OHIO BIOLOGICAL SURVEY 249 



of Pennsylvania and West Virginia as well. The descriptions here 

 given may be applied, therefore, in a general way to the whole of this 

 country, gradually becoming less and less applicable as the distance 

 from Sugar Grove increases and new elements come in to affect the 

 plant covering. This particular area is, however, better adapted to 

 serve as a type of the whole hill country than any other which could 

 be selected within the state of Ohio. The reason for this lies in the 

 greater ruggedness of the country which operates in two ways : first, 

 it is only in a country with high cliffs and deep ravines that the climax 

 associations, both mesophytic and xerophytic, which characterize this 

 territory can develop ; and second, the very roughness prevents the agri- 

 cultural utilization of the country and retards clearing so that here 

 one finds a much larger proportion of unspoiled forest than in any 

 of the country round about. 



The causes which led the writer to undertake the present work 

 were : first, interest in collecting over the region itself ; second, a belief 

 that an account of the flora would be of service to those who are study- 

 ing the geographical ranges of the plants of North America ; third, 

 a desire to present some account of its ecology which might be useful 

 to phytogeographers in general, such studies of the Alleghenian region 

 being at present rather few and far between ; and finally, a recognition 

 of the fact that the portable sawmill is devastating the forest so rap- 

 idly that only a few years hence it will be impossible to reconstruct 

 for the service of posterity a picture of the aboriginal condition of the 

 country. Indeed, some of the associations which are here described 

 have been already obliterated and it would be impossible now to dupli- 

 cate this account. 



Geology and Physiography. The physiography of the country re- 

 sembles in a general way that of the hill country found over all of 

 southeastern Ohio and much of West Virginia. It is a rolling upland 

 cut up with numerous deep ravines giving a total relief of from three 

 to four hundred feet. 



The shape and boundaries of the Sugar Grove region are deter- 

 mined, except on the north, by the area of maximum outcrop of a 

 heavy sandstone of carboniferous age, the Blackhand conglomerate, 

 which weathers out in high cliffs around every little ravine. That the 

 greatest exposures of sandstone should be limited to so small an area is 

 due principally to the stratigraphic peculiarities of the sandstone which 

 in turn are bound up with the history of its disposition. The various 



