Identifying characteristics:
The sweetgum is a straight-trunked, symmetrical tree growing to 80 feet
tall. It has a conical crown when young, becoming more rounded at maturity.
The leaves are simple, alternate,
finely toothed and star-shaped (palmately 5- to 7-lobed). They are leathery,
glossy and dark green above; paler beneath and hairy at the principal vein
axils. Petioles are almost as long as the leaf blade. The spectacular fall
coloring of yellow, red and purple is held late in the season. Small, green
flowers are produced with the leaves in spring in upright, terminal
racemes (male) and bell-shaped heads (female), on the same tree. Fruits (aggregates of capsules) are produced
in globular, woody, prickly balls dangling on long stems. The twigs
often develop corky ridges in their second year. The ovoid buds are
reddish-brown, with 6 or more scales. Bark
is grayish-brown and deeply furrowed with rounded, flaky ridges.
Similar species:
Ecology:
Distribution: The sweetgum is native to the eastern and southern
US, extending to Mexico. It is not dependably hardy in most of Iowa, and
will suffer twig dieback in severe winters.
Habitat: This is a bottomland species, preferring rich, moist alluvial soils, but is found growing on a variety of sites. It is a reasonably fast grower, invading floodplains and abandoned fields in the south. The sweetgum is particularly susceptible to bleeding necrosis, a fungus disease that causes the bark to bleed profusely. No control is available, and infected trees should be removed. Other problems include sweetgum webworm, sweetgum scale and walnut scale. In alkaline soils iron chlorosis may be a problem.
Uses:
Wood: This is one of the most important US broadleaf timber trees.
The wood is moderately hard and heavy, close-grained and straight.
It is used for furniture, veneer, cabinets, interior trim and for many other
purposes. The thick sapwood (called Sap Gum) is white and the heartwood
(called Red Gum) is pink or reddish, and they are sold as two distinct woods.
The name "sweetgum" originates from the sweet, gummy sap that
is used as the base of salves, soaps, adhesives and tobacco flavoring. In
the pharmaceutical trade the gum is called "copalm balm" or "liquidambar."
Early settlers used it to treat skin troubles, diphtheria, dysentery and
catarrh. The gum from a species native to Turkey, L. orientalis,
was prized as an incense in Christian and Indian temples.
Wildlife: This species is used to only a small extent by wildlife. Birds, especially finches, eat the seeds, as do squirrels and chipmunks. Beavers eat the wood.
Horticulture: Although the sweetgum is an excellent lawn tree, several drawbacks impact on its horticultural use. The spreading roots require space, the fleshy tap root makes it slow to re-establish after transplanting and it does not tolerate pollution. The prickly balls remain on the tree into winter, and can be messy-dropping from the tree over an extended period from December to April. 'Moraine' is the most cold-hardy cultivar, withstanding temperatures to minus 25 degrees F. It has brilliant red fall color and is a fast grower.
