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WEED FLORA OF IOWA 



FiQ. 74-A. Distribution of Night-flowering Catchfly. 



or clover seed containing catchfly should be thoroughly cleaned in 

 milla equipped with screens specially designed to remove this im- 

 purity, and should not be used on land that may later be required 

 for the production of alsiko seed." 



Cow-herb {Saponaria vaccaria L.). 



Description. — ^A glabrous annual, from 1-2 ft. high with opposite 

 ovate-lanceolate leaves ; flowers in oorymbed cymes ; calyx 5-angled, 

 enlarged and angled in fruit; petals pale red. 



Distribution. — This weed has long been known as troublesome in 

 grain fields of Europe, and is common in North America. It is com- 

 mon in Iowa only where wheat is grown. 



Extermination. — Clean seed sown in clean soil is the only method 

 of exterminating the weed. 



Clark and Fletcher suggest the following treatment : ' ' Sow clean 

 seed. Prevention is the best and least expensive method of fighting 

 it. It is a large showy plant and when not present in excessive num- 

 bers can easily be hand-pulled. The seed will not retain its vitality 

 long ; when land is seeded to timothy or western grass and left for a 

 few years, the supply of vital seeds in the soil will be greatly re- 

 duced, if not eutirely exhausted." 



