This tree is 60-90' tall at maturity, forming a trunk about 2½-4'
across and a crown with spreading leafy branches. The crown of a young
tree is pyramidal, while the crown of an old tree is ovoid. Trunk bark
of mature trees is gray or gray-brown with irregular furrows and narrow
Branch bark is more gray and smooth, while twigs are yellowish brown to
brown, glabrous, and covered with scattered white lenticels.
Sometimes the twigs and smaller branches develop corky wings,
otherwise they are wingless; small twigs are often bumpy from petiole
scars. Young shoots are light green
and glabrous. Alternate star-shaped leaves about 3-6" long and
similarly across occur along the twigs and shoots; they have 5 palmate
lobes (or less often 7 lobes) that are triangular-shaped and their
margins are finely serrated. Sometimes, there are 1-2 small secondary
lobes on the lower lobes of a leaf. The base of leaf is truncate to
indented. For mature leaves, the upper surface is medium-dark
green and glabrous, while the lower surface is medium green and mostly
hairless, except for fine short hairs along the primary veins. In
addition to these hairs, sometimes the lower leaf surface is
sparsely covered with short appressed hairs between the veins. The
petioles are 2½-6" long, light green, and glabrous.
Sweet Gum is
monoecious, producing separate male (staminate) and female (pistillate)
flowers on the same tree. The male inflorescence consists of a raceme
of clustered male flowers about 1-2½" long; this raceme is greenish
yellow and ascending. Individual male flowers are about 1/8" (3 mm.)
consisting of 4-8 fertile stamens that originate from a short disc. The
of the raceme are hairy. The female inflorescence consists of a green
globoid head of female flowers about ¾" across; this floral head droops
downward from a stalk (peduncle) about 1-3" long; the stalk is light
green and glabrous. Individual female flowers are about 1/8" (3 mm.)
consisting of a 2-celled ovary with 2 spreading styles and 4-8 sterile
stamens (staminodes). The blooming
period occurs during mid- to late spring shortly after the emergence
of vernal leaves. The flowers are cross-pollinated by the wind.
During the summer, the female inflorescences become transformed into
spiky seed capsules about 1-1½" across, turning brown at maturity
during the autumn. Between each pair of hardened styles, each seed
capsule splits open to release 1-2 seeds. Usually, only a minority of
capsules in each head produce fertile seeds. These seeds are about 1/3"
(8 mm.) long, flattened, and winged; they are distributed by the wind.
empty heads of seed capsules often persist on the tree through the
winter. In dry areas, the root system consists of a well-devloped
taproot and lateral roots, while in soggy areas it consists of
lateral roots that are shallow and widely spreading. The deciduous
leaves can assume various colors during the autumn, including yellow,
orange, red, pink, or dark purple.
The preference is full
or partial sun, moist conditions, and fertile soil containing loam or
clay-loam. Alkaline soil can cause difficulty in absorbing iron and
other nutrients, therefore it should be avoided. Occasional flooding is
tolerated if it is relatively short in duration. Seedheads are produced
on trees about 25 years old and annually thereafter. The biggest
drawback in cultivating this tree is the abundance of spiky seedheads
that fall to the ground from autumn to spring. In addition to their
unsightly appearance, they are difficult to walk on and require
additional labor to remove.
Sweet Gum is occasional in southern Illinois, otherwise it is largely
absent from natural areas of the state (see Distribution
lies along the NW range-limit for this tree; it common in many areas of
southeastern United States. Habitats consist of depressions in upland
woodlands, bottomland woodlands, riverbanks, drier areas of
swamps, shaded gravelly seeps, and abandoned fields. Sweet Gum
requires occasional disturbance to create openings in wooded areas that
it can colonize. Otherwise, it is replaced by more shade-tolerant
trees. Sweet Gum is often cultivated as a landscape tree in yards and
Compared to other trees, very few insects
appear to feed
on Sweet Gum. The caterpillars of the moths Actias luna
(Large Paectes) feed on the leaves of this tree,
while larvae of the bark beetle Pityophthorus
damaged or dead trees. The seeds are a source of food to some songbirds
during the fall or winter: these species include the Mourning Dove,
Eastern Towhee, Carolina Chickadee, Eastern Goldfinch, Purple
Finch, Common Redpoll, Slate-Colored Junco, and White-Throated Sparrow.
In addition, the seeds are a minor source of food for the Gray Squirrel
and Eastern Chipmunk. When Sweet Gum occurs near bodies of water, the
Beaver occasionally uses its wood and branches for food and
The Arboretum of the University of Illinois and
along a sidewalk in a residential area of Urbana, Illinois.
This tree has distinctive star-shaped leaves, making it relatively easy
to identify. The wood is occasionally used to make veneer, furniture,
boxes and crates, rail ties, pulpwood, and other items, but it has a
tendency to shrink and warp. A fragrant gum is produced from the
sap of Sweet Gum that is referred to as 'American Storax.' It has been
used as a fixative for perfumes, to lend fragrance to ladies' apparel,
and other applications. The crushed leaves also exude a pleasant
fragrance. Some authorities assign this tree to the Witch Hazel
family (Hamamelidaceae), but recent genetic evidence suggests that it
not closely related to species in this family. Fossil evidence suggests
that trees in the Sweet Gum family were more common and widely
distributed in the past than they are at present.