﻿THE FERN BULLETIN 



Vol. XVII JULY, 1909 No. 3 



THE FERN FLORA OF PENNSYLVANIA. 



BY W A. POYSER. 



The Keystone State is in shape a parallelogram, ly- 

 ing almost entirely between 42° and 39° 43' 26" north 

 V latitude, and between the irregular W-shaped Dela- 

 ware river and 80° 31' 36" west longitude. It is 

 about 160 miles long from east to west, giving an 

 area of 45,215 square miles. In the northwestern cor- 

 ner a triangular section extends to 42° 15' north, 

 forming part of the western boundary of New York, 

 and giving Pennsylvania about 45 miles of coast on 

 Lake Erie. 



The Appalachian system of mountains crosses the 

 State from northeast to southwest. It here attains its 

 greatest breadth, but none of the ridges reaches any 

 great altitude, though a few peaks among the Alle- 

 ghenies attain a height of more than 2,500 feet. The 

 surface of the State is naturally divided into three 

 sections, the low district southeast of the mountains, 

 the mountainous region, and the broken hilly plateau 

 in the west. The triangular southeastern section con- 

 sists of a narrow level plain near the Delaware, with an 

 elevation of not more than a hundred feet above the 

 sea, merging into a higher rolling region which ex- 

 tends to the base of the mountains. 



The Delaware river with its tributaries the Schuyl- 

 kill and the Lehigh drain the eastern portion. The 

 Susquehanna and its branches occupy the central area, 



