Hi, I originally saw a sapling in a park in Philadelphia, PA and the rectangular 3 dimensional outgrowths of bark were very unusual. Then I saw a full grown tree in Burlington NC and found these seed pods in the area, although I’m not sure they are from the same tree. What is this tree? Lynn
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Hi Lynn, thanks for writing! The outgrowths you saw on the bark of the sapling in Philadelphia and the ones visible in your photo of the tree in North Carolina and indeed unusual. They are called “wings” and only a few plants have them. There are three that I think are relevant to your question. One is burning bush (Euonymus alatus), which is an Asian bush/tree that was introduced as an ornamental in North America and is now widespread and considered invasive. Two others are the winged elm, (Ulmus alata), and the sweetgum tree (Liquidambar styraciflua), which also hsa wings. These three species are from three different orders, and therefore not closely related, so they almost certainly evolved wings separately. I haven’t found a good explanation for what the purpose, if one exists, for the wings. It’s possible they strengthen the branches. I’m going to see if I can contact a botanist or two to see if there are theories on a function for these wings.
If anyone can point me to an expert on this subject, please email me at firstname.lastname@example.org.
As to which of these three you likely saw, both the winged elm and sweetgum are native to the southeastern U.S. states, with ranges that stop short of Pennsylvania. However, they have been planted outside their range, so it’s possible that you saw a sapling of one of these in the park in Philadelphia. It seems more likely to me that you saw a young burning bush, which can be found throughout the east, especially the northeast of the U.S. and in Ontario, Canada.
Moving to the photo you supplied, that looks like a sweetgum tree, and the spiky seed ball you found is convincing evidence. That is definitely a sweetgum seed pod. So it’s possible you saw two different species, but because of the wings, they seem similar. Tom
As a forester and “victim” of dendrology classes when back in forestry school, I agree that Tom has zeroed in nicely.
Given the size, shape and color of the buds in the photos, it looks like sweetgum (Liquidambar styraciflua) to me. And that name is just wonderful to say out loud!