The trees at the arboretum usually have some form of identification nearby as you can see below. This species of platanus is also known as the American sycamore, American planetree, occidental plane, and buttonwood. Although they grow as far north as the extreme south of Canada, this one at the arboretum is the only one I have ever seen.
The mottled bark often flakes off, one of the means used to identify this tree.
@kansuze