PREFACE 



During the summer of 1906 I was employed by the Depart- 

 ment of Botany of the University of Missouri to collect plants 

 in Colorado for the Herbarium of the University. I spent, 

 therefore, a period of two months and a half in this work. I 

 arrived at Boulder, Colorado, June eighteenth, and departed 

 thence September third. All the collecting was done in Boul- 

 der County, and the greater part of it within a radius of five 

 miles from the city of Boulder. I collected altogether about 

 1,036 species of flowering plants and ferns. The vernal plants, 

 of course, had blossomed before my arrival, but except for 

 these the flora of Boulder is fairly well shown in the collection. 



In the list of plants here given there have been included 

 all that are known to occur in Boulder County; but inasmuch 

 as the boundary between Grand and Boulder Counties lies 

 along the summits of the main range of mountains it is impos- 

 sible often to tell in what county a given plant has been col- 

 lected. Similarly Long's Peak lies partly in Larimer County 

 and partly in Boulder County. In all cases in which plants 

 have been cited from a mountain lying partly in Boulder Coun- 

 ty, these have been included in the list, unless a definite locali- 

 ty in the other county is given. Plants admitted to the list 

 because of the citations given in Rydberg's Flora of Colorado 



