WEEDS OF SPECIAL CROPS 6l 



especially in those west of the Mississippi river, there is 

 a larger proportion of native plants. The species vary in 

 different cities, in different years, and in different sea- 

 sons." 



These weeds can be removed by sowing these lots and 

 vacant areas with clover and grasses. These plants will 

 effectually prevent the growth of many weeds, except the 

 annual spear grass (Poa annua), dandelion, wild onion 

 (Allium vineale), star of Bethelem (Ornithogalum umbel- 

 latum) and cat's-ear (Hypochaeris) ; or they can be uti- 

 lized for the growth of vegetables, like the potato. 



Where there are large areas, these weeds can be kept 

 down by allowing sheep to graze ; this method is followed 

 in New York and Philadelphia. These animals are ex- 

 cellent lawn mowers. The driveways of parks and walks 

 can be kept clean by spraying with iron sulphate or some 

 other herbicide ; however, the iron sulphate will be more 

 effective than most of the other herbicides. The method 

 has been described in full in another connection. 



In many sitates there are laws on the extermination of 

 weeds, and while they may be enforced in the country, no 

 attention is paid to them in cities. The municipal author- 

 ities should enforce the laws. It may be necessary to 

 appoint a weed commissioner who shall work under the 

 authority of the street or park commissioner. Dewey 

 suggests that "a few good examples, which may be pro- 

 duced through individual effort or by the united action of 

 a small community, will demonstrate the practical utility 

 of the work and lead to its extension. Examples of this 

 kind are now found in many villages and suburban towns. 

 If the practice can be made general in the cities and 

 towns throughout the country it will cut off one of the 

 principal avenues for the introduction of foreign weeds." 



Roadside Weeds. There is very little excuse for the 

 appearance of many of the weeds that appear along road- 

 sides, the character of these differing only with the local- 



