I can always spot a sycamore, however, and I suspect most people can. Their branch structure is elegant and unique, but it's the lovely mottled bark that's the dead giveaway. As an added bonus, to my way of thinking, they have large leaves. I'm a sucker for large leaves; I can't resist making heliographic prints of them:
With a big leaf like this, it's important to make the print on a hot sunny day with low humidity, so that the paint wicks out from under the leaf quickly and leaves a good image. You can see I was successful in this instance; the leaf is drying out and lifting up from the fabric, and you can see the outline of it, especially on the right side of the photo.