IJO UNIVERSITY OF MISSOURI STUDIES [272 



338. P. erectum L. Tall knotweed. 

 Yards and roadsides; common. 



Ontario to the Northwest Territory; Georgia to Tex- 

 as and Colorado. 



339. P. aviculare L. Doorweed. 



Very common about houses and along paths and roads. 

 Europe, Asia and North America. 



340. P. acre H. B. K. [P. punctatum Ell.: Persicaria punc- 

 tata (Ell.) Small]. Water smartweed. 



Very common in low grounds and sandy flats, also in damp 

 yards. 

 Almost throughout America. 



341. P, Hydropiper L. {Persicaria Hydropiper (L.) 

 Opiz.]. Common smartweed. Water pepper. 



Common in waste places and low grounds. 

 Europe and North America. 



342. P, liydropiperoides Michx. {^Persicaria hydropiper- 

 oides (Michx.) Small]. Mild water pepper. 



Swales and low grounds. 



New Brunswick to Minnesota and California; Florida 

 to Mexico. 



343. P. emersum (Michx.) Britton [/". MuhlenbergiiW dits.']. 

 Swamp across Hinkson creek south of Columbia. 

 Maine and Ontario to the Northwest Territory and 



British Columbia; Virginia to Louisiana and Mexico. 



344. P. Persicaria L. \Persicaria Persicaria (L.) Small]. 

 Lady's thumb. 



Yards and fields; very common. 

 Europe, thence to all America. 



345. P. Pennsylvanicum L. [Persicaria Pennsylvanica {"L.) 

 Small]. 



Along streams and in wet grounds; common. 

 Nova Scotia to Minnesota and South Dakota; Florida 

 and Nebraska to Mexico. 



346. P. incarnatum Ell. [P. lapathifolium incarnatum 

 (Ell.) Wats.: Persicaria incartiata (Ell.) Small]. 



