y8 FLORIDA GEOLOGICAL SURVEY I3TH ANNUAL REPORT 



In each region described the principal vegetation types (which 

 are discussed more fully in the general part of the report) are in- 

 dicated, and the commonest large trees (i.e., those large enough to 

 be sawn into lumber), small trees, woody vines, shrubs and herbs 

 are listed as nearly as possible in order of abundance; which besides 

 bringing out the general appearance of the vegetation also shows at 

 once each region's resources in timber and other wild products of 

 the vegetable kingdom. There are of course, all gradations between 

 trees and shrubs, and a species which is a small tree in one region 

 may be a large tree or a shrub in another, or even in different 

 habitats in the same region. But although no hard and fast lines 

 can be drawn, some sort of size grouping has to be used, for it is 

 impracticable to compare the relative abundance of plants differing 

 greatly in size, such as trees and grasses. Mosses, lichens, fungi, 

 etc.. are omitted entirely, partly because they form such an insig- 

 nificant fraction of the total bulk of vegetation, and also because 

 only a few specialists (of whom the writer is not one) can identify 

 them positively in the field. 



It (lid not seem worth while to assign percentages to nearly all the 

 species, as was done in the northern Florida report, on account of 

 the incompleteness of the data, but in the general discussion there 

 is a census of timber trees, giving within certain limits the propor- 

 tion that each is supposed to constitute of the total forest of each 

 region. And the percentage of evergreens in each region has been 

 estimated, as before, for that being made up of figures for a number 

 of species is more accurate than the percentage of any one species 

 The significance of evergreens is that, other things being equal, 

 they are most abundant on the poorest soils ; for a tree growing in 

 very poor soil has difficulty in getting enough nourishment to make 

 a complete set of leaves every year, and is almost obliged to keep 

 each leaf twO or more years (sometimes a dozen years in the case 

 of some of the spruces of the far north, where the soil is frozen 

 about half the year) ; while a tree in rich soil may take up mineral 

 matter in solution so fast that it has to have large leaves to store 

 the surplus in and shed them every year to get rid of it* 



*For additional notes on the relation of evergreens to soils see 6th Ann, 

 Rep. Fla. Geol. Surv., 175-177 (footnote); Science IT. 42:500-503. Oct. 8, 1915: 

 Bull. Geog. Soc. Phila. 16:111. Dec. 191S; Geol. Surv. Ala. Special Rep. Xo. 

 II, p. 90, 1920. 



