458 



Plant Physiology 



(1) Upon ground where no vegetation is desired walks, 

 playgrounds, courtyards, etc. 



FIG. 133. Natural growth of dandelions in an untreated lawn. [Photo- 

 graph by H. L. Bolley.] 



(2) When particularly undesirable weeds are present in 

 small spots, and the temporary suppression of all growth 

 is not a serious objection. 



