PLANTS OF IOWA 161 



2070. P. douglasii, Greene. Douglas' Knotweed. 

 Common north. 



2071. P. persicarioides, IT. B. K. Southwestern Persicaria. 



Not common. 



2072. P. opelousanum, Riddell. Opelousus Persicaria. 

 Not common. 



2073. P. hydropiperoides, Miehx. Mild Water Pepper. 

 Infrequent. 



2074. P. punctatum, Ell. Water Smart Weed. 

 Common. 



2075. P. orientale, L. Princess Feather. 



Introduced from India; in waste places near gardens. 



2076. P. rayi, Babingt. Ray's Knotweed. 

 Introduced from Europe. 



2077. P. erectum, L. Erect Knotweed. 

 Not common. 



2078. P. exsertam, Small. Long Fruited Knotweed. 

 Not common. 



2079. P. ramoissimum , Michx. Bushy Knotweed. 

 West, infrequent. 



2080. P. convolvalus, L. Black Bindweed. 

 A common introduced weed. 



2081. P. scandens, L. Climbing False Buckwheat. 

 Not common. 



2082. P. sagittatum, L. Arrow Leaved Tear Thumb. 

 In low grounds. 



2083. P. dumctorum, L. Hedge Buckwheat. 

 Frequent in thickets. 



2084. P. cuspidatum, Engelm. and Gray. Crested False 



Buckwheat. 

 Escaped from gardens. 



CHENOPODIACE.S. GOOSEFOOT FAMILY. 



Chenopodium, L. 



2085. C. album, L. Lamb's Quarters. 

 A common introduced weed. 



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