BOT— Vol. I.] EASTWOOD— STUDIES FROM THE HERBARIUM. 8 1 



IV.— THE MANZANITAS OF MT. TAMALPAIS. 



Across the Golden Gate from San Francisco lie the 

 picturesque hills of Marin County. These reach their 

 highest point on Mt. Tamalpais, which rises to an altitude 

 of 2604 feet. The rocky slopes of this interesting moun- 

 tain are densely clothed with a shrubby vegetation, except 

 in some spots where a bluish gray volcanic rock becomes 

 exposed. The chief shrubs are Pickeringia montana, Erio- 

 dictyon glutinosum, Castanopsis chrysophylla, Adenostoma 

 fasciculata^ several species of .^uerciis and Ceanothus, Um- 

 bellularia Califoi'nica, Vaccinium ovatiim, and the different 

 kinds of Arctostaphylos or Manzanita. 



Of these manzanitas, there are at least four forms that 

 appear quite different from each other; but the amount of 

 variation is so great among some of them, and with one 

 exception they are so different from all forms definitely 

 described, that their identification is a puzzle that has been 

 engaging the attention of the writer for more than a year 

 on frequent trips to the mountain, at all seasons and over 

 its many trails. If the manzanitas in other sections of Cali- 

 fornia present as many variations as these on Mt. Tamal- 

 pais, it will be many years before the genus Arctostaphylos 

 is understood, and then, probably, the results will be secured 

 only through systematic cultivation of the various forms in 

 Botanic Gardens. A beginning is already made in the 

 Botanic Garden of the University of California, where 

 several species are now growing. 



The inadequacy of printed descriptions and the impos- 

 sibility of deciding, without the types for comparison, to 

 which species some of the Mt. Tamalpais forms are most 

 closely allied, makes it seem necessary to describe and name 

 each form, that seems undescribed, as a distinct species, 

 leaving to the future monographer of the genus the task of 

 assigning definite limits, if that be possible in so polymor- 

 phous a genus, which continually suggests hybridization or 

 a very active and unlimited tendency to vary. 



