Guide to the Trees, Shrubs, and Woody Vines of Tennessee
B. Eugene Wofford and Edward W. Chester
The University of Tennessee Press.
This book is out of print, but still useful! Check out your local used bookstores or an online source like AbeBooks.
To select from a dropdown list of genera, type only the first 2-3 letters.
If "briar" doesn't deliver the results you want, try an alternate spelling such as "brier", etc.