Identifying tree species can be challenging when the traits typically used to describe them—leaves, buds, and twigs—are not clearly visible or, in the case of leaves, not even present. On Saturday, September 29, from 9 – 1, join Michael Wojtech, author of Bark: A Field Guide to Trees of the Northeast, for an exploration of bark, the tree characteristic that provides clues in every season. You will learn how to differentiate six different bark types, how to use the book’s identification keys, and begin to discover why such a variety of bark characteristics has evolved—Why do some species have smooth bark, while on others it is thick and broken? Why does bark peel? After a classroom session you will practice identifying native tree species on the grounds of the Arboretum. Open to naturalists at all levels of experience. Bark: A Field Guide to Trees of the Northeast is required for the class and can be purchased at the time of registration. Purchased books will be distributed in class. Birch bark photo from www.fondofsnape.com. Fee: $40 member, $55 nonmember and $17.00 per book. Register at www.arboretum.harvard.edu.