Development of the Vegetation of New York State 41 
product of its environment. The former expression is true, 
the latter not necessarily so, if, for example, we should say 
that the vegetation of New York State is a product of the 
New York State environment. If we have read the geo- 
logical record correctly, the floristic elements which 
we have in New York as well as the growth forms 
and the plant societies were largely products of en- 
vironmental forces operating long before the post-glacial 
conditions of environment in our State became operative. 
We must recall also that the glacial invasions obliterated 
our vegetation, though we must suppose that many of its 
pre-glacial and inter-glacial floral elements, if they were 
not already represented south of the ice-covered region, were 
caused to migrate southward and so stood in a relation to 
permit reinvasion upon the retreat of the ice cap. So we 
ean scarcely say that this environment moulded a vegetation 
product but rather that the already largely determined 
elements of a vegetation fell into their respective environ- 
mental relations. This statement in no wise affects the view 
as to what réle environment, wherever operative, plays in 
determining the evolution of floral groups or the origin of 
growth forms and the development of plant societies, while 
on the other hand, it enables us to emphasize again the fact 
that environmental experience has become so thoroughly 
impressed on species that one is struck rather by their habit 
of falling into their environmental niches than by the 
tendency to get out of them. See also page 48. 
Thus after repeated migrations, or at least of extinction 
within the area of New York — caused especially by glacial 
invasions — our northern conifers, which we saw were 
segregated in boreal regions with the gradual differentiation 
of polar climate, have each time fallen back into the same 
zonal relation. 
The State of New York presents an environment of signifi- 
cance in determining the segregation of vegetation upon it in 
the following respects: 
1. By reason of its geographical position, especially as to 
latitude, the State lies within the zone of great summer- 
