ALTAMAHA GRIT REGION OF GEORGIA 117 



For pollination about 21 species have anemophilous flowers, 

 22 white, and 10 yellow. Other colors are less frequent. It is 

 surprising how little is known about the dissemination of even 

 the worst of these weeds, and it is a mystery how the eight com- 

 monest ones above mentioned have spread over so much territory. 

 About eight species in the whole list have wind-borne seeds, 

 seven adhesive, and five fleshy fruits. 



The enumeration of weeds naturally leads to a discussion of 

 other 



Effects of Civilization. 



Most of the descriptions in the foregoing pages, up to the begin- 

 ning of the weed list, would have been equally true a hundred or 

 even a thousand years ago. But civilized man now apparently 

 threatens the ultimate destruction of all vegetation, and even in 

 a thinly settled country like the wire-grass region of Georgia 

 the effects of civilization are far-reaching and cannot well be 

 ignored. 



The greatest damage to native vegetation, amounting in most 

 cases to total destruction, is of course caused by clearing the land 

 for cultivation or for buildings. In the Altamaha Grit region at 

 present probably not over 5% of the total area has suffered 

 in this way. This is in marked contrast with Middle Georgia 

 and the Cretaceous and Eocene regions of South Georgia, where 

 the population is much denser and nearly all the land which is 

 not too steep or too wet or too rocky has already been cleared 

 and cultivated at some time or other. 



The next greatest injury is done by lumbermen in removing 

 the pine trees (lumbering in this region being almost exclusively 

 confined to pine). A pine-barren area which has been cut over 

 with the present wasteful methods presents a desolate appearance 

 for years afterward. (Plate XVII, Fig. 2.) But fortunately this 

 has little effect on the shrubs and herbs, for the amount of light 

 which they receive is not appreciably increased by removing the 

 trees, and there is never any such succession of different vegetation 

 after lumbering as is the rule in the denser forests farther inland. 



The turpentine operators do about as much damage as the 

 lumbermen. Probably nine-tenths of the specimens of Pinus 



