Backyard Gardening: The Sycamore: Is It More Sick, or Not?
Kathryn Dorman
If you look at the trunk of a sycamore tree, especially in autumn, you might think that the tree is really sick. The bark is flaking off, more at the top than at the bottom. The tree trunk has a mottled appearance as if its bark has a rash! Is the tree dying? Should you call the tree surgeon or fire up the chainsaw? No, probably not. This is the normal appearance of a healthy sycamore tree (See Photo 1).
The American sycamore (Platanus occidentalis) is a member of the planetree, or sycamore (Platanaceae) family. It is also called eastern Sycamore, American planetree, buttonwood, or buttonball tree. American sycamore is native to eastern North America. According to the U.S. Department of Agriculture/U.S. Forest Service (USDA/FS), “Sycamore grows in all states east of the Great Plains except Minnesota. Its native range extends into extreme southern Ontario, and it can also be found in the mountains of northeastern Mexico.”
(https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/platanus/occidentalis.htm).
According to the Lady Bird Johnson Wildflower Center (WFC) in Austin, Texas, the American sycamore is a deciduous tree that can grow to a height of 75 to 100 feet. The tree canopy, with an open crown of huge, crooked branches, is typically only slightly less wide than the tree is tall. Sycamore is one of the largest hardwood trees, by diameter, in North America. It can have a trunk diameter of 10 or more feet. The bark of large, old trunks flakes off in scales or plates, exposing the smooth, cream-colored inner bark. From a distance, a grove of sycamores may be mistaken for birch trees, with their horizontally flaking, white or light gray bark. Keep in mind, however, that sycamores, on average, will be much larger, and the leaves will be markedly different in shape.
Sycamore leaves are shaped like maple leaves but are typically much larger. They grow alternately along branches, while maple leaves grow oppositely, in pairs (See Photo 2). Sycamore is monoecious, with separate male and female flowers occurring on the same tree. Globular fruits (buttonballs) often remain on the tree through December (https://www.wildflower.org/plants/result.php?id_plant=ploc).
The aggressive root systems of sycamore trees will be widespread and strongly branched (USDA/FS).
The American sycamore will grow in full sun to partial sun. It prefers moist, deep, rich soils, but can adapt to a wide variety of soils. Sycamores will reach their largest size when plenty of moisture is available, as is the case near rivers, lakes, and streams. Sycamores will not do well in flooded areas; they will die if entire trees are submerged for more than two weeks (USDA/FS).
According to the University of Illinois Extension Office (UIE), the American sycamore is known for its exfoliating bark, which creates a camouflage-like appearance. Until I did the research for this article, I never thought of sycamore bark as resembling camouflage, but now I wonder how I missed it! “In most cases, shedding bark on a sycamore may actually be a sign that the tree is extremely healthy and growing rapidly (https://extension.illinois.edu/blogs/garden-scoop/2018-07-18-sycamores).”
The inner bark is growing more quickly than the outer bark, pushing it out of the way. Sycamores grow rapidly throughout their life span, which can exceed 250 years!
American sycamore trees can be used as shade trees or as focal points in large open areas. They should not be used as street trees, or as shade trees for small lawns. Due to their rapid growth rates, “sycamores are recommended for [reclamation] planting on all types of coal-stripped land in many of the Northeast and Central United States (USDA/FS).” “Sycamore wood is used for furniture parts, millwork, flooring, and specialty products such as butcher blocks, as well as pulpwood, particleboard, and fiberboard (WFC).” Fun fact: the biblical tree of life in the Garden of Eden is believed to have been the sycamore.
According to Penn State Extension, sycamores are susceptible to sycamore anthracnose, caused by the fungus Apiognomonia. This fungus infects the tree as young leaves unfurl. Leaves and ends of twigs die back. Dead areas develop on the tree trunk and main branches, but new buds and then leaves will form. This results in a “‘witches’ broom’ proliferation of branch ends, and an overall contorted branching pattern across the tree canopy.” A cool, wet spring will encourage the development of anthracnose. Most trees will recover from this infection, but they may be weakened enough to become susceptible to other diseases. Also, “frost damage can both mimic and complicate anthracnose symptoms (https://extension.psu.edu/mysteries-of-our-native-sycamore).”
I would be hard-pressed to find a place for a potentially huge sycamore tree in my yard. I would be concerned about the sycamore’s roots heaving my sidewalks or driveway, not to mention getting into my septic system or under the foundation of my house. The clean-up of the dead branches, large leaves, and seed balls would be rather messy, too. Since they’re easy to spot, I think I’ll stick with looking for sycamore trees in the forest.
Kathryn Dorman has been a Penn State Extension certified Master Gardener
of Clinton County since 2017. She can be reached at clintonmg@psu.edu, or
through the Clinton County Master Gardener Hotline at (570) 858-0198.
