Development of the Vegetation of New York State 185 
area we are concerned with, seeing in it a more or less defin- 
itely organized mass movement of associated living plants, 
whose momentum and efficiency in occupying and transform- 
ing the land are qualities that the vegetation as a whole has 
come to possess through ages of environmental experience, 
not the least item of this experience being the contact of 
plants with each other and the mutual relations growing out 
of this contact and competition. Thus viewing vegetation, 
the developmental history which has in a measure been here 
portrayed becomes a vivid field of action in which one may 
discern the qualities and aptitudes — the special genius as 
we have before said — of our native vegetation. 
You will recall that this historical review carried us back 
into geological time when we could discern the dawn of mod- 
ern aspects of plant life, from which in a later period we 
could follow the elaboration of the wealth of species, the di- 
versity of adaptation forms and the segregation of floristic 
zones and vegetation aspects which characterize the earth’s 
vegetation of to-day with its dominant group of angiosperms 
— perhaps one might venture to say the dominance due to 
the efticiency of floral structures. We saw the vegetation 
obliterated from this area by glacial invasions, and especially 
taking the last glacial retreat as a landmark on the one hand, 
we were able to judge as to the completeness with which vege- 
tation had covered the glacially prepared terrain, and what 
effects had been wrought upon the land by the beginning of 
the present period of human occupancy. We could see in 
the return of vegetation to the glacially denuded terrain, not 
only a mass migration in which species at last settle down 
into their larger zonal or climatic relations, but even more 
important for us, we could follow, as to-day we can follow, 
the sequence of events as vegetation invades each aspect of the 
substratum and through a succession of vegetation types — 
as aquatic, marsh, marsh-meadow, swamp forest associations 
comes at length to a stage of relatively stable equilibrium, 
i. e., a climax society which in this climate is forest. 
