232 W. A. CANNON 



and in fact does so to so good purpose that a redwood grove in 

 time of fog is as damp as a tropical forest. Water condenses on 

 the leaves and twigs and drops from the branches incessantly, 

 wetting the ground beneath. Moreover, the fogs operate in an 

 indirect manner favoring the conservation of moisture by lowering 

 the evaporation rate during the dry season. Contributory evi- 

 dence that the fogs are of direct necessity is to be found in the 

 southern limits of the species. The southernmost extensive 

 growth of the redwood is in the Big Basin region. It is wholly 

 lacking at Monterey and reappears again only in seaward facing 

 valleys beginning near Carmel. The rainfall in the Big Basin 

 averages 55 inches, that at Monterey about 16 inches. To the 

 south of Carmel, gulches protected by their position from drying 

 summer winds, are often filled with heavy fogs. In spite of the 

 low rainfall here, the redwood is again found, either on the valley 

 floors or on the southern side, with northern aspect, in moderate 

 amount. 



The arboreal species of the interior, especially of the foothills 

 and the valleys, show also interesting adjustments to the environ- 

 mental conditions under which they are placed. I refer more 

 especially to the oaks which constitute a very important feature 

 of the Californian forest flora. Three species only will be men- 

 tioned in this connection, namely, Quercus agrifolia, Q. douglasii, 

 and Q. lobata, The first and last named species constitute the 

 bulk of the forests of the coast valleys, while the Douglas oak 

 frequents the foothills. Quercus agrifolia, the Coast Live Oak, 

 retains its leaves until they are replaced by new ones each spring, 

 but the other species mentioned shed theirs with the approach of 

 the winter season. 



The oaks in the valleys, as is well known, are widely scattered, 

 forming a very open stand. This recalls at once the analogous 

 condition to be seen in more arid regions where the shrubs are 

 isolated the one from the other. In the last instance it has been 

 learned that the root-systems of such species are widely extended 

 and usually reach from one individual to another so that competi- 

 tion among them for soil moisture can, and probably does exist. 



The distribution, therefore, is but an outward expression of the 



