Harper : Coastal plain plants in Georgia o93 



or lumberman to move to Europe and continue the same occupa- 

 tion there. The tendency is always for climax vegetation to gain 

 ground and pioneer vegetation to lose,* and this tendency is coun- 

 teracted only by such forces as erosion, fire, and civilization. The 

 species discussed in this paper, or the majority of them, must 

 therefore have once been more widely distributed in the highlands 

 than they are now ; and doubtless not a few species now strictly 

 confined to the coastal plain were more or less common farther 

 inland in past epochs. 



It is not likely that all species now endemic to the coastal plain 

 have had such a history, however. The distribution and relation- 

 ships of many of them make it seem most likely that their ances- 

 tors came in by way of Florida after the coastal plain last emerged 

 from the sea, probably about the close of the Pleistocene period. 

 (The Pleistocene submergence of the greater part of the coastal 



i 



plain has been overlooked by nearly all botanists who have dis- 

 cussed the phytogeographical problems of the southeastern United 

 States, but it is pretty generally accepted by geologists, and must 

 have had a far-reaching effect upon the present composition of the 

 flora.) Many species now growing in the Piedmont region have 

 indeed near relatives in the tropics, and such (as Mr. Kearney has 

 already suggested) probably date back to the Miocene period, 

 when semi-tropical vegetation extended to Greenland. 



T 



After the last emergence of the coastal plain it doubtless 

 received plant immigrants both from the north and from the south, 

 and the present endemic coastal plain species must have been 

 derived (by mutation or otherwise) from at least two different 

 sources. Perhaps in the not distant future it will be possible to 

 separate them all into two or more classes on this basis. 



College Point, N. Y. 



*See Hull, Torrey Club 33: 529, 531, 1906; 34: 373. 1907; Southern 



Woodlands i^: 8-9. 1907. 



