PREFACE TO THE SECOND EDITION 



THE studies of the trees of North America (exclusive of Mexico) which have been carried 

 on by the agents and correspondents of the Arboretum in the sixteen years since the publi- 

 cation of the Manual of the Trees of North America have increased the knowledge of 

 the subject and made necessary a new edition of this Manual. The explorations of these 

 sixteen years have added eighty-nine species of trees and many recently distinguished 

 varieties of formerly imperfectly understood- species to the silva of the United States, and 

 made available much additional information in regard to the geographical distribution of 

 American trees. Further studies have made the reduction of seven species of the first edi- 

 tion to varieties of other species seem desirable; and two species, Amelanchier obovalis and 

 Cercocarpus parvifolius, which were formerly considered trees, but are more properly 

 shrubs, are omitted. The genus Anamomis is now united with Eugenia; and the Arizona 

 Pinus strobiformis Sarg. (not Engelm.) is now referred to Pinus flexilis James. 



Representatives of four Families and sixteen Genera which did not appear in the first 

 edition are described in the new edition in which will be found an account of seven hundred 

 and seventeen species of trees in one hundred and eighty-five genera, illustrated by seven 

 hundred and eighty- three figures, or one hundred and forty-one figures in addition to those 

 which appeared in the first edition. 



An International Congress of Botanists which assembled in Vienna in 1905, and again in 

 Brussels in 1910, adopted rules of nomenclature which the world, with a few American ex-, 

 ceptions, has now generally adopted. The names used in this new Manual are based on 

 the rules of this International Congress. These are the names used by the largest number 

 of the students of plants, and it is unfortunate that the confusion in the names of American 

 trees must continue as long as the Department of Agriculture, including the Forest Service 

 of the United States, uses another and now generally unrecognized system. 



The new illustrations in this edition are partly from drawings made by Charles Edward 

 Faxon, who died before his work was finished; it was continued by the skillful pencil of 

 Mary W. Gill, of Washington, to whom I am grateful for her intelligent cooperation. 



It is impossible to name here all the men and women who have in the last sixteen years 

 contributed to this account of American trees, and I will now only mention Mr. T. G. Har- 

 bison and Mr. E. J. Palmer, who as agents ofthe Arboretum have studied for years the 

 trees of the Southeastern States and of the Missouri- Texas region, Professor R. S. Cocks, of 

 Tulane University, who has explored carefully and critically the forests of Louisiana, and 

 Miss Alice Eastwood, head of the Botanical Department of the California Academy of 

 Sciences, who has made special journeys in Alaska and New Mexico in the interest of this 

 Manual. Mr. Alfred Rehder, Curator of the Herbarium of the Arboretum, has added to 

 the knowledge of our trees in several Southern journeys; and to him I am specially indebted 

 for assistance and advice in the preparation of the keys to the different groups of plants 

 found in this volume. 



This new edition of the Manual contains the results of forty-four years of my continuous 

 study of the trees of North America carried on in every part of the United States and in 

 many foreign countries. If these studies in any way serve to increase the knowl- 

 edge and the love of trees I shall feel that these years have not been misspent. 



C. S. SARGENT. 

 ARNOLD ARBORETUM 



September, 1921 



