58 



PLANT LIFE OF ALABAMA. 



crop can not be pushed, and which also presents n barrier to several 

 trees and a number of other plants of Southern distribution that are 

 only rarely met farther north, as, for example, the willow oak (Qiwcw 

 phellos), loblolly pine (Pinm taeda), long-leaf pine (/V////.S palttstri*), 

 and cane (Arundinaria macrospernta). This line, roughly extending 

 from the Atlantic/coast at the mouth of the Chesapeake Bay westward 

 to southwestern Missouri and northern Arkansas, w r as located by Gray 

 along latitude 36 30', and by him regarded as the line of separation 

 between the two principal floral divisions of eastern North America, 

 namely, the flora of the northern United States and Canada and the 

 flora of the Southern States. In Alabama it is only this lower belt of 

 the Carolinian area, embracing the mountain region and the lower hills 

 with which we are concerned. 



MOUNTAIN REGION. 



The extreme southern spurs of the Appalachian chains belong, with 

 their western and eastern frontiers, to two distinct members of this 

 mountain system. Their differences in topographical and stratigraph- 

 ical conditions affect visibly the distribution and localization of species 

 in the sections traversed by them. 



RANGES OF HILLS OF THE METAMORPHIC AND OLDER PALEOZOIC STRATA. 



Physioyraphwal features and climate. The spurs which enter the 

 State at its eastern boundary are the continuation of the most easterly 

 of the Alleghenian ranges, and are composed of metamorphic crystal- 

 line rocks skirted by the oldest sedimentary strata. They extend from 

 the Coosa River to the Tallapoosa and include the most elevated parts of 

 the State. The valleys reach an extreme elevation of about 1,000 feet 

 above sea level, and the highest summits of the ridges reach an alti- 

 tude of from 2,000 to 2,400 feet above the Gulf of Mexico. These 

 ridges rise abruptly from the valleys and above the lower hills; their 

 steep flanks are covered with the sharp-edged fragments of the sili- 

 ceous rocks which crown their crests with bold cliffs. 



The locality of Talladega (altitude 860 feet) coincides nearly with 

 the center of this subdivision. The records of daily meteorological 

 observations made at this town for only two successive years are at 

 hand, which are embodied in the following table: 

 Data of temperature (deywx h\) and precipitation (inches) at T<t//d<'</<i for tiro 



This mean annual precipitation can be considered as representing 

 that of the whole subdivision, with the exception of Lee County, on 

 its southern border, where it rises to 54.4 inches. 



