I haven't managed to take a photograph, but the big leaf magnolia (Magnolia macrophylla) near the back gate to the Arboretum is impressive at the moment. It's in full flower. The large white flowers are striking, and the tree is getting to be a good size.
Big-leaf magnolia has a limited range in nature, occurring in a small area between Rock Hill, SC and Charlotte, NC. Andre Michaux 'discovered' it, and it's among the many species he named.
But it makes an excellent garden tree (we have one in our home garden), and we have a number of them in the Garden. (You'll see their offspring, too, in areas far from the parent trees, thanks to bird dispersal).