64 College of Forestry 
oak and hickory and the large growth of chestnut in- 
dicate the presence of this zonal condition much as it 
prevails in the middle Hudson Valley region. 
2. The prominence of basswood and American elm 
in the wet land forest (woodlots) of the Ontario plain 
(e. g. in Niagara and Orleans counties) with the infre- 
quence or absence of conifers, especially white cedar and 
tamarack (except in bogs), contrasts with the infre- 
quence of basswood and tendency to dominance of coni- 
fers (particularly of white cedar) as noted in the St. 
Lawrence Valley and indicates an austral rather than 
boreal relation of the former. 
3. Perhaps even more convincing evidence is given of 
the moderated climatic conditions of the region lying in 
the lee of the Great Lakes in New York by the presence 
of species of more pronounced austral affinities such as 
paw-paw, hop tree, spiny aralia, American crab apple, 
hackberry, tupelo gum, flowering dogwood and redbud 
among trees or large shrubs, and lotus, swamp. rose- 
mallow, golden seal, sensitive pea, wild senna and other 
miscellaneous species. 
Apparent Effect of Glacial Filling on Zonal Relations 
Through the Creation of Bog Habitats. 
Throughout the State, generally speaking, one of the effects 
of glacial filling, i. e., the deposition of glacial debris so as 
to obstruct drainage, has been to promote bog formation by 
vegetation. In every such case there comes to be a dominance 
of so-called boreal species — black spruce, tamarack, various 
heath shrubs, sedges, orchids, sphagnum moss and so on — 
and often these bogs have been spoken of as “islands” of 
boreal life. Such bogs occur also in the region we have just 
been considering as having an austral trend of the flora by 
reason of lake influence; for example, the Mendon Ponds, 
twelve miles southeast of Rochester. We naturally suppose 
that the lake influence would be effective here, but the char- 
acter of the plant society remains as fixed as it does at 
elevated points on drainage divides of the Alleghany plateau 
