178 



AGRONOMY 



(Lepidiwm), chickweed (Stellaria), knotgrass (Polyyonum), 

 burdock (Arctiwny, evening primrose (Oenothera'), sneezeweed 

 (Helenium), bugloss (Echiwrn), bouncing Bet (Saponaria), 

 toadflax (JLinaricf), smartweed (Polyyonum), dog fennel (An- 

 themis), and Jimson weed (Datura). These may be looked up 

 in any botanical manual. A large number of other plants, 

 such as yarrow (AchillecC) and sheep sorrel (Oxalis'), come 



Photograph from American Steel and Wire Co. 



FIG 128. A plant of dog fennel, a common weed along roadsides and in 



low grounds 



under the designation of weeds, since they frequently grow 

 among cultivated crops, but they are seldom harmful enough 

 to be classed with the noxious species and are not difficult 

 to eradicate. 



It should not be supposed that the plants we now recognize 

 as weeds are the only ones with which the cultivator is likely 

 to have to contend. New weeds are practically certain to ap- 

 pear from time to time, either derived from our native flora 



