For some time it has been realized that the grassland occuring in the 'park belt' or 'aspen grove region' bounding the Canadian prairies on the north, and forming the transition between it and the boreal forest, does not consist merely of extensions of the adjacent grassland communities (true prairie or mixed prairie) among the patches of woodland which occur in that region; but is characterized by a different group of dominant grasses from those occuring elsewhere in North America. Although other investigators have mentioned this fact and written about the flora in other parts of the region, their data have been based largely on methods of estimation chiefly of a qualitative nature. In view of this, it was thought that an ecological survey...