211 



Professor Preston, who is Associate Professor of Forestry in 

 the Colorado State College, has made use of the best possible 

 resources in the preparation of his book. For example, the plates 

 for the conifers, with four exceptions, were made from drawings 

 used in Sudworth's bulletins on the trees of the Rocky Mountains. 

 The distributional maps accompanying the descriptions of each 

 species were referred to government, experiment station and col- 

 lege experts. "The description of genera and species are based 

 largely on material secured from the sources listed under the 

 selected bibliography." A point which appeals strongly to the 

 writer is that the descriptions include not only the botanical char- 

 acters of the species, but also silvical characters, such as habitats, 

 tolerance, in many cases the character of the root system, enemies, 

 reproduction and associates. 



The following states and parts of states are included in the 

 author's delimitations of the Rocky Mountain region ; Montana, 

 Idaho, Wyoming, Colorado, Utah, Nevada, Arizona, New Mexico, 

 extreme western Texas, and the Black Hills of South Dakota. 

 Further there is a list of trees found in each state. A key to the 

 genera follows, and throughout the book, keys to the various species 

 within certain genera. 



In addition, there is a description of the six life zones or belts 

 -occurring in the Rocky Mountain region, as well as several pages 

 devoted to the explanation of "tree characters." A glossary of 

 botanical terms and a bibliography and index conclude the book. 



Further, to conform to the title of the book, not only are the 

 trees of the above mentioned states included, but also those of the 

 adjacent Rocky Mountain region of Canada, even extending into 

 Alaska — truly a vast area. Such species (which do not occur in 

 the U. S. Rockies at all, but extend from the eastern U. S. into 

 the Canadian Rockies) are, for example, the Balsam Fir, the White 

 and the Black Spruces, the Jack Pine, Eastern Larch, etc. Thus 

 252 species representing 85 genera and 40 families have been 

 treated, as well as numerous varieties. 



This review is being written in a far off, little-known spot on 

 the Maine coast, where no reference books are available, but we 

 believe that we are not making a rash statement in saying that this 

 number of tree species (252) is several times greater than the 

 number of those in all Northern Europe. 



