VEGETATION AND ENVIRONMENT IN CALIFORNIA 237 



stances of the relation of the roots of several species of trees to 

 the soil conditions were cited as examples. 



Naturally, no attempt has been made to trace a causal rela- 

 tion between any special response and the environment, which is 

 beyond the scope of this paper. It may be pointed out, however, 

 that often the relation is apparently more accidental than other- 

 wise. For example, the Big Tree represents, as is well known, a 

 survival from earlier geologic times when its forebears had a 

 circumpolar distribution. In such an instance the present day 

 climate evidently closely resembles the climate to which the 

 species was accustomed in those far away epochs. In another 

 manner, however, the relation of climate and of plant may be 

 more significant as leading to diversity of floral types. In brief 

 it is this: Much variation is known to occur among the individuals 

 of a collection of any species. Should the changing individuals 

 be so situated that their environment is peculiar, survival of the 

 type might take place, and the abundance of the new type would 

 depend on several things which need not be discussed here. But 

 the main point is that it would be the fortunate diversity in the 

 environment which would make this possible, and this environ- 

 mental diversity, as has been repeatedly stated, is precisely the 

 crux of the situation, the single feature which looms big among 

 those which occasion floral diversitv in the state. 



