For a good source for identifying hickory trees ( and of course many other trees) get a copy of David Allen Sibley's new book, "The Sibley Guide to Trees. It is one of the best books of its type that I have ever come across. Ever tried to identify a hickory from its leaves, nuts or bark? It isn't easy. The hickories also just love to confuse us poor humans by changing their leaf configurations from time to time. Shagbarks, Shellbarks and Mockernuts are very good at this game. However, Sibley covers this in his book and gives the reader pictures to identify nuts, twigs, leaves, bark and maps where the various types tend to grow. Well worth acquiring a copy even if you don't try to make hickory syrup.
al--Thanks for the book info. I really had lowered my expectations on ID after reading at U VA that many hybridize. And after trying to ID my own backyard hickory. (Its a few years old, eight feet tall and has some leaves with 11 leaflets which confuses me. ) Now I am encouraged.
Fitsy-- the one called bitternut makes me nervous!
My Dad is forever more going into detail about what each of his hickories in his woods will produce. He calls one a pignut, says it is bitter, can be eaten but he rather the pigs eat them (this is from his young days when thier pigs roamed the woods).