6 PREFACE 



Scientific names are marked so as to indicate the pronuncia- 

 tion. The vowel of the accented syllable is marked by the grave 

 accent (') if long, and by the acute (') if short. 



In the preparation of this book the author has received much 

 valuable aid. His thanks are especially due to the authorities 

 of the Arnold Arboretum, Boston, Massachusetts, and of the 

 Missouri Botanical Garden, St. Louis, for information in regard 

 to the hardiness of species; to Mr. John H. Redfield, of the 

 Botanical Department of the Philadelphia Academy of Nat- 

 ural Sciences, for books, specimens from which to make illus- 

 trations, etc. ; and to Dr. A. C. Stokes, of Trenton, New Jersey, 

 for assistance in many ways, but especially for the accurate 

 manner in which he has inked the illustrations from the au- 

 thor's pencil-drawings. 



The author also wishes to acknowledge the help received 

 from many nurserymen in gathering specimens for illustra- 

 tion and in giving information of great value. Among these, 

 special thanks are due to Mr. Samuel C. Moon, of Morrisville 

 Nurseries, who placed his large collection of living specimens 

 at the author's disposal, and in many other ways gave him 

 much intelligent aid. 



