ALTAMAHA GRIT REGION OF GEORGIA 41 



in doubt come at the foot. Such species as have been noted 

 but once or twice in any particular habitat are usually 

 ■omitted pending investigation. A species which really belongs 

 in a certain habitat should be observed there repeatedly. Rare 

 plants are not without significance to the phytogeographer, 

 but caution should be used in attempting to draw any conclu- 

 sions from them. 



We are now ready to consider the several habitat-groups in- 

 dividually and in detail. It is not possible to arrange these groups, 

 any more than taxonomic groups, in a space of a single dimension 

 (a linear sequence) and still have each immediately adjoining its 

 nearest relatives. A space of two dimensions would be better, 

 and three dimensions would probably be ideal. A diagram at 

 the end of the detailed discussion shows the relations of the 

 various groups in two dimensions, as accurately as present 

 knowledge will permit. 



Species which are believed not to be indigenous are carefully 

 •excluded from the habitat lists, and brought together in a single 

 list at the end of the ecological treatment, under the head of 

 weeds. 



THE HABITAT-GROUPS. 

 i. Rock Outcrops. 



We may appropriately begin with the hillside outcrops of the 

 Altamaha Grit itself. The nature of these has already been dis- 

 cussed, and the accompanying illustrations (Plate I, Figs. 1-2) will 

 give a still clearer idea of their appearance. As already stated, 

 they are quite rare. Their aggregate area probably does not ex- 

 ceed one square mile. The rocks and their surroundings are 

 usually dry, except around their edges or in flat places, where 

 water sometimes collects for a time in wet weather. In the 

 absence of the surrounding pine-barren vegetation they would 

 look very much like some of the granite outcrops in Middle 

 Georgia, except in color. 



The plants in the following list have been observed in the 

 counties of Tattnall, Dodge, Wilcox, and Dooly, principally the 

 first mentioned. Although they are arranged as nearly as pos- 

 sible in order of abundance, according to the system above 



