274 Plant Life and Evolution 



posed of pines, firs, redwoods, cedars, etc. The de- 

 ciduous trees, like the oaks and maples, form, as 

 the rule, only the undergrowth for the much taller 

 conifers, except along the streams, and sometimes 

 in the mountain canyons, where often the growth 

 is mainly of deciduous trees. Many of the angio- 

 spermous trees, however, are also evergreens, like 

 the live-oaks, tanbark-oaks, madrono, and laurels, 

 and a very characteristic feature of the drier forma- 

 tions in California is the dense scrub, or " chap- 

 arral," composed of a great variety of shrubs, most 

 of them evergreens, like the manzanita and toyon, 

 but with some deciduous species like the buckeye 

 and poison-oak. 



The Flora of California. California illustrates 

 very perfectly how important a part topography 

 plays in the origin of a flora. The Sierra 

 Nevada and Coast Ranges form perfect high- 

 ways for the migration of northern plants, which 

 follow the mountains southward, ascending as they 

 go to the altitude best fitted for them. In the 

 cool moist forests of the outer Coast Range the 

 northern types are especially at home, and many 

 of the common flowers, violets, trilliums, spring- 

 beauties, dog-tooth-violets, Solomon's seal, etc., are 

 closely related to species that are common in the 

 Eastern and Northern United States. With these 

 are a few forms like the fritillaries and western 

 skunk-cabbage, and the Sitka-spruce, which seem 

 to be immigrants from the Old World, via Alaska. 



