1903-4. | How PuiantT LiFe 1s DistRIBUTED IN CANADA AND Why. 39 
this earlier period of our history, these species were present in Canada, 
and we can assume that they had here their place of origin, if there is 
nothing to indicate their presence at as early a period in Europe. Still 
further, in-the vast areas of exposed Laurentian and Huronian and other 
early formations, Canada has an old look and must have furnished a 
home through the long past ages for the growth and diffusion of northern 
temperate plant life when other sections of the globe have from time to 
time been under water. We may very reasonably conclude that here 
may have been the point of origin of many of these plants common to 
the two continents. There is even some direct evidence that in later 
Cretaceous times the relations of land and water must have been such as 
to allow migration between Europe and America. 
AGE OF CANADIAN FLORA. 
There are, it will be seen, some data on which to found opinions on 
the ages of some of the groups which make up our Canadian flora. The 
species, of whose presence in the early Eocene times there is some evi- 
dence, are the oldest known representatives of the existing flora. Next 
to these in age, as species, are the plants common to Europe and America, 
for they were already well distributed at the time of the deposition of 
the clays of the Ottawa and the Don Rivers. It is probable that many 
of the Arctic species may be equally old, whilst the American species, 
not also European in range, but which are denizens of Japan, may be 
contemporaneous or even earlier in origin. The hazel and the sensitive 
fern, for example, both now common to Canada and Japan, were known 
plants in the United States in Eocene times. The plants confined to 
British Columbia and southward form probably a later flora brought into 
existence after the first upheaval of the great mountain ranges there. 
Following on these older floras, but possibly contemporaneous in age with 
some of them, are the Boreal species on the headlands of Lake Superior, 
and the maritime plants, presently on the shores of the Great Lakes. 
The more recent creations are, without doubt, those species—well repre- 
sented by Composita—which frequent more especially the newer prairies 
of Manitoba and the North-West Territories. 
The vast changes which took place in Canada during tertiary and 
subsequent times suggest the struggle for existence which must have 
prevailed among the plants of these periods. What destruction of ani- 
mals as well as plants these changes must have occasioned! What 
adaptation to new conditions in which the survivors found themselves, 
must have resulted! What innate energy must have existed in the 
relatively few survivors of the earlier periods, which has enabled them 
to carry out all their functions of growth and reproduction during all 
these successive geological eras down to the present day! 
