72 



WEED FLORA OF IOWA 



Distribution. — Waste places, New Brunswick south to North 

 Carolina and west to Minnesota, Kansas, and Rocky mountains. 

 Widely distributed through cultivation but often becoming a 

 troublesome weed. In many parts of Iowa; reported from Story, 

 Dubuque, Clinton, Polk, Boone, Allamakee, Winneshiek, Marshall, 

 Grundy, Plymouth, Pottawattamie and other counties. 



Extermination. — Easily killed by cultivation. Practice rotation 

 of crops. 



Pellitory (Parietaria pennsylvanica Muhl.). 



Description. — A low, annual, simple, or sparingly branched mi- 

 nutely downy plant ; oblong-lanceolate, thin leaves with opaque dots ; 

 flowers monoeciously polygamous shorter than involucre ; glomerate 

 except in the lower axils ; stigma sessile. 



Fig. 39. Pellitory (Parietaria pennsylvanica). Common in shady places near 



buildings. 

 (Photographed by Hart.) 



