CALIFORNIA FOREST FLORA 495 



mento. The valley to the south is known as the San Joaquin 

 within which the river of that name receives the waters of many 

 small streams. Jepson calls attention to the fact that the north 

 coast ranges differ in a marked degree from the south coast 

 ranges. The former are marked by the development of the red- 

 wood belt, the tan oak and Douglas fir. These forest tree species 

 are some of the marked features of this region. This region, 

 too, has a large rainfall. Jepson gives the normal seasonal rain- 

 fall as 45.59 inches with the highest recorded temperature as 

 84° above freezing and the lowest as 20° above freezing. These 

 data are for Eureka. In the southwest ranges, the region lying 

 below San Francisco is characterized by long, dry, rainless 

 summers and a low rainfall. In the Santa Cruz mountains fac- 

 ing the ocean an abundance of redwood, tan oak, sycamore, 

 Douglas fir, madrona and maple grows. The Monterey bay 

 region contains an interesting peninsula with a number of 

 conifers of restricted ranges. Jepson terms the region an 

 "aboreal island." Here are found the Monterey pine (Pinus 

 radiata), Bishop's Pine (Pinus muricata), Monterey cypress 

 (Cupressus macrocarpa) and the Gowen cypress (Cupressus 

 goveniana) . In the moister valleys of the coast range near Los 

 Angeles such deciduous trees as the large leaved maple, syca- 

 more, alder, maul oak and Douglas fir occur. 



In the San Diego district the valleys contain the cottonwood 



(Populus Fremontii) , the arroyo willow (Salix lasiolepis) and 



• the black willow (Salix nigra). On the coast north of San Diego 



about twenty-six miles, at a point known as the Torrey pine 



hill, is the Torrey pine, of very restricted distribution. 



The forest province designated as the Sierra Nevada includes 

 the area in eastern California from the base of the San Joaquin 

 and Sacramento valleys and the east slope of the range. The 

 Lake Tahoe district and the low foothills approaching the Feather 

 river divide belong to this area. The annual rainfall in the 

 foothills is low and the tree vegetation is small. The most char- 

 acteristic tree at the mouth of the Feather river canyon is the 

 digger pine (Pinus sabiniama) which is associated with the blue 

 oak (Quercns Douglasii). This is followed further by the belt 

 of yellow pine (Pinus ponderosa) and incense cedar (Liboccdrus 

 decurrens). Then come the Jeffrey Pine (Pinus ponderosa, 

 var. Jeffreyi) and the Silver Pine (Pinus mo nt kola) . Profes- 

 sor Jepson gives the precipitation in inches for Blue canyon for 



