British North American Plants. 463 



able heights — elevated in these distant and somewhat colder 

 times to far greater heights, forming extensive and numer- 

 ous lofty mountain ranges everywhere, with successions of 

 individual peaks, on perhaps all of which ranges and peaks 

 were glaciers. Nothing short of this will explain the 

 results of glacier action, whilst, at the same time, it admits 

 of there being a northern temperate flora in the valleys 

 and on the plateaus, just as we now find occurs, though on 

 a smaller scale and under somewhat different circum- 

 stances, in central and southern British Columbia and in 

 Switzerland to-day. The sub-arctic and arctic plants 

 would be on the higher summits and on suitable situations 

 farther north, where the temperature was lower and the 

 summers shorter, or on the lake and sea shores in lower 

 latitudes, where the more equable temperature and cold 

 sea levels would lead them. 



The phsenogamous plants common to Europe and Canada 

 number 419, and adding to these the horsetails and ferns, 

 the number is increased to 450. Prof. Asa Cray gives 320 

 species as the flowering plants common to the Northern 

 United States and Europe. This number, however, pre- 

 sently includes Lythrum hyssopifolia, L., Salicornia fruticosa, 

 L., Narthecium ossifragum, Huds., nine carices and grasses, 

 and Asplenium ruta-muraria, none of which have been decected 

 thus far in Canada. This indicates that there are about 

 112 species, chiefly arctic and sub-arctic, confined, in their 

 American range, to Canada. An analysis of the Canadian 

 species indicates how the following leading orders are 

 represented : — 



Species. Species. 



Ranunculaceae 18 Scrophulariacese . . 14 



Cruciferge , 24 Naidacese 15 



Caryophyllaceae 23 Juncaceee 16 



Rosacese 19 Cyperacese 56 



Composite 21 Graminse 40 



Erieacese 22 Filices 23 



The representation of species is very disproportionate to 

 the importance, at this later day, of the orders. The great 

 order Composite, which now embraces about 390 species 



