3 1 2 
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 information 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 under 
known 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 structural characteristics with physiological condi- 
tions of growth, applying 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 
interpret 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. 
