What, if anything, is a species? Part 1

Two trees grow next to each other in a woods in the Bluegrass region of Central Kentucky.  Can you identify them?   Are these two different species or one?  Post your answers in the comments below or on Facebook, then tune in for a discussion of these pictures tomorrow.  Over the next couple of weeks, we will be discussing the species concept as it pertains to trees.  This is the first installment.

photo of two trees
Two trees in the woods

Note: The title of this article is a reference to a chapter by Steven J. Gould, “What, if anything, is a zebra.” From Gould, S.J. 1984. Hen’s Teeth and Horse’s Toes, W.W. Norton, Co., New York.