60 WEEDS OF THE FARM AND GARDEN 



Texas the buffalo bur; the prickly poppy (Argemone 

 mexicana) is one of the most common weeds. 



Many of these annual weeds are easily exterminated 

 by cultivation, but attention must be paid to weeds which 

 occur in waste places where they produce seeds in enor- 

 mous quantities. Weed seeds often retain their vitality for 

 a considerable period of time. Even though the first crop 

 is removed, a second crop appears from, the seeds buried 

 somewhat deeper in the soil. 



Weeds of Vacant Lots. The vacant lots of all parts 

 of our country are a continual menace to the agricultural 

 community. Many of our worst weeds start in the city. 

 The writer has observed the spreading of orache (Atri- 

 plex) from a small beginning in an Iowa city over a con- 

 siderable area. There are hundreds of acres of Canada 

 thistle in Chicago, and in some streets much of the peren- 

 nial sow thistle, which is such a menace to the agricul- 

 ture of Canada, the eastern states, northern Minnesota 

 and North Dakota. The bouncing bet and toadflax are 

 spreading rapidly to the adjacent country from such cit- 

 ies as St. Paul, Minnesota, La Crosse, Wisconsin, and 

 Chicago. The unoccupied lands are great weed patches 

 and in most cases are very unsightly. 



In an interesting article on "Weedsi of Cities and 

 Towns" by Lyster H. Dewey, the statement is made that 

 "the weeds of cities and villages are usually of the mi- 

 gratory class, cosmopolitan in character, and capable of 

 thriving under a wide range of environment. According 

 to the early European works on botany, plants from 

 Asia, adventive in Europe, usually appeared first in 

 cities. Many of these plants* are found about the cities 

 and towns of this country. Others are native plants 

 which have withstood the changed conditions due to cul- 

 tivation and have acquired a weedlike habit. In the 

 eastern cities and in those on the Pacific coast Old World 

 species predominate, while in the cities of the interior, 



