268 THE PLANT WORLD. 



Mitcliclla rcpcns L., Aster Caniptosorus Small, Smilax pumila Walt., 

 Tipiilaria discolor Nutt, SoUdago caesia L., Epiphegus Virginiana (L.) 

 Bart., Heuclicra Americana L., Uniola laxa (L.) BSP., Arisaema Dra- 

 coiitiiim (L.) Schott, JJ'oodsia obtitsa (Spreng.) Torn 



In the ravines there were very Hinited areas of rock outcrops 

 and of stream-beds, but these were so small that their flora is 

 not worth mentioning here. , 



If now we examine the characteristics of the three habitat- 

 groups above defined and of their components we shall find 

 some interesting relations between them. 



Taking first the total ranges of all the species in each group, 

 we find that nearly all of those growing on the summits 

 are common inhabitants of the pine-barrens and other parts 

 of the coastal plain ; and a few of them are so nearly confined 

 to the coastal plain that I had never seen them outside of it be- 

 fore. The plants on the dry slopes can also nearly all be found 

 in some part of the coastal plain, either in dry pine-barrens or 

 in dry woods in the Eocene region farther inland, but the ma- 

 jority of them are likewise common throughout the Piedmont 

 region of the southeastern states (at the extreme southwestern 

 edge of which Bald Knob is situated) as well as on the southern 

 slopes of the Blue Ridge. Few of the species growing in ra- 

 vines are pine-barren plants, though nearly all of them occur 

 locally in hammocks or on bluft's in some parts of the coastal 

 plain. With few exceptions they have a pretty wide distribution 

 in the Alleghanies and Piedmont region, and several of them 

 range as far north as Canada. 



Looking at the vegetation of Bald Knob from the standpoint 

 of historical development, it is pretty evident that as the hill 

 is gradually lowered by erosion, and at the same time humus 

 accumulates on the slopes, the summit flora must be gradually 

 giving place to that now inhabiting the dry slopes, and the latter 

 to that of the ravines, thus furnishing an excellent example of 

 natural succession. The same reasoning, in connection with 

 the discussion of ranges above, strengthens the evidence already 

 gathered from other sources that the vegetation of the pine- 

 barrens represents a pioneer or transient type, while that of 



