xiv INTRODUCTION. 



made to explain why two different standards are used in the same 

 work. The altitudes are those at which the different species grow 

 within the state of Colorado, so far as records show. Ma,ny of the 

 plants which grow at an altitude of 14,000 feet in Colorado, grow 

 at sea-level along the arctic coast. 



The nomenclature used is in principle agreeing with the so-called 

 American Code adopted at a meeting in Philadelphia, printed in the 

 Bulletin of the Torrey Botanical Club in May, 1904, and submitted to 

 the International Botanical Congress at Vienna last summer, with 

 a few modifications resulting from a compromise with the European 

 botanists. This code as modified is now followed by a majority of 

 the leading systematic botanists in this country. The fundamental 

 principle underlying is that the selection of generic as well as specific 

 names should always be governed by the priority of publication. The 

 European botanists have adopted this principle as far as specific 

 names are concerned, but most of them are not yet willing to apply 

 the same rules to generic names. In the older publications on the 

 Rocky Mountain flora the so-called Kew Rules were adhered to, 

 which after all gave very little consideration to priority. Many of 

 the names in this catalogue will be unfamiliar to some of its users, 

 but in most cases the old names are given as synonyms in italic and 

 also in the index. In the index there has been inserted also a few 

 common names not given in the text followed by the equivalent latin 

 generic name in parenthesis. Most of these are local names un- 

 known to the author before they appeared in a recent publication on 

 western botany. 



With regard to generic limitations, the author belongs to that 

 radical school which believes in small genera with closely related 

 species rather than in larger ones with a heterogeneous mass of 

 different groups of plants having relatively little relationship to each 

 other. Many of the older genera have therefore been divided. The 

 division of genera as well as species has gone perhaps a little further 

 than many would think advisable, but the author has tried to be con- 

 sistent in his work. 



The author has not published any new species or genera in this 

 work. He has also tried to avoid the publishing of new names or 

 new combinations of names. Anything that had not been published 

 before, the author has endeavored to publish in the Bulletin of the 

 Torrey Botanical Club while the catalogue was being set in type. 

 The reasons for so doing are the following : ( i ) The publication of 

 technical descriptions should be limited to technical books and peri- 



