INTRODUCTION xxi 



the American tree. Mr. Sargent substituted the name of 

 the author, and it now stands ''Ulmus Thomasi, Sarg.** 

 Occasionally a generic name is changed. The old generic 

 name becomes the specific name. Box elder was formerly 

 known as ''Negundo aceroides, Moench." It is changed 

 back to ''Acer Negimdo, Linn." On the other hand, the 

 tan-bark oak, which is intermediate in character between 

 oaks and chestnuts, has been taken by Professor Sargent 

 in his Manual, 1905, out of the genus Quercus and set in a 

 genus by itself. From ''Quercus densifiora, Hook, and 

 Arn*" it is called "Pasania densiflora, Sarg.," the specific 

 name being carried over to the new genus. 



About one hundred thousand species of plants have been 

 named by botanists. They beheve that one half of the 

 world's flora is covered. Trees are better known than less 

 conspicuous plants. Fungi and bacteria are just coming 

 into notice. Yet even among trees new species are con- 

 stantly being described. Professor Sargent described 567 

 native species in his "Silva of North America," published 

 1892-1900. His Manual, 1905, contains 630. Both books 

 exclude Mexico. The silva of the tropics contains many 

 unknown trees, for there are still impenetrable tracts of 

 forest. 



The origin of local names of trees is interesting. History 

 and romance, music and hard common sense are in these 

 names — likewise much pure foolishness. The nearness to 

 Mexico brought in the musical piflon and madrofia in the 

 southwest. Pecanier and bois d'arc came with many other 

 French names with the Acadians to Louisiana. The In- 

 dians had many trees named, and we wisely kept hickory, 

 wahoo, catalpa, persimmon, and a few others of them. 



Woodsmen have generally chosen descriptive names 



