ALTAMAHA GRIT REGION OF GEORGIA 327 



barren ponds. Euphorbiaceae, like Leguminosae, are most 

 numerous and. prominent in dry pine-barrens and on sand-hills. 



Largest genera. The twenty-one largest genera in the Altamaha 

 Grit region seem to be Rhynchospora, with 27 species; Car ex, 

 with 17 ; Quercus, 14; Panicum, 14; Xyris, 11 ; Polygala, 11 ; Lud- 

 wigia, 10; Eupatorium, 10; Juncus, 10 • Gerardia, 8; Asclepias, 8; 

 Sabbatia, 8; Scleria, 8; Eleocharis, 8; Hypericum, 7; Andropogon, 

 7; Jfefc, 7; Cyperus, 7; Laciniaria, 6; Rhexia, 6; Pinus, 6. 



The relations of these 21 genera to the 19 typical habitats are 

 shown in the following table. The names of the genera are 

 arranged systematically, each followed by the number of species 

 just mentioned. Under each habitat is the number of species 

 of each of these genera which it contains. 



Pinus is represented in all the habitats, Ilex in all but three, 

 and Rhynchospora in all but six. No Quercus ever associates with 

 a Juncus or Eleocharis in our territory. Xyris is represented in 

 every group in which Quercus is not, and associates with Quercus 

 in only one. 



Quercus would seem to be essentially an old and mesophytic 

 genus. It does not occur in any habitat with over 35% of 

 monocotyledons, but it does occur in all that have less than 20%. 

 The proportion of monocotyledons in the nine groups in which it 

 does occur is about 20%, and in the remaining ten, 37%. These 

 figures would be just about reversed for Juncus and Xyris, and 

 still more so for Eleocharis. 



Sabbatia, Ludwigia, Rhexia, and Hypericum, characteristic 

 dicotyledonous coastal plain genera, show a marked liking for 

 the society of monocotyledons, while Carex, Cyperus, and Pani- 

 cum, cosmopolitan monocotyledonous genera, lean a little the 

 other way. 



Commonest species. The 45 commonest species in the region, 

 grouped according to size, and arranged as nearly as possible 

 according to relative frequence in each group, are about as 

 follows. (The left-hand columns are to be read first.) 



TREES. 



Pinus palustris Pinus Elliottii 



Quercus Catesbaei Magnolia glauca 



Nyssa biflora Taxodium imbricarium 



