4 PREFACE 



combinations are indicated as are other synonyms. Common 

 names have been used sparingly, for it has not been deemed 

 wise to propose them when they are not already in general use. 



The area covered can be outlined somewhat more exactly than 

 in the previous edition, as the natural boundaries of our floras are 

 now better understood, which do not always coincide with the 

 boundaries of States and Territories. The purpose has been to use 

 Colorado as the center of the flora included in the manual, and to 

 present complete the flora of that State, of Wyoming, of Yellow- 

 stone Park, and of the Black Hills of South Dakota; also to in- 

 clude most of Montana, southern Idaho, the eastern half of Utah, 

 and the northern half of New Mexico and adjacent Arizona. 

 Naturally the manual will also cover fairly well an indefinite 

 border to the territory outlined. 



It is not possible to acknowledge all the sources of information 

 in the preparation of a manual, but the following list of authors 

 may be cited, from whose publications, descriptions and keys 

 have been obtained: LeRoy Abrams, L. H. Bailey, N. L. Britton, 

 F. V. Coville, M. L. Fernald, L. N. Goodding, Asa Gray, E. L. 

 Greene, J. M. Greenman, H. M. Hall, Thomas Howell, W. L. 

 Jepson, Elias Nelson, C. V. Piper, B. L. Robinson, J. N. Rose, 

 P. A. Rydberg, J. K. Small, William Trelease, Sereno Watson, 

 and many others. 



JOHN M. COULTER. 

 THE UNIVERSITY OF CHICAGO. 



Ever since Professor Coulter invited me to undertake the re- 

 vision of his well known Manual I have had his advice and en- 

 couragement. The work has gone through the press under his 

 direct supervision, and all of the proof sheets have passed through 

 his hands. I take great pleasure, therefore, in acknowledging my 

 indebtedness and in expressing my gratitude for his courtesy and 

 helpfulness. If this new edition serves its purpose as well as the 

 first, a large measure of credit must be given to Professor Coulter. 

 For any errors that the book may contain, I assume entire re- 

 sponsibility, 



AVEN NELSON. 

 THE UNIVERSITY OF WYOMING. 



