198 Journal op the Mitchell Society [March 



mon trees, as, for example, Qucrcus phellos is credited to the valley of the Swan- 

 nanoa River, when the species should be Q. imhricaria. 



(13) Phytogeography of North America, 1911. 



(14) Plant Geography. 



(15) Coville, Formation of Leaf Mould, An. Rept. Smiths. Inst., 338-340. 

 1913. 



(16) Harshberger, Bot. Gaz. 36:375. 1903. 



(17) Kearney (1. c, 831) regards beech as being characteristically a tran- 

 sitional or northern tree. He apparently overlooked the fact that beech reaches 

 its best development along the bluff formation in Louisiana and Mississippi, and 

 that there are magnificent forests which contain a large proportion of this tree 

 throughout other portions of the Gulf States and Tennessee. It occurs to the 

 very coast in North Carolina (var. caroJiniana) and forms nearly pure stands 

 on the beech flats around the southern edge of the Dismal Swamp. Stone (Plants 

 So. N. J., p. 84, 1911) records beech as forming pure stands in New Jersey. It is 

 probable that the New Jersey tree is the same as the North Carolina coastal form. 



(18) The tendency is for southern tyjjes especially those of the low-lands 

 to extend up the valleys of the streams beyond the general limits of the life 

 zone of which they are representative as finger-like projections into the more 

 northern types when deficiency in insolation is not a controlling factor. This is 

 particularly noticeable when the soils of the lowlands are sandy and consequently 

 * ' warm, ' ' while those of the surrounding uplands are clayey and ' ' cold. ' ' Such 

 projecting tentacles of southern types are noticeable in Tishomingo County, 

 Mississippi, on the sandy alluvials of Bear Creek where typical lower austral 

 societies, such as tupelo, cypress, button bush, white bay, southern red maple and 

 alder occur contiguous to the yellow j^oplar, white oak, black oak, white hickory, 

 big leaf cucumber society on the adjacent slopes of the Pearson hills which are 

 the southwestern outlyers of the Appalachians. Similarly the intrusion of fingers 

 of the Carolinian alluvial flora into the transitional are noticeable in eastern 

 Tennessee and western North Carolina. On the other hand, when deficient inso- 

 lation is a controlling factor tentacles of northern types penetrate areas in which 

 southern types prevail. Such cases are the colonies of hemlock and birch which 

 occupy the deep gorges of the Sipsey and other rivers in Jasper County^ Alabama 

 (see also Appendix No. 8), or the groups of these trees on steep north slopes 

 along the south bank of the Potomac River below Great Falls, Virginia. 



Forest Service, 

 "Washington, D. C. 



