744 



WEED FLORA OF IOWA 



Linnaeiis, the Swedish botanist, seems to have known the plant as 

 it occurred in eastern Europe. Prof. L. H. Dewey has given us a 

 good account of the introduction of this weed in the United States.* 

 It seems to have been first observed in Scotland, Bonhomme county, 

 South Dakota, in 1873 or 1874, the seed having been brought in 

 with flax seed. In 1877, it was reported from Yankton county; 

 five years later in the counties to the north and west of Bonhomme. 

 By 1888 it bad infested many of the counties east of Missouri river 

 and two years later practically all of the counties of South Dakota 

 and southern North Dakota. About the same time it invaded 



Fig. 561. Russian Thistle (Salsola kali var. tenuifolia) . Common in eastern 

 Europe. Introduced into the Dakotas, 1873 or 1874. Now common In 

 northern United States, particularly in the west 



(Drawing by Charlotte M. King.) 

 •Bull. Div. of Bot., U. S. Dept. of Agr. 15 :12. 1894. 



