Sycamore (Platanus occidentalis) (American planetree, buttonwood, American sycamore, button-ball tree) is one of Iowa's largest trees; it attains diameters of 4-7 feet and heights of over 100 feet. It usually develops into a tree with a long, clear, strong central stem with spreading branches forming an open crown with somewhat sparse foliage. Its unusually large leaves, round seedballs, and mottled bark make it one of the easiest tree to identify.
Habitat: Grows on bottomland sites, primarily in the southern and eastern part of the state.
Hardiness: Zones 4 through 9
Growth Rate: Moderate to Fast
Mature Shape: A large tree with a massive trunk and a wide spreading crown with large, crooked branches.
Height: 75-100 feet or greater
Width: 75-100 feet or greater
Site Requirements: Prefers deep, moist, rich soil. Sycamores are found growing naturally in bottomlands, and banks of rivers or streams.
Leaves: Alternate, simple, lobed, with pointed tips
Flowering Dates: March - April
Seed Dispersal Dates: February - April
Seed Bearing Age: 10 years
Seed Bearing Frequency: Yearly, late spring frosts can kill seeds
Seed Stratification: No stratification period is needed.
Sycamore is native to most of the eastern US, except for most of Wisconsin and all of Minnesota. It is native to the south east two thirds of Iowa. It grows best on moist soils, often found along streambanks and on bottomlands. However, it does adapt and grow on drier soils, although best growth is obtained on more moist sites. Sycamore is usually a minor component of bottomland forests in Iowa. It is usually the minor associate of willow, cottonwood, and silver maple. Sycamore is an easy tree to propagate using hardwood cuttings collected during the late winter.
The leaves of sycamore are alternate, simple, 4-7 inches long, light green in color, palmately 3-5 lobed, with coarse teeth on the margins. The undersurface of young leaves are covered with tufts of white woolly hair. The terminal bud is absent, while the laterals are large, (1/4-3/8" long), blunt pointed, smooth, shiny, dark reddish brown with a single visible scale. The buds are enclosed within the petiole base of the leaves and are exposed when the leaves fall. The young stems of sycamore are rather stout, round, smooth, shiny yellow-orange-brown in color, and have a zigzag growth pattern. The bark on upper branches is either smooth and chalk-white in color or mottled with thin, irregularly shaped patches of white or tan; older bark on lower trunks is light to dark gray to reddish brown plates. The seed ball is single, 1 inch in diameter on a slender 3-6 inch long stem. The fruit is composed of multiple achenes or dry individual one seeded fruits.
The wood of sycamore is moderately hard, heavy, strong and resistant to shock. It is not durable, and should not be used where exposed to moisture of conditions favoring decay. The primary uses are for veneer, boxes, flooring, boxes, pallets, crates and butcher blocks because it is very difficult to split.
Sycamore has often been planted as a shade or street tree in Iowa because of its fast growth, excellent shade, handsome appearance, and its ability to withstand winds. It has strong wood and lives much longer than many other fast growing trees. It is less hardy in northern and northwest Iowa, and often suffers some twig dieback in these locations. Throughout Iowa, the major disadvantage of sycamore as a landscape tree is the fungal disease, anthracnose. The extent and severity of the disease varies with the spring weather; the cooler and wetter springs usually are associated with greater problems with anthracnose. Anthracnose is seldom fatal, but results in leaf, bud, and small twig death. Varieties and hybrids of sycamore and the London Plane tree may be more resistant to anthracnose.