84 



WEED FLORA OF IOWA 



Dooryard Knotweed {Polygonum aviculare L.) . 



Descriptioh. — ^A scattered or somewhat ascending, bluish grey an- 

 nual; leaves acute or acutish; flowers greenish with pinkish mar- 

 gins ; achenes triangular, dull and minutely granular-striate. 



Fio. 47. Dooryard Knotweed {Polygonum aviculare). Common In dooryards. 

 (Photographed by Hart.) 



Fig. 47-A. Distribution of Dooryard Knotweed. 



