Quercus cerris | Stanford
Consulting tree identification books, it became clear this tree was Quercus cerris, the Eurasian Turkey Oak (Eurasian is specified here, because, as typical with common names for plants, they repeat in different places, apply the name to totally different plants - there is another Turkey Oak in the southeastern United States.) Q. cerris is quite variable in leaf form. Despite that variation, years of observation of this particular tree suggest that it is a hybrid from New York, where the tree was originally grown. White Oak (Quercus alba) is common there, and the leaves of this tree, along with the overall growth habit, suggest Q. alba introgression.