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Relation of Climate to Vegetation. ; 118 
On this continent aione, there are wholly or in part, six 
distinct regions of vegetation, but in certain of these, at 
least, we note that the greatest range is from north to south, 
in consequence of which plants of widely different type and 
habits must be included in one common flora. Thus in the 
North American Forest Region, the flora of that portion 
lying north of the St. Lawrence and the Great Lakes is 
characterised bysuch trees as the white pine, spruce, hem- 
lock, willows, birches and poplars; while such types as the 
oak, walnut, magnolias, chestnuts and long leaved pines, 
belong to the southern portions ; the connection between 
these two groups being established through the maples, 
beeches and elms. 
We may now direct our attention to another mode of 
division based upon temperature and variations in type. 
If a person were to commence a journey at the equator, 
and follow due north until he reached the Pole, certain im- 
portant facts—changes in the character of the vegetation— 
would force themselves upon his attention and demand 
explanation, however unobservant he might be. Starting 
in a region of richly luxuriant vegetation, remarkable for 
its great variety of forms, rich foliage, brilliantly colored 
flowers, as well as the rapid growth and often great size of 
all forms of plant life, he would by almost imperceptible 
gradations, find all these characteristics changing, until, on 
reaching the Arctic Regions, he would discover himself 
landed in a waste devoid of trees, bearing but scanty spe- 
cimens of woody plants, which, instead of holding them- 
selves proudly aloft, would be found trailing close along the 
ground orstunted into a most unseemly condition, Lichen 
covered rocks and moss grown fields would everywhere pre- 
sent the characteristic forms of plant life, while here and 
there, between the rocks, dwarfed herbs would rear their 
disproportionately large and abundant flowers, to catch the 
scant blessings of an altogether too brief existence, From 
a region where all nature seems to glory in existence, where 
plants appear in their greatest number and variety, and life 
is a perpetual joy, our traveller has passed to another region 
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