312 The Ohio Naturalist. [Vol. XI, No. 6, 



THE ANCIENT VEGETATION OF OHIO AND ITS ECOLOG- 

 ICAL CONDITIONS FOR GROWTH.* 



Alfred Dachnowski. 



It is generally agreed that the life relations between plants and 

 their habitats are an outcome of certain definite processes linked 

 inseparately with the past. Whatever the possible method of 

 evolutionary advance, whether under pressure of unusual envir- 

 onmental conditions or of different inherent irreversible, limits of 

 organic variability, the behaviour of plants under analytical 

 experimental tests will continue to contribute the generalizations 

 of real interest and importance. The facts and the conditions of 

 the present alone can aid in the interpretation of the past. 



The comparatively abundant infoniiation which we possess as 

 to the present vegetation in aspect, form, structure and function 

 as related to differences in physical, chemical and biological fac- 

 tors is in striking contrast to the absence of a correlation of sim- 

 ilar data as regards environmental conditions during geological 

 periods. From the point of view of Ecology, either as geographic 

 ecology interpreting similarities and differences in vegetation 

 identifiable with factors of latitude and climate, physiographic 

 ecology constituting evidence of more local and genetic forces 

 and concomitant organic response, or physiological ecology which 

 is less floristic in aspect than either of the preceding views and 

 which offers the adequate basis of organic response from exper- 

 imental evidence of the physiological behaviour of plants tmder 

 kno\yn conditions, to one and all the vegetation conditions of the 

 past are of considerable value, whatever the method of endeavor 

 to understand the factors which the fossil plants record. Those 

 who have confined their ecological study to the environmental 

 investigations of the present must sooner or later test and supple- 

 ment their investigations by reference to the past. And the aim 

 should be to reproduce not only an accurate fragment of botanical 

 history from the study of fossils and their respective strata, but 

 to correlate stitictural characteristics with physiological condi- 

 tions of growth, appl\-ing the knowledge of relations gained from 

 living plants. Whether or not the data can be accepted as sound 

 links in the chain of evidence rests largely in the value of the 

 experimental work at hand and in the degree with which they 

 inter]3ret many apparent anomalies. 



The limiting climatic and physiographic features which 

 characterize bogs, and the structural features and functions of 

 the vegetation peculiar to them, have seemed to the writer of suf- 

 ficient interest to invite attention to an inquiry on the probable 



* Published by permission of the State Geologist. Contribution from 

 the Botanical Laboratories of Ohio State University, No. 62. 



