CHAPTER IX. 

 TABLE OF NOXIOUS WEEDS 



In the table which follows the most troublesome weeds 

 of North America have been given. No doubt there are 

 many other plants which should be classified as weeds, 

 but it is difficult to always draw a sharp line ; 

 moreover, it is a difficult matter sometimes to determine 

 the worst weeds for a given locality and even more diffi- 

 cult to determine the worst weeds for the entire country. 

 A weed may be very bad in Iowa and yet comparatively 

 harmless in Missouri, Arkansas, and Florida. For in- 

 stance, the sow thistle is certainly a very bad and 

 aggressive weed in the Canadian Northwest and on the 

 borders of North Dakota and Minnesota; the orange 

 hawkweed is a troublesome weed in the New England 

 states and New York, the same is true of the ox-eye 

 daisy, but it is not troublesome in Iowa, Nebraska, Kan- 

 sas, or Missouri. Quack grass is an extremely trouble- 

 some weed from the New England states to Minnesota 

 and is becoming troublesome in northern Iowa. 



Some years ago Dr. Byron D. Halsted published a 

 paper giving a scale of points of our worst weeds. 1 The 

 report was based upon reports received from more than 

 one hundred replies from different parts of the United 

 States. It was found that the following weeds were re- 

 ported the most frequently: 



Canada thistle 10 times, pigweed 10 times, purslane 14 

 times, cocklebur six times, and so on. That is to say the 

 correspondents mentioned these as the worst weeds in 

 their particular locality. 



Dr. Halsted considers the following as important in 



1 Proc. Soc. Prom. Agrl. Sci., 1889:43. 



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