92 



WEED FLORA OF IOWA 



Fig. 51-C. Smartweed (Polygonum pennsylvanicum) . 

 (Photographed by W. Newell.) 



Water Pepper (Polygonum hydropiper L.). 



Description. — Much like P. persicaria but more slender and often 

 decumbent ; flowers greenish on slender nodding spikes ; achenes dull 

 in color and the whole plant more or less acrid. 



Distribution. — "Water pepper is widely distributed in eastern 

 North America ; naturalized from Europe or may be indigenous in 

 the northwest. Widely distributed in Iowa. 



Extermination. — This weed is usually found in moist places and 

 is not very troublesome in cultivated fields except in low places. 

 Fields that are badly infested with it should be plowed and drained 

 and if possible some leguminous plants like alsike clover sown. 



