The territory to which this book applies extends 

 from Sonoma to Santa Clara, and from Niles to 

 the Pacific Ocean. 



Since the year 1884, when the Synopsis of Genera 

 was published, there have been added several 

 genera, which up to that time had escaped obser- 

 vation. Continued investigations will lead perhaps 

 to the discovery of some more; certainly, they will 

 lead to the addition of species hitherto unobserved 

 in the territory. I have followed as much as pos- 

 sible the admirable work of Asa Gray and Sereno 

 Watson " Botany of California/' and from their 

 views I have deviated only when opportunities 

 for studying the plants from specimens growing on 

 the spot afforded to me. ample grounds for a view 

 differing from that expressed by recognized au- 

 thorities. 



As to many of the species characterized in this 

 book, there exists still a considerable degree of 

 uncertainty. Many of our Californian species split 

 into numerous variations, which mingle frequently 

 with variations of related, equally variable species. 

 Some of these variations owe their existence to hy- 

 bridization; and this circumstance is probably the 

 reason why several species described and charac- 

 terized by different authors have not been found 



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