ALTAMAHA GRIT REGION OF GEORGIA 337 



Georgia, and many of them also reach the mountains and 

 northern states. These widely distributed species are mostly 

 plants of rock outcrops, dry pine-barrens, hammocks, river- 

 swamps, and bluffs, as has already been pointed out in the 

 discussions of these habitats, and are very largely dicotyledons. 

 About 4.4% occur in the Piedmont region only in a few isolated 

 localities, mainly in sandy bogs. The remainder, about 4.6%, 

 grow in bogs and allied habitats in the glaciated region, but 

 are absent or very rare in the Piedmont region and southern 

 mountains. 1 



The above percentages may be tabulated as follows: 



Reaching inland limit in Altamaha Grit region 

 Reaching inland limit in Lower Oligocene region 



Confined to pine-barrens 

 Inland to Cretaceous and Eocene regions only 



Confined to coastal plain 



17 

 16 





60 



27 



33 

 2 7 





Common in Piedmont region 

 Only in bogs in Piedmont region 

 In glaciated region but rare in Piedmont 

 Not confined to coastal plain 



3 1 

 4.4 

 4.6 









40 



40 



Total 



100. 



100 



100 



The ranges may be correlated with arbitrary lines (parallels 

 of latitude and political botmdaries) as follows. A little more 

 than half (53%) of the species are reported to range north of 

 latitude 36 30' (and therefore into the so-called "Manual 

 region"), mostly in the coastal plain of course, some along the 

 coast, some in the Mississippi valley, and some on both sides of 

 the mountains. About 5% range both northward into the 

 Manual region and southward into the West Indies or Mexico 

 (provided the tropical species are all identical with ours), and 

 2.7% range southward into the tropics but not northward. 

 Most of the species common to the Altamaha Grit region and the 

 West Indies, 50 or 60 in all, are such as are not confined to the 

 Lafayette, a formation which is not definitely known outside 

 of our coastal plain. In the other parts of the coastal plain of 

 Georgia, where Lafayette-less areas are more common, the per- 

 centage of tropical species is doubtless greater, though I have 

 not yet collected accurate statistics of this kind for any other 

 region. Probably none of our native species reach Europe or 

 1 See Rhodora, 7 : 09-80. April, 1905. 



