THE BROAD-SCLEROPHYLL VEGETATION OF CALIFORNIA. 13 



Over the great area of the Great Basin and the Rocky Mountains 

 covered by the lightest shading, the distribution of the few broad- 

 sclerophylls is of course not continuous. The extreme limits of 

 the ranges are indicated, detailed mapping in these cases being 

 impossible. 



Focusing attention upon the State of California, the following 

 facts appear : First of all, it is seen that the Coast Ranges, the lower 

 and middle altitudes of the Sierras, and the coastal area of southern 

 California are the regions where the broad-sclerophylls are of im- 

 portance. In two places they are absent — the Great Valley and 

 the alpine regions of the Sierras. Over much of the former occasional 

 plants of a number of species occur, and the region might fairly 

 be covered by the lightest shading. This problem is discussed 

 later (p. 77). 



The development of the type in the Sierras is moderate, the belt 

 of maximum number being in the region where the ranges of foothill 

 and forest species overlap. 



The zone of deep shading in the Coast Ranges, southward through 

 southern California into Lower California, is the outstanding feature. 

 Northward this follows the inner ranges, but from Monterey Bay 

 south it borders the coast. Two spots of very special abundance 

 are seen, one extending from Marin County to the Santa Lucias, 

 the other covering the mountains of Santa Barbara and Ventura 

 Counties and the San Gabriel and San Bernardino Ranges. Too 

 much reliance should not be placed upon these, since both regions 

 have been explored and studied with comparative thoroughness. 

 It is true, however, that certain portions of these areas have been 

 proved to be rich in endemics, and it may well be, therefore, that 

 the seeming abundance of species in these spots is not wholly a false 

 appearance. 



A division into regions, with lists of species confined to each, will 

 supplement the data furnished by the map: 



In the Sierra Nevada 32 species occur, but 15 of these are found 

 also in all the other regions and only the 3 following are confined 

 to this region alone: 



Ceanothus diversifolius. Ceanothus parvifolius. Arctostaphylos mariposa. 



In the North Coast Ranges (San Francisco Bay being the point 

 of division), 38 species occur, and 1 is endemic, Arctostaphylos 

 stanfordiana. 1 



In the South Coast Ranges 37 species occur, and the 6 following 

 are endemic: 



Ceanothus dentatus. Arctostaphylos andersonii. Arctostaphylos pumila. 2 



papillosus. 2 hookeri. 2 vestita. 2 



1 Here, and in other lists, several species might be added if accurate knowledge concerning 

 their validity and range could be obtained. 



2 Members of the group of endemics characteristic of the Monterey region, A. hookeri and 

 A. vestita being strictly confined to it. 



