The American Sycamore:
A Ghost of a Tree
Master Gardener Scoop – December 6, 2017
By Linda Summers,
One of the easiest trees to identify during the fall and winter months when most trees have lost their leaves is the American Sycamore, or Platanus occidentalis. It has also been called the American Planetree, Buttonwood or Buttonball-tree. Sycamores are the sole members of the Family Platanaceae. Interestingly, in England they are “planes” and the sycamore goes by the synonym of Acer pseudoplatanus, translating to be “the false plane maple.” Indeed, the leaf of an American sycamore looks very much like a maple leaf.
The word “plane” derives from the Greek word for “broad”, referring to the leaf.
The leaves are simple, alternate, palmately veined and frequently broader than they are long. The 4-9″ wide leaves are a shiny green on the upper surface and a paler green underneath. They have three to five lobes and have the distinction of being the largest single-bladed leaf native to the American forest. Despite the fact that it is quite an impressive sight, it is not always considered a good landscape tree because of its massive size and messy habit of constantly dropping leaves, twigs and fruits. However, the trees generally tolerate urban air pollution.
The American sycamore grows 75-100′ in height and can be quite massive in its trunk and open crown of crooked branches. It was first recognized in the United States in 1640 and ranges from Maine to Ontario and Minnesota, then south to Florida and Texas. You can find it in bottomlands and along the banks of rivers and streams, as it mostly prefers moist, rich soils.
I personally look for sycamores in the woods because their handsome white mottled bark stands out against the darker browns, grays and blacks that characterize many other trees. It has been called the “ghost tree” by some people which adds to its eye-catching appearance. The bark of young to moderately old trees has large, thin plates which peel off the trunk, exposing the inner bark with shades of creamy white, yellow or green. This may be caused by the inability of the tree bark to stretch with the expanding trunk and limbs.
The single buttonball fruits on an American sycamore hang on a long slender stem during the winter and break up into many hairy nut-like seeds in the spring. One of the characteristics that distinguishes the American sycamore from the Oriental sycamore (P. orientalis) or London plane (P. acerifolia) is that while the American sycamore has single seed balls, the other two trees have seed balls that hang in pairs or even fours. The American sycamore and the London plane tree are frequently confused, but remember that the sycamore has the larger, longer-stalked, single fruit ball and typically a shallowly three-lobed leaf.
Diseases and insects that can affect sycamores include anthracnose, leaf spots, aphids, Sycamore tussock moth, scales, bagworms, borers, etc. During March to May when the weather is cooler and wetter, anthracnose, a fungal disease, can be a problem affecting developing leaves and stems. The disease kills off the emerging growth, giving the appearance that the tree is leafing out late. The fungus can be spread by rain drops, as well as birds’ feet landing on an affected area. There is dieback, normally followed by a “witches’ broom”, clusters of unaffected leaves. Typically, the tree recovers and leafs out again in late June to early July and the disease is not life-threatening.
Commercially the American sycamore is important because its wood is moderately heavy, hard and coarse-grained. It is used for furniture, boxes, crates and butcher’s blocks. Native Americans used the trees for dugout canoes.
The American sycamore is truly one of the more impressive trees in our landscape. For more information, please contact your local Master Gardener or call or visit your local University of Illinois Extension Office. Another great source of gardening information is the Extension website at web.extension.illinois.edu.