memorial in Shanksville, Pennsylvania.
Infection on Liquidambar styraciflua
The imperfect fungus Tubakia dryina Sutton is a leaf parasite reported to occur on a wide range of host plants, including species of Sweet Gum (Liquidambar styraciflua L.). Limber and Cash reported that leaf spots produced by this pathogen on several different genera of forest trees were 2–5 mm diameter with regular margins. During the summer of 1994 in the Nacogdoches County area of Texas, a prominent leaf spot on Sweet Gum was widespread. Infected leaves had numerous necrotic lesions, each surrounded by a reddish halo. The lesions tended to merge resulting in large areas of dead tissue. Infection and fungal development of T. dryina were investigated on leaves of sweet gum using a combination of microscopic techniques. T. dryina infection on Sweet Gum has been associated with the disease red leaf spot. Results of this investigation indicate that T. dryina can penetrate leaf tissue directly, thus having the ability to initiate infection on both upper and lower leaf surfaces. In other regions of the U.S., Sweet Gum populations may not be as susceptible to local populations of this fungus. Environmental stress factors may also be involved, as reports have indicated that herbicide application and chlorosis caused by iron deficiency may increase susceptibility of T. dryina. Tannins (a type of biomolecule found in trees to protect it from fire, insects, and bacteria) have been reported to occur in healthy tissue of a variety of plants including sweet gum. They may prevent pathogen invasion by inhibiting fungal enzyme activity. Although cells of healthy sweet gum tissue appear rich in tannins, these materials apparently were not effective in preventing fungal colonization by T. dryina.
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- Schwartz, Ed. "Victors and Vanquished" p. 143 Cortez and his captains smoke liquidambar mixed with tobacco with Montezuma after they feast
- Liquidambar styraciﬂua: a renewable source of shikimic acid. Liza B. Enrich, Margaret L. Scheuermann, Ashley Mohadjer, Kathryn R. Matthias, Chrystal F. Eller, M. Scott Newman, Michael Fujinaka and Thomas Poon, Tetrahedron Letters, 2008, volume 49, pages 2503–2505, doi:10.1016/j.tetlet.2008.02.140
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This article incorporates text from a publication now in the public domain: Chambers, Ephraim, ed. (1728). "article name needed". Cyclopædia, or an Universal Dictionary of Arts and Sciences (first ed.). James and John Knapton, et al.
|Wikimedia Commons has media related to Liquidambar styraciflua.|
- USDA Plants Profile: Liquidambar styraciflua
- Flora of North America: Liquidambar styraciflua
- Interactive Distribution Map for Liquidambar styraciflua
- University of Michigan - Dearborn: Native American Ethnobotany of Liquidambar styraciflua
- USFS Silvic Manual: Liquidambar styraciflua
- USGS Species Distribution Maps: Liquidambar styraciflua (pdf file).
- Bioimages.vanderbilt.edu: Liquidambar styraciflua images
- Landscaping.about.com: 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.
Liquidambar styraciflua was well known as a medicinal plant by Native Americans. Cherokee, Choctaw, Houma, Koasati, and Rappahannock tribes used it in various ways, especially the gum, bark, and root, as an antidiarrheal, dermatological aid, gynecological aid, sedative, febrifuge, and for related uses (D. E. Moerman 1986).
Liquidambar styraciflua produces a balsamic oleo-resin called American styrax or storax, a thick, clear, brownish yellow, semisolid or solid with a pronounced aromatic odor. It is chewed as a sweet, natural gum. The balsam is collected from the inner bark of the tree after wounding or deliberate gashing. It is used in soaps and cosmetics, as a fixative in perfumes, adhesives, lacquers, and incense, and as a flavoring in tobacco. The wood is used for cabinet making, furniture, veneer, interior finish, barrels, and wooden dishes. Medicinally the gum has been used for catarrh, coughs, dysentery, sores, and wounds of both humans and domestic animals.
The largest known tree of Liquidambar styraciflua , 41.4 m in height with a trunk diameter of 2.25 m, is recorded from Craven County, North Carolina (American Forestry Association 1994).
Names and Taxonomy
styraciflua L. . Two forms of sweetgum are recognized in
horticulture. The round-lobed American sweetgum, L. styraciflua forma
rotundiloba Rehd., has three to five short, rounded lobes on the leaves.
Weeping American sweetgum, L. styraciflua forma pendula Rehd., has
pendulous branches forming an almost columnar head [44,45]. There are no
recognized subspecies or varieties.