DISTRIBUTIONAL NOTES 333 



At this point might be mentioned two shrubs (one of them 

 occasionally arborescent) whose chief distribution in Alabama is 

 in the southern red hills, though they have been seen once or twice 

 in the hill country north of the fall line, and they both range north- 

 ward to Canada; namely, Dirca pahistris and Cornus alternifolia. 

 Just why they should prefer the southern to the northern part of 

 the state is an unsolved problem, unless there are some unsus- 

 pected differences between the northern and southern forms. 

 (Compare ]\IagnoHa Frascri and M. pyratnidata.) 



Almost the only woody plants that seem to have their inland 

 limits in the black belt are Pcrsea Borbonia and Bnmclia lanugi- 

 nosa. Pinus glabra and Magnolia grandiflora extend just a little 

 farther inland, to the Eutaw belt, and the following seem to have 

 their inland limits in the more typical portions of the central pine 

 belt (6A or 6B). 



Pinus serotina 



Smilax Walteri 



Myrica cerifera 



Quercus Margaretta 



Crataegus Michauxii 



Ilex vomitoria 



Ilex coriacea 



Ilex glabra (x) 



Gaylussacia frondosa 



Viburnum semitomentosum 



Some of these may be limited by temperature, and others by 

 the scarcity of sand or swamps farther inland. 



In Alabama a large number of species that are very charac- 

 teristic of the coastal plain, and apparently confined to it in most 

 other states, are found occasionally a few miles, say ten to fifty, 

 above the fall line, in soils evidently residual from the older rocks, 

 and having no connection with the coastal plain. The reason for 

 this is not at present obvious, but there may be some unknown 

 factors of geological history involved. Among the woody plants 

 which seem to belong to this category are the following: 



Taxodium distichum 



Sabal glabra 



Smilax lanceolata 



Quercus Catesbaei 



