BIG SPRING PRAIRIE. H 



A xero-mesophytic area is one in which there is an 

 approximately even mixture of the two classes from 

 which the name is derived. The same applies to the 

 term Hydromesophytic. This enables us to more 

 clearly define the peculiar characteristics of limited 

 areas, which would otherwise be impossible. 



Furthermore these terms can be employed abso- 

 lutely or relatively. Absolutely considered there are 

 no extensive xerophytic plant societies in Ohio, as only 

 the plants occurring on more or less perpendicular rock 

 walls; on edges of cliffs, on the lower and middle 

 beaches of Lake Erie; on the nearly perpendicular 

 surfaces of freshly eroded river banks can be classed as 

 such. Even in these cases the term applies rather to 

 the hard condition of life and to the difficulty of gaining 

 or maintaining a foothold than to the idea of drought- 

 enduring as commonly understood. Relatively we can 

 designate that society of any given region, which occurs 

 under the most unfavorable conditions, relatively 

 xerophytic, and those in the wettest, hydrophytic, and 

 the gradations between them as before indicated. As 

 the latter view is apt to lead to confusion, we shall con- 

 fine ourselves to the former limitations, and according- 

 ly consider the Xero-mesophytic as the extreme of plant 

 society in the area under consideration. And even 

 under this heading, we can bring only the summits of 

 the ridges, the exposed slopes, and the evident outcrops 

 of the Niagara limestone. 



Both ridges were formerly densely wooded, but at 

 present there are only a considerable number of small 

 areas which can be termed woodlands, and even from 

 these, the largest and most desirable timber trees have 

 been removed. 



Although the ridges as a whole exhibit a character- 

 istic forest formation, yet this forest formation can be 

 divided into two distinct types occurring respect- 

 ivelv on: 



