a few minutes at several other places, its average speed between 

 stations was something over 40 miles an hour; a little too fast 

 for the satisfactory identification of plants at close range. 



An unexpected difiiculty was presented by the fact that an 

 early snow had fallen the day before (not in Detroit but farther 

 east), while most of the trees were still in full leaf; and the ground 

 was covered a few inches deep most of the way from Charing 

 Cross to Shedden, a distance of nearly 50 miles, in Kent and 

 Elgin Counties. (Remnants of the same snowfall were seen in 

 New York state in the next few days.) That of course obscured 

 some of the smaller herbs, but did not interfere with the iden- 

 tification of the trees and shrubs. 



As this route was not very far from states that I had previously 

 explored, no unfamiliar plants were to be expected. In fact one 

 can go all the way from the northern boundary of the United 

 States, east of the looth meridian, to the North Pole, without 

 encountering any species of trees which do not occur in the United 

 States, with the possible exception of some recently described 

 (and perhaps not very distinct) species of Crataegus; and shrubs 

 and herbs unknown in this country must be scarce in the in- 

 habited parts of eastern Canada. 



Southern Ontario is the southernmost part of Canada (ex- 

 tending to latitude 42°), and probably also the warmest; and 

 many plants common in the United States occur there and no- 

 where else in the country. It has doubtless been traversed by 

 numerous botanists, but the botanical literature about it is 

 mainly floristic. In addition to the writings of the ^Nlacouns 

 and C. K. Dodge, Dr. C. D. Howe has described the forests 

 briefly on page 288 of the Naturalists' Guide to the Americas 

 (1926), giving percentage figures for some of the common trees, 

 but telling nothing about the shrubs and herbs. 



The country traversed is all underlaid by essentially horizontal 

 Paleozoic strata (Silurian and Devonian), mostly limestone, but 

 they are pretty well covered by glacial drift and lacustrine de- 

 posits. The only bed-rock seen was around Hagersville, in the 

 western edge of Haldimand County, about 55 miles from Niagara 

 Falls, where the limestone is near enough to the surface to be 

 quarried for cement making and other purposes. The glacial 

 drift is not very rocky, only a few boulders ha\ing been noticed 

 between Tilbury and Fletcher in Kent County, about 40 miles 



