204 FLORIDA GEOLOGICAL SURVEY-13TH ANNUAL REPORT

from railroads, but the boundary between them and the pine forests is said to be pretty sharp, and they are said to have some pretty fertile spots, and more abundant animal life (both wild and domesticated) than most of our prairies.
 This type of prairie is subject to fire practically every year, like the flatwoods. Its chief economic importance is as pasturage for vast herds of cattle.

 SHRUBBY VEGETATION
 Saw-panetto thickets (fig. 33). The outer dunes of the east coast in the latitude of Melbourne are covered with an almost impenetrable growth of saw-palmetto about waist-high, with perhaps % of other shrubs* of about the same height, principally a small oak, Quercus miyrtifolia. The palmetto leaves in such situations, instead of being yellowish green as in the interior of the State, are covered with a thin gray waxy coating, making a strong contrast with the bright green oak leaves. (This color phase of the palmetto is common within a few miles of the coast, the green type gradually replacing it farther inland, without any apparent intergradation.) Just why trees are absent there is not certain, but the strong wind probably has something to do with it. Fire must be a rare occurrence; and neither the vegetation nor the soil on which it grows seems to be utilized for anything at present.
 Some of the treeless areas described on the preceding page might be classed as palmetto thickets instead of prairies, where the growth of palmetto is dense, but the other species associated with it would of course be mostly different from those on the dunes.
 Scrub thickets. This term is used to cover various thickets of shrubs no higher than a man's head, widely scattered over our area, but usually of very limited extent. Those on the peninsulas of Lake Tsala Apopka were described and figured in the Seventh Annual Report (pp. 141-142, 155). Other thickets that may come under this head are found near the mouth of the beautiful Pithlachascootee River in Pasco County. Wherever typical scrub (described farther on) occurs there may be areas in it devoid of trees,

 *The palmetto is not a shrub, strictly speaking, but its stiff evergreen leaves occupy about the same position that the branches of ordinary shrubs do.