THE NORTH TEMPERATE ZONE 141 



These cool, moist coast mountains harbor many plants ev- 

 idently of northern origin, such as violets, trilliums, lilies, anemones, 

 Erythronium, roses, elders, and many others. While these genera 

 are wide-spread boreal ones, the species are mostly peculiar. 



On the valley side of the mountains the character of the vegeta- 

 tion is very different. While redwood is still found in places, the 

 forest is mainly an open one in which oaks predominate, partly 

 the deciduous black oak (Quercus Kelloggii), partly live oaks. 

 Madrono, bay, and buckeye {Aesculus Californica), also occur, as 

 well as other trees and shrubs. 



The dry slopes are covered with chaparral made up of a variety 

 of shrubs and small trees, mostly evergreen, but including a good 

 many deciduous species. Several species of Ceanothus, with 

 white or blue flowers are abundant and very ornamental, and 

 known locally as "wild lilac." Manzanita (Arctostaphylos) is 

 also represented by several species. These two genera are remark- 

 ably developed in Pacific North America. Several species of scrub 

 oaks, buckeye, Garrya, " poison oak" (Rhus diver siloba) , "Yerba 

 santa" (Eriodictyon), Adenostoma, bush-poppy (Dendromecon), 

 several species of Ribes, as well as the more familiar roses, black- 

 berries, and elder, are common constituents of the chaparral. 



The valley itself is open, and except on the north slopes of the 

 foot-hills, is scantily wooded. Groves of picturesque, spreading 

 oaks, however, give the landscape a park-like aspect that is very 

 attractive. The commonest oaks are the live oak (Q. agrifolia) 

 and the white oak (Q. lobata). The latter under favorable condi- 

 tions reaches a gigantic size, hardly rivalled by any other species. 

 Less common in dry soil, is the blue oak (Q. Douglasii). 



In general, both the woody plants and the herbaceous vegetation 

 of the valley, are of southern rather than northern affinities, and 

 are related more or less closely to the flora of the northern Mexican 

 plateau, which really comprises southern California and Arizona. 



The coastal mountains of southern California are much drier 

 than those of the north, and except in the canyons are largely 

 bare of trees, the southern Californian forests being mainly re- 

 stricted to the higher elevations of the interior mountains. Along 

 the coast and in the interior valleys, the rainfall is scanty, and 

 much of the country is too dry for tree-growth, and some of it is 

 genuine desert. 



