CHAPTER V. 
LIFE ZONES. 
By 
Cc. D. HOWE, Ph.D. 
In approaching Toronto from the United States 
either by the way of Buffalo or Detroit, one finds 
himself, immediately upon crossing the international 
boundary, in the Carolinian Area of the Upper Aus- 
tral Zone of Merriam. The northern boundary of 
this area may be approximately made by drawing a 
line from the mouth of the St. Clair River through 
London to Hamilton, and thence along the lake shore 
to Toronto. Both the mean annual temperature and 
the average temperature of the four growing months 
are slightly higher than the average for the southern 
portion of the province. ‘The rainfall is somewhat 
greater and the snowfall is considerably less than the 
average for the province. 
The milder climate of the southwestern portion 
of Ontario has resulted in the projection of the flora 
of the lowland portions of the Southern States into 
Canada, as is disclosed by the presence of such trees 
as: the tulip-tree (Liriodendron tulipifera) ; chest- 
nut (Castanea dentata); black walnut (Juglans 
migra); sour gum (Nyssa sylvatica); mockernut 
hickory (Hicoria alba) ; Kentucky coffee-tree (Gym- 
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