36 Proceedings of the Columbus Horticultural Society. 



Flora as it is, and have been influenced in the work by what 

 appear to have been the general conditions of plant distribu- 

 tion on our continent. If the method of study be correct, 

 then any errors in the detailed lists will certainly be corrected. 

 Such errors and especially omissions will doubtless present 

 themselves to many. 



The discussion of the geology and topography of Ohio is 

 largely excluded, and we may only refer to some very general 

 features.* The western half, exclusive of a limited area in 

 the extreme northwest, is underlaid by various limestone 

 formations with accompanying shales from the Lower 

 Silurian to the Devonian in age ; bordering this on the north- 

 west and extending on the east almost through the state, are 

 the shale deposits of Devonian age ; on these in turn are 

 superposed the subcarboniferous and the coal bearing strata ; 

 the latter characterize much of eastern Ohio. The Ohio river 

 and its tributaries drain the larger part of the area, while the 

 minor drainage is by the Maumee and various smaller streams 

 into Lake Erie. The areas of former glacial activity have 

 already been indicated. 



Out of all the past changes within our boundary comes the 

 Ohio of botanical study, and we shall expect to perceive 

 marks of past conditions upon every side. The state may 

 apparently be divided into the four plant regions which follow. 

 Geological and climatic conditions appear for the most part to 

 have been potent factors ; topography is certainly not wanting 

 in influence. No part of our area is deficient in rainfall ; 

 many situations exhibit plants adapted to periods of dryness. 



L The Regio7i of Hills — Neo-Appalachia7i. 



This region includes the unglaciated south-southeastern 

 portion of the state as well as the glaciated hills along the 

 Ohio river in the southwest. The entire region is much broken 

 and broadly speaking is the Ohio Valley Hill Region, limited 

 at the northeast by the glacial advance. 



2. The Northeastern Highland Region — Neo-Transition. 



The region thus named is glaciated, often dotted by small 

 lakes, and has, for its almost median line, the Lake Erie water- 

 shed. It extends westward to the Huron river and follows the 

 Huron shale southward till this is approached by the glacial 

 moraine in northern Fairfield County ; thence to Pennsylvania 



*The reader who would pursue the matter further is referred to the Reports of the 

 Ohio Geological Survey, especially to Vol. VII, 1893, which contains a small geological 

 map of Ohio. 



