PREFACE 



The Yosemite National Park is perhaps the most delightful 

 region in all the world for the study of plant life. The wide 

 variety of conditions here found, ranging from the hot and desic- 

 cated slopes of the brush-clad foothills to the cold, bleak summits 

 above timber-line, the abode of glaciers and perpetual snow, gives 

 to the iiora an exceedingly diverse and interesting character. 

 Innumerable springs, creeks, rivers, ponds, and lakes provide 

 suitable habitats for moisture-loving plants. Rocky outcrop- 

 pings, enormous cliffs, and gravelly ridges accommodate species 

 adapted to such situations. The irregular topography yields 

 southward facing slopes which receive the full effect of the sun's 

 rays, as well as northzvard slopes where the sun's rays are little 

 felt, where it is therefore cool, moist, and shady. The altitude 

 ranges from two thousand five hundred feet in the foothill belt 

 to thirteen thousand and ninety feet along the crest of the Sierra 

 Nevada. All of these factors conspire to produce a remarkably 

 varied and interesting vegetation. 



The richness of this flora is indicated by the nine hundred and 

 fifty-five species and varieties here described. The total number 

 represented in the Yosemite National Park is considerably 

 greater, since the grasses, sedges, and rushes are here omitted. 

 Including an estimate for these, it is safe to assume that the 

 number of species and varieties of flowering plants and ferns to 

 be found within the one thousand one hundred and twenty-four 

 square miles of the park is not less than about one thousand 

 tivo hundred. 



In preparing a pioneer flora for a district like the Yosemite, 

 many corners of which have not yet been botanically explored, 

 it is manifestly impossible to avoid the omission of some species. 

 The authors have made use of every available source of infor- 

 mation and have themselves botanized over much of the Park. 

 It is therefore improbable that the list will be greatly extended 

 except for the addition of foothill species, which will doubtless 

 be found creeping up along our lower borders, especially in the 

 vicinity of Wawona and Hetch Hetchy valleys, and for the 

 addition of boreal species, the ranges of which will be extended 

 southzvard at high altitudes. Information in regard to additions 

 will be welcomed, particularly when accompanied by well pre- 



