sweet gum

Sweetgum
Sweetgum buds in New Orleans during spring
Scientific classification
Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Saxifragales
Family:	Altingiaceae
Genus:	Liquidambar L.
Species
See text

Sweetgum (Liquidambar) is a genus of four species of flowering plants in the family Altingiaceae, though formerly often treated in the Hamamelidaceae. They are all large, deciduous trees, 25-40 m tall, with palmately lobed leaves arranged spirally on the stems. The leaves turn multiple colors in the fall. The flowers are small, produced in a dense globular inflorescence 1-2 cm diameter, pendulous on a 3-7 cm stem. The fruit is a woody multiple capsule 2-4 cm diameter (popularly called a "gumball"), containing numerous seeds. In more northerly climates, sweetgum is among the last of trees to leaf out in the spring, and also among the last of trees to drop its leaves in the fall.

Species

• Liquidambar acalycina - Chang's Sweetgum (central & southern China)
• Liquidambar formosana - Chinese Sweetgum or Formosan Sweetgum (central & southern China, southern Korea, Taiwan, Laos, northern Vietnam).
• Liquidambar orientalis - Oriental Sweetgum or Turkish Sweetgum (southwest Turkey, Greece: Rhodes).
• Liquidambar styraciflua - American Sweetgum (eastern North America from New York to Texas and also eastern Mexico to Guatemala).

The genus was much more widespread in the Tertiary, but has disappeared from Europe due to extensive glaciation in the north and the Alps, which has served as a blockade against southward migration. It has also disappeared from western North America due to climate change, and also from the unglaciated (but nowadays too cold) Russian Far East. There are several fossil species of Liquidambar, showing its relict status today.

Uses

The wood is used for furniture, interior finish, paper pulp, veneers and baskets of all kinds. The heartwood once was used in furniture, sometimes as imitation mahogany or circassian walnut. It is used widely today in flake and strand boards. Sweetgum is a foodplant for various Lepidoptera caterpillars, such as the gypsy moth. The American Sweetgum is widely planted as an ornamental, not only within its natural range.

Bark "Gray to grayish brow, deeple furrowed with long, somewhat flattened scaly ridges, corky.

Leaves Alternate, simple, blades 8-15 cm long about as wide; orbicular, star-shaped, deeply and palmately 5-7-lobed; apex of lobes acuminate; margin finely serrate; leathery; glabrous, bright green and lustrous above, paler beneathe with axillary tufts in the axils of primary veins, turning yellow, orange, dark red, or purple in autumn; reisnous odor when crushed; petioles long, 6-10 cm.

'Twigs Slender to stout, green becoming yellowish or redish brown, lustrous, often developing corky ridges or thick wings, aromatic; pith continuous, angled or star-shaped" (Michigan Trees, Barnes, Wagner, 2008).

Wood: "Hard, strong, even-grained, reddish brown. Uses include flooring, plywood, furniture, veneer, interior woodwork, railroad ties, construction lumber, paper products" (Michigan Trees, Barnes, Wagner, 2008).

Flowers "April-May, with the leaves; small, in globose heads; perianth 0; staminate flw. in small heads forming a terminal raceme; pistillate fls. in small heads with two neaked ovaries subtended by small scaled. Trees monoecious. Wind-Pollinated.

Fruit Aggregate of capsules, woody, globose, dark brown, about 4cm across and situated on a long peduncle, persistent in winter; 2 winged seeds per capsule.

Distribution Wide-spread in the mid-Atlantic, mid-South, and Southeastern United States. Planted widely outside its range, including in southern Michigan.

Habitiat Widely adaptable to diverse site conditions. Characteristic of alluvial flood-plains of large rivers and moist bottomland sites of small rivers and creeks. Also typically found on many upland sites. Tolerates flooding during the growing season and clayey, poorly drained soils. Occurs in many forest cover types; major associates include red maple, boxelder, river birch, shagbark hickory, redbud, and loblolly pine" (Michigan Trees, Barnes, Wagner, 2008).

References and external links

• Hsu, E. & Andews, S. (2005). Tree of the year: Liquidambar. International Dendrology Society Yearbook 2004: 11-45.
• Deterministic Plio-Pleistocene extinctions in the European cool-temperate tree flora. Ecology Letters 6 (7): 646-653. July 2003.
• Possible link between sweetgum fruit and fighting avian flu Highlights of American Chemical Society meeting in Atlanta, American Chemical Society, March 2006.
• Trees of Western North Carolina - Sweetgum

Sweetgum seed pods in Michigan during winter.

Wikimedia Commons has media related to: Liquidambar