132 OUTLINE OF PLANT GEOGRAPHY 



ture from the great snow fields and glaciers which cover the 

 mountain for a distance of nearly 8,000 feet. 



The eastern slopes of the Cascades are much drier, and the 

 plateau traversed by the Columbia and its tributaries is arid, 

 and belongs rather to the Great Basin than to the Pacific Coast. 



The southern Cascades have a much less luxuriant vegeta- 

 tion than in the Puget Sound region, and this becomes very 

 marked as the California boundary is reached. The northern 

 conifers become less numerous, and the yellow and sugar pines, 

 and white fir are more in evidence, and indicate an approach 

 to the drier climate of the Sierra Nevada. 



Along the coast, however, the dense wet forest belt is con- 

 tinued into northern California, but the characteristic trees 

 of the northern forests are to a great extent replaced by the 

 redwood {Sequoia sempervirens) , which in some places forms 

 pure stands of great extent, and throughout the great redwood 

 belt, reaching from southern Oregon to central California, is 

 the predominant species. 



Associated with the redwood, throughout most of its range, 

 is the tan-bark oak (Pasania densiflora) the only American repre- 

 sentative of a genus otherwise restricted to Himalayan and Indo- 

 Malayan regions. Another beautiful tree of the redwood region, 

 but not confined to it, is the madrono (Arbutus Menziesii), with 

 broad evergreen leaves suggesting a magnolia. This reaches 

 its greatest dimensions in central California. 



Owing to the great diversity of topography and climate, Cali- 

 fornia surpasses any other equal area in the United States in the 

 richness of its flora. Not only is the number of species very great 

 but a suprisingly large number are peculiar to the state, and often 

 of very limited range. 



Covering 10 degrees of latitude (42° to 32°) and with a coast- 

 line nearty a thousand miles long there is naturally considerable 

 range of climate due to latitude; but this is very much less marked, 

 as regards temperature, than is the case on the Atlantic coast, 

 due to the uniform temperature of the Pacific. 



While the temperature in California is relatively little affected 

 by latitude, this is not true of the precipitation. Eureka, near the 

 northern end of the state has more than four times as much rain 

 as San Diego; while some stations in northwest California may have 



