365 Urban Species. #284: Sweetgum

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Photos by cottonmanifesto. Location: the Riverway, near Landmark Center, Boston.

Urban species #284: Sweetgum Liquidambar styraciflua

Star shaped leaves turning an array of colors, and branches decorated with spiky spheres. That's the sweetgum tree. It's a popular choice in city parks across the eastern United States and California. Sweetgum is not especially cold tolerant, and Boston is about as far north as it will survive. This tree is native to North America, Mexico, and South America, and closely related species occur in China, and Turkey. Sweetgum trees are named for their sap, which has been used for various medicinal purposes, and reportedly, as a chewing gum. Modern experimenters have little positive to say about this last use.

Different varieties of sweetgum have been cultivated for their foliage, which can vary from yellow to red to purple in autumn, and can retain their leaves later than other deciduous trees. One sweetgum tree we saw one November in London seemed to have leaves of every fall color imaginable. The spiked balls that appear at the end of summer are the fruit of the sweetgum. Inside the tough green hide, seeds develop. Later it becomes woody, and the winged seeds are released from holes that form when the spikes open like tiny beaks. Sweetgum seeds are eaten by birds and squirrels. The fruit also contains a chemical which is the source for the antiviral drug Tamiflu, of interest recently because of avian flu concerns.