50 HARPER 



abundant than all other herbaceous vegetation combined. Cryp- 

 togams are represented only by one fern and one fungus. 



The ranges of the dry pine-barren plants are quite interesting. 

 None of them are confined to the Altamaha Grit region, or even 

 to Georgia, and not more than two-thirds are confined to the 

 coastal plain. Most of the remaining third are found in dry 

 woods and fields and on southern slopes of mountains in the 

 upper parts of the state, 1 where they are subjected to very 

 similar conditions of soil, light, and heat. Quite a number 

 range still farther north, and are inclined to become weeds in the 

 northern states. Nearly all the dry pine-barren plants grow 

 also in the adjacent Lower Oligocene region of the coastal plain, 

 but not so many descend into the flat country toward the coast. 

 Very few extend southward to the tropics, or even to sub- 

 tropical Florida ; and none of them are native in the Old World. 



The highest and driest parts of the pine-barren ridges are 

 often a little sandier than the rest, and contain a larger pro- 

 portion of oaks, and are known as "oak ridges." The flora of 

 the oak ridges, though approaching that of the sand-hills (to be 

 discussed below) scarcely merits separate recognition, and has 

 all been included in the foregoing list. 



3. Intermediate Pine-Barrens. 



Descending the slope of any of the innumerable low ridges in 

 the Altamaha Grit country we pass by imperceptible gradations 

 from dry pine-barrens into those which are perpetually moist. 

 Very few species range all the way from dry to moist pine-barrens, 

 however, and between these habitats there is always a transition 

 zone of varying width where species from both meet on common 

 ground. This transition zone, which may be designated as the 

 intermediate pine-barrens, (See Plate III, Fig. 1.) for want of a 

 better name, 2 usually contains in addition some species which are 

 rare or wanting in both adjacent zones, and these therefore entitle 

 it to be considered separately, though its boundaries are often 



iSee Bull. Torrey Club 27: 327, 328. 1900; 30: 294. 1903; Torreya, 

 S: 56. April, 1905; also Kearney, Science, II. 12: 830-842. 1900. 



2 In my previous writings I have usually referred to them as rather dry 

 pine-barrens. 



