PREFACE xiii 



with numerous illustrations; the work of Fletcher and Clark of 

 Canada; Bolley's "North Dakota Weeds;" Blatehley's "Indiana 

 Weed Book;" W. J. Beal's "The Weeds of Michigan." A list of 

 these publications and where they may be obtained will be found 

 in the bibliography. 



Ames, Iowa, December 18, 1912. 



L. H. PAMMEL. 



