INTRODUCTION. 



THIC area drained by the Upper Susquehanna and its tribu- 

 taries forms an irregular stretch of country about two hun- 

 dred miles long and from one-third to one-quarter as wide, 

 lying along the forty-second parallel of north latitude, in the States 

 of New York and Pennsylvania. The greater part of this region 

 is in southern New York, and comprises the counties of Otsego, 

 Chenango, Cortland, Broome, Tioga, Chemung and Steuben, with 

 portions of Delaware, Madison, Schuyler and Allegany. In 

 northern Pennsylvania it includes parts of the counties of Wayne, 

 Susquehanna, Bradford and Tioga. On the north, a compara- 

 tively low ridge turns the drainage towards the lakes of central 

 New York, and on the south a higher elevation deflects the waters 

 into tributaries of the Susquehanna, which join it much beyond 

 our limits. Upon the east is the drainage system of the Delaware 

 river, and westward the great lakes and the tributaries of the Ohio 

 river receive the rainfall. The flora of this region is of much in- 

 terest, not alone from the fact that it has only been known in a 

 general way, but also because it is the connecting link between 

 the "Flora of the Lackawanna and Wyoming Valleys" and the 

 "Cayuga Flora," and thus completes a chain of Local Floras ex- 

 tending from eastern Pennsylvania to Lake Ontario. 



Topographically, this area may be divided into three sections 

 which are in a measure different from one another. In the ex- 

 treme east the surface is mountainous, with many steep acclivities, 

 whose summits rise to from fifteen hundred to two thousand feet 

 above tide. The drainage is principally southward by way of the 

 Susquehanna and Chenango rivers. The elevation gradually de- 

 creases as the central region is approached. This is occupied by 

 the broad main valley of the Susquehanna extending nearly east 

 and west, with a few short lateral valleys at nearly right angles to 

 it. At this point our region is narrowest, although the surround- 

 ing hills seldom rise to heights of more than twelve hundred feet 

 above tide. In the western section the drainage from the north, 



