WEEDS ALONG ROADSIDES 539 



and grow a cultivated crop. Whece this is not practicable, 

 repeated mowings when in blossom or cutting biennial and 

 perennial weeds below the surface of the ground will eventu- 

 ally weaken them and prevent their spread. Sheep render 

 great assistance in keeping down weeds in pastures. Among 

 the more common pasture weeds in different sections of the 

 country are squirrel-tail grass or wild barley, broom sedge, 

 blue vervain, sheep sorrel, Russian thistle, milkweed, mul- 

 lein, yarrow, and Canada, bull, and sow thistles. 



711. Roadside Weeds. The weeds of roadsides are 

 usually much the same as those of meadows and pastures, 

 though on new grading annual weeds are likely to make a 

 rank growth. Mowing two or three times during the season 

 to prevent the production of seed, and seeding the roadsides 

 heavily to grass and clover will keep down weeds and pre- 

 vent their spread to adjoining fields. The more common 

 weeds of roadsides are ragweed, kinghead, sunflowers, marsh 

 elder, cockle bur, bull thistle, Jimson weed, velvet weed, and 

 sweet clover. 



LABORATORY EXERCISES 



1. Let each member of the class bring in five weeds. Learn the 

 names of these weeds and describe their most important characteristics. 

 This study should include their habit of growth, duration and nature 

 of root system, time of seeding, seed habits, and characters which make 

 eradication easy or difficult. 



2. Make a study of weed seeds, so that each member of the class 

 will learn to recognize the more common weed seeds in various kinds 

 of field seeds. Samples of grain and forage-crop seeds brought in or 

 prepared, containing weed seeds, may be inspected and the weed seed 

 separated and identified. Many of the experiment stations put up 

 cases containing small samples of the more common weed seeds, which 

 may be obtained at small cost and used for purposes of identification. 

 Several of the Farmers' Bulletins listed at the end of this chapter will 



