4 PREFACE TO FIRST EDITION. 
Flora of the United States” (Britton & Brown); the publica- 
tions of the Division of Forestry of the Department of Agri- 
culture; “Baume und Striucher des Waldes” (Hempel & Wil- 
helm); and Flora von Deutschland, Oesterreich u. d. Schweiz 
(Prof. Dr. Thome). 
S. B. G. 
University of Minnesota, 
St. Anthony Park, 
July 20, 1808. 
