72 



WEED FLORA OF IOWA 



Distribution. — ^Waste places, New Brunswick south to North 

 Carolina and west to Minnesota, Kansas, and Kocky 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 {Pwrietwria pennsylvcmica 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. 



Fro. 39. Pellitory {Parietaria 'pennsylvanica) . Common in shady places near 



buildings. 

 (Fhotographed by Hart.) 



