1867.] DRUMMONJ) — DISTRIBUTION OF PLANTS. 167 



Viola sagittata Aiton, I have found at London, growing along 

 with other interesting plants, nearly side by side, on a gentle 

 slope, well exposed to the rays of the sun, and composed of a very 

 sandy clay. Mr. Macoun has found the same plants upon the 

 ridges of Northumberland County, growing with Anemone 

 cylindrical Gray, Linum Virginianum Linn., Trifolium sfo/<>- 

 niferum Muhl., Liatris cylindracea Michx., Aster ericoides 

 Linn., Rudbeckia hir ta Linn., Artemisia biennis Willd., and a few 

 others. Both southern and western forms require a higher degree 

 of heat than plants of our eastern districts, even under the same 

 parallel of latitude. As in many parts of Western Canada 

 similar ridges of sand and gravel occur, the circumstances 

 detailed are not of mere local interest. 



In connection with the subject of soils, Mr. Macoun points 

 out the fact, that in his neighbourhood, western plants, where not 

 aquatic, always occur in either a sandy soil, or a soil holding 

 much limestone gravel. My own observations at London, and 

 elsewhere, would tend to confirm this in regard to, at least, 

 some plants. 



The flora of the Lake Superior districts, in some of its features. 



is very different from that of other parts of Canada. Many of 



the familiar trees and herbaceous plants of the more southern 



parts of the province are absent, whilst there occur — mingling 



with the very large number of our more abundant species, and 



the few northern forms — a little assemblage of plants, more 



characteristic some of the western woody country and plains, 



and others of the middle and southern States. Additional species 



are met with upon the American side of the lake. Ranunculus 



abortivus Linn. var. micranthus Gray, Matricaria inodora Linn., 



Tanacetum Huronense Nutt., Senecio canus Hook., and some 



others, extend as far eastward as the Lake Huron shores, but the 



majority have only been found in the vicinity of Lake Superior] 



It is not difficult to account for their presence in these localities, 



but why do we not find them about Lakes Erie and Ontario, and 



farther eastward, as well as around the Upper Lakes ? Questions 



of a similar nature will occur to United States botanists. 



What precludes the eastward range of the characteristic vegetation 



of the western prairies, and of the central wooded plains of the 



continent ; and to what cause can be ascribed the very peculiar 



north-westward range of many American plants, by which they 



occur in Ohio, Michigan. Wisconsin and westward, am! about the 



