12 Canadian Record of Science. 
PRAIRIE GROUP. 
The plants peculiar to the prairies are of relatively recent 
creation—perhaps the most modern group of species exist- 
ing in America. The prairies, as I have elsewhere stated 
in this journal, are of comparatively recent origin, and, in 
some sections, are still in process of formation, and only 
since this formation of these prairies can we conceive it 
possible that plants to specially give them an individuality, 
were called into existence. The variation which gave rise 
to them was, no doubt, brought about by the very nature of 
the surroundings—the drier atmosphere, the lighter rain- 
fall, the greater exposure to the sun’s rays, the stronger 
winds, the different and more uniform soil, and the absence 
of any marked physical surroundings. That many of the 
flowers there have a wide range is readily understood from 
the facilities they have for diffusion. The vast expanse of 
generally treeless, level or relatively level plain, exposed to 
the uninterrupted play of winds, und the generally uniform 
soil over great stretches of country, afford an opportunity 
not elsewhere possible for the diffusion and propagation of 
seeds. The large representation of the Compositee—a com- 
paratively modern order—and the vast abundance of the 
individuals of certain species of this order, are noticeable. 
Of the influence of soils on vegetation, both in their 
chemical and mechanical combinations, there is no question, 
but this influence in Ontario and Quebec is chiefly observa- 
ble when considering local floras. Gravel ridges or a 
stretch of sand will be found frequented or deserted, as the 
case may be, by certain plants, but the causes which in dis- 
tant times produced these ridges or this sand operated with 
similar results here and there over vast sections. Other 
causes as well, acting simultaneously, or afterwards, mixed 
and distributed the surface soils everywhere in such a man- 
ner that it is difficult to indicate very broad areas of the 
country from Lake Superior eastward, where special soils, 
uniformily the same, are alone to be found to the exclusion 
of their occurrence elsewhere. Other influences acting 
over greater areas have, therefore, to be songht in study- 
