American Sycamore - Lake Forest College

American Sycamore | Platanus Occidentalis
(other common names: American plane tree, buttonwood,
and button ball-tree)
It is a member of one of the planet's oldest clan of trees
(Platanaceae). Paleobotanists have dated the family to be over 100
million years old. It is also one of the largest hardwood trees,
usually growing 60 to 100 feet tall, but sometimes larger. A longlived Sycamore tree can reach six hundred years.
Physical Characteristics:
The American Sycamore is identifiable by its broad, maple like
leaves and a trunk and limb complexion of mixed green, tan and
cream, which some suggest it looks like camouflage.
Trunk | Bark: The most striking feature of this tree is the way its
bark readily exfoliates. The outer bark flakes off in great irregular
masses leaving the surface mottled in a patchwork of tans, whites,
grays, greens and sometimes yellows. Some suggest it looks like
camouflage. The inner bark is usually smooth. It often divides into
two or more trunks near the ground and its massive branches form a wide,
irregular crown. Sometimes the smaller limbs look as if whitewashed.
The explanation for the camouflage trunk is found in the rigid texture of the bark
tissue, which entirely lacks the expansive power common to the bark of other
trees, so it is incapable of stretching to accommodate the growth of the wood
underneath.
Leaf: broad, maple like leaves. palmate (like a hand) with three to five lobes
(sections, like fingers). The edge of the leaf is wavy, with teeth. The top of the leaf
is bright green, and the underside is pale green. They have a long petiole
(leafstalk). Like all deciduous trees, American Sycamores lose their leaves in the
fall. However, you can still identify them by their bark.
Flower : Monoecious; imperfect, both male and females are very small and
appear in dense round ball-shaped clusters, typically a single cluster to a stalk,
appearing with the leaves. They start out green before turning a deep red.
Fruit: A spherical multiple of achenes borne on a 3 to 6 inch stalk. Each seed is tiny, winged, and 1/2 inch long;
maturing in November, disseminating in late winter. The fruits of American Sycamore are one inch brown balls
which hang on stalks. They often litter yards and sidewalks when they fall, although some stay on the tree through
the winter. Some people call them "buttonballs."
Seeds: The seeds, which are packed tightly together inside the fruit, are called "achenes." Achenes are dry, hairy
fruits. Achenes, because of their light "hairyness," can travel far on the wind, or float on water, to grow trees in new
places. The seeds are also dispersed (spread) by birds and other animals which eat them and poop some out in new
places. They can still grow into new trees!
Twig: Sycamore twigs are thin and green, and they zigzag; leaf scar surrounds the bud and the stipule scar surrounds
the twig; terminal bud is absent; lateral buds are reddish, resinous, with a single, cap-like scale.
Life Span
It is a member of one of the planet's oldest clan of trees, Platanaceae. Paleobotanists have dated the family to be over
100 million years old. A long-lived Sycamore tree can reach six hundred years. The deciduous sycamore is fast
growing and sun-loving, "growing seventy feet in seventeen years" on a good site.
It is a fast-growing and long-lived tree of lowlands and old fields.
Ecological Characteristics
American Sycamores are found in forests, but its native range is often found in riparian and wetland areas such as
the edges of streams, lakes, and ponds, as they like moist alluvial soil.
Sycamores naturally grow in groups with Silver Maple, Red Maple, Yellow
Poplar, Sweetgum, and Black Willow.
Distribution Range: The range extends from Iowa to Maine in the north,
Nebraska in the west, and south from Texas to the northern tip of Florida.
Sometimes grown for timber, it has become naturalized in areas outside its
native range.
Diseases: The American sycamore is susceptible to Plane anthracnose
disease, a fungus. Although rarely killed or even seriously harmed, American
sycamore is commonly partially defoliated by the disease, rendering it
unsightly as a specimen tree. The disease makes its appearance soon after the
leaves have expanded, appearing in the form of small black spots which lie
close to the veins. As a result, the half grown leaves turn brown, shrivel, and
fall. It is very common in early July to see these trees putting forth their
second crop of leaves while the first hang brown, dead, and unsightly on the
ends of the branches. Susceptibility to the Plane anthracnose disease, which renders it unsightly, has resulted in the
American Sycamore not being planted as often.
Ecological Role & Relationship With Other Species
Numerous wildlife species eat the American Sycamore achenes and s well as utilizing make their home depend
American Sycamores usually become hollow as they get older. A few animal species known to live inside hollow
trees are Pileated Woodpeckers, Barred Owls, Great Crested Flycatchers, Chimney Swifts, and Raccoons.
Humans typically use the American Sycamore for landscaping, along streets and in yards as a shade tree. Sycamore
is also valuable for timber and is also widely planted as a shade tree because of its distinctive white, exfoliating bark
and broad, dense crown. Recently, it has become a favored species for use in intensively cultured "biomass farms" in
the Southeastern United States.
Other interesting facts
• One of the 100 most common North American Trees
• It is the only species in the Plane Tree family that is native to Illinois.
• The terms under which the New York Stock Exchange was formed are called the "Buttonwood Agreement",
because it was signed under a buttonwood (sycamore) tree at 68 Wall Street, New York City, in 1793.