seems, 



PREFACE. 



VIU 



superbly illustrated with lithographs printed in color from drawings by Isaac Sprague, 



was publislied in 1875. i ■ ^ -n .- i ^ - 



An account of the literature on the subject, however brief, will not be complete 



without mention of Mr. M. A. Curtis's Woody Plants of North Carotnu, of the val- 



uable notes on the native trees of the lower Wabash River in Indiana and Illinois by 



Mr. Robert Ridgway, of the paper on the forest trees of British Columbia b)- Mr. 



George M. Dawson, and of Professor Edward L. Greene's account of some of the Oaks 



of California. 



The line AvMch divides trees from shrubs is a purely arbitrary one, and an attempt 



to separate them is often unsatisfactory. A division based on liabit rather than on ^ize 

 ,, upon the whole, more easily apphed than any other, and therefore less objection- 

 able. So, for the purposes of this work, I have considered as trees all woody plants 

 which grow up from the ground with a single stem, excluding all such as habitually 

 branch at the ground into a number of stems, whatever size or height they may attain. 

 The forests, of North America exclusive of Mexico, the region embraced in this work, 

 are now beheved to contain four hundred and twenty-two species of plants, besides 

 numerous varieties, which, under the rule adopted, can fairly be cousidercd trees. 



The sequence of the orders and of the genera adopted in the first volumes of this 

 work is that of the Genera Plantarum of Bentham & Hookei', and of the standard 

 botanical works published in the United States. 



The question of nomenclature, which is beginning to occupy the attention of bota- 

 nists more seriously than ever before, is perplexing. I have adopted the method A\liicli 

 imposes upon a plant the oldest generic name applied to it by Linnaeus in the first 

 edition of the Genera Plantarum, published in 1737, or by an}" subsequent author, and 

 the oldest specific name used by LinnEEUS in the first edition of the Species Planfarumj 

 published in 1753, or by any subsequent author, Avithout regard to the fact that such 

 a specific name may have been associated at first with a generic name improper!}' em- 

 ployed. The rigid application of this rule leads to the change of many fiuniliar names 

 and considerable temporary confusion. But unless it is adopted, anytliing like stability 

 of nomenclature is hopeless, and the sooner changes which are inevitable in the 

 future are made, the more easily students will become accustomed to them and acquire 

 a knowledge of the correct names of oiu* trees. 



Unless other sources of information are specially mentioned, the figures represent- 

 ing the specific gravity and the weight of the wood of the different trees described in 

 this work are taken from the Report on the Woods of the United States, published in 

 Yolume IX. of the Final Reports of the Tenth Census. In most cases these are averages 

 from several specimens, obtained, as far as possible, from trees groAving under different 

 conditions in diff-erent parts of the country. The specific gravity is calculated from 

 specimens of wood from Avhich all moisture was artificially expelled ; the weight of the 



cubic foot is that of wood seasoned naturally and containing, therefore, mote or less 

 moisture. 



No one can realize more clearly than I that the chief value of this new Silva is due 

 to the accuracy and beauty of the drawings, upon which my associate, Mr. C. E. Faxon, 



