826 WEED FTjORA OF IOWA 



Williams of South Dakota, Clinton of Illinois, Selby of Ohio, and 

 Wooten of New Mexico; in addition press notices on the subject 

 were published in agricultural journals during the years 1891- 

 1895. Since then there have been comparatively few accounts, ex- 

 cepting a few notes in 1911 and 1912 in the agricultural journals. 

 The chemistry of the weed has also been discussed by G. E. Patrick 

 of Iowa and by the Colorado Experiment Station. This weed was 

 considered so important that a number of northern states passed 

 laws looking for its extermination. A bill was introduced into 

 Congress by Senator Hansbrough in which congressional aid was 

 asked to exterminate it. 



The Canada thistle has been discussed by numerous writers both 

 in Europe and in the United States. The spread of this weed is 

 considered in another connection. We find, however, that mention 

 of this weed is made by Linnaeus in his Flora Lapponica, by 

 Ratzeburg in 1859, and by Darlington in 1853. More recently the 

 weed has received attention from such botanists as H. L. BoUey of 

 North Dakota, T. J. Burrill of Illinois, E. S. Goff of Wisconsin, 

 Fletcher and Clark of Canada, L. F. Henderson of Idaho, L. H. 

 Dewey of Washington, D. C, Prof. Howitt of Canada, and L. H. 

 Pammel. There have been many press notices in the agricultural 

 papers, particularly in the northern Mississippi Valley. Attention 

 may be called to those in Wallace's Farmer, Iowa Homestead, 

 Breeders' Gazette, Farmers' Review, Prairie Farmer and Success- 

 ful Farming. 



Another weed that attracted much attention a few years ago 

 was squirrel-tail grass or wild barley. This was discussed by C. S. 

 Crandall of Colorado, Hillman of Nevada, Nelson of Wyoming, 

 Wooten of New Mexico and Pammel of Iowa. 



Prickly lettuce has been discussed by Arthur of Indiana, Weed 

 of Ohio, Dewey of Washington, D. C, Morrow of Illinois, Pammel 

 of Iowa, and Fernald of Massachusetts. 



Buffalo bur has been discussed by Henry of Wisconsin, Halsted 

 and Pammel of Iowa, Clinton of Illinois, Harvey of Maine, and in 

 numerous press notices in the agricultural journals. 



Mustards of various kinds have been discussed by Dewey of 

 Washington, D. C, Clark and Fletcher of Canada, Hitchcock of 

 Kansas, Howitt of Canada and Pammel of Iowa. 



The perennial sow thistle has been discussed by the agricultural 

 press of Canada and in special treatises by Howitt and Fletcher 



