A Guide to the Poisonous Plants and 
Weed Seeds of Canada and the 
Northern United States 
By 
R. B. Thomson, B.A., F.R.S.C. 
Associate Professor of Phanerogamic Botany 
and 
H. B. Sifton, M.A. 
Assistant Professor of Research in Botany 
UNIVERSITY OF TORONTO PRESS 
1922 
A 
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