Development of the Vegetation of New York State 69 
The situation was therefore essentially the migration north- 
ward of vegetation upon new terrain open to it as the glacier 
melted and the warmer zones pushed northward. Consider- 
ing that the region had been covered by vegetation of 
similar floristic stock in preglacial or interglacial times, it 
would be as previously expressed a falling back of species 
into the zonal relations which long environmental experience 
had impressed upon them. We must look upon the southern 
Appalachian region especially, but the greater southern 
deciduous forest region in general, as being the region to 
supply the floristic stock and therefore the center from which 
the northward migration proceeded. The present botanical 
status of the southern Appalachians is most instructive in 
this connection. A transect of the Appalachian range from 
the “‘ downfall” of the Piedmont Plateau over the highest 
summits in North Carolina, southwestern Virginia and 
Tennessee would include, in addition to species which do not 
reach so far north as New York, essentially the forest flora 
both of our deciduous and of our coniferous forests and more 
or less segregated into zonal relations by elevations as ours 
are by latitude, elevation, and maritime and lake factors. 
Taking the flora of this transect as a standard, a transect 
northward to and across New York shows the gradual drop- 
ping out of one species after another — or groups of species 
— until when we come to the higher Adirondacks essentially 
only boreal conifers and paper birch remain of the climax 
forest trees. (See zone E of New York.) Thus, sweet gum, 
persimmon and a few others finally drop out at the lower 
Hudson region (so far as New York is concerned) ; the oaks, 
hickories, chestnut and many other associates extend yet fur- 
ther up the valleys and into the Erie-Ontario basin; maple, 
beech, yellow and sweet birch, hemlock, pine and a few 
others upon the plateau region, dropping out finally at more 
or less 3500 feet elevation in the Adirondacks where as 
stated, spruce, balsam (Abies balsamea) and paper birch 
persist. It is interesting to observe that the forest floor 
species extend in great abundance even to the Alleghany 
