DESCRIPTIVE MANUAL 



85 



Distribution. — Native in the northern hemisphere, Asia and North 

 America, common everywhere in Iowa in gardens and waste places. 

 Usually affected by a white mildew. 



Extermination. — This annual weed can be destroyed only by giv- 

 ing the soil on which it occurs cultivation. It frequents dry and 

 more or less beaten soil. Where it is abundant in lawns the soil 

 should be stirred and sown to white clover. 



Bushy Knotweed {Polygonum ramosissimum Mx.). 



Description. — An erect or ascending, green or yellowish green 

 smooth herb 2-4 ft. high ; leaves linear or lanceolate, tapering into a 

 petiole ; flowers inconspicuous, greenish ; stamens 3-6 ; style short ; 

 achene 3-<angled. 



Fig. 48. Bushy or Erect Knotweed {Polygonum ramosissimum). Common im 



fields. 

 (Photographed by Hart.) 



