WEEDS 475 



everlastings are especially frequent in dry pastures. A few 

 ferns, such as the sensitive fern and the ostrich fern, 1 horse- 

 tails, rushes, sedges, many worthless coarse grasses, smart- 

 weeds, docks, some buttercups, mints, and the ironweeds are 

 common only in moist fields, meadows, and pastures. 



438. How to avoid weeds. The methods of destroying weeds 

 are fully discussed in treatises on agriculture. A great deal can 



FIG. 356. Tumbleweeds (Cycloloma) drifted into heaps by the wind 



be done toward the prevention of weeds by taking pains not 

 to use poor seed for the farm and garden, since the cheaper 

 kinds often contain many weed seeds. Stable and barnyard 

 manure frequently contains many seeds of the most objection- 

 able weeds, and in caring for lawns it is often found cheaper 

 to use ground bone or chemical fertilizers, such as superphos- 

 phate of lime, than to spread over the grass fertilizers which 

 may introduce multitudes of troublesome weeds. 



One of the most obvious means of keeping one's premises 

 free from weeds is not to allow them any avoidable breeding 



1 Onoclea. 



