POLYGONACEAE 79 



Outer calyx lobes winged and decurrent in fruit, achenes 4-5 mm. 



long. 24. P. scandens. 



Stems with recurved prickles. 25. P. sagitatum. 



1. Polygonum amphibium L. 

 Polygonum coccinea ]\Iuhl. 



In water or sometimes in muddy places. Peru; Richardson County; 

 Swan Lake. 



2. Polygonum hartwrightil A. Gray. 



In wet places and in shallow water; perhaps only a form of Polygonum 

 amphibium. Cherry County; Thedford; Valentine; Whitman. 



3. Polygonum emersum CNIichx.) Britton. 

 Polygonum muhlenberghil CNleisnr.) Wats. 



In wet places and in shallow water. Cherry County; Emerson; Ken- 

 nedy; Richardson County; Whitman. 



4. Polygonum incarnatum Ell. 



In wet soil, not common. Kennedy; Lincoln; Long Pine; Nemaha; 

 Red Cloud; Weeping Water. 



5. Polygonum lapathifolium L. 



A common weed in the eastern part of the state, less common in the 

 western part. Dawes County; Mullen; Paddock; Red Cloud; River- 

 ton; Talmage; Whitman. 



6. Polygonum pennsylvanlcum L. 

 Polygonum omissum Greene. 



Common as a troublesome weed throughout the state. Boelus; Frank- 

 lin; Indianola; Kearney; Lincoln; Mullen; Paddock; Red Cloud. 



7. Polygonum persicaria L. 



Common in the eastern part of the state. Bassett; Callaway; Lincoln; 

 Paddock; Valentine; Weeping Water. 



8. Polygonum perslcarloides H. B. K. 



Over most of the state but not common. Newark; Thedford. 



9. Polygonum hydropiperoides Michx. 



In wet soil, not very common. Ainsworth; Atkinson; Callaway. 



10. Polygonum hydropiper L. 



In the eastern part of the state. Callaway; Franklin; Grand Rapids; 

 Lincoln; Weeping Water; Nemaha. 



11. Polygonum punctatum Ell. 



Common in the eastern half of the state. Banner County; Grand 

 Island; Hooker County; Indianola; Lincoln; Wahoo. 



12. Polygonum punctatum var. leptostachyum (Meisn.) Sm.all. 

 Thomas County; Hooker County; Grant County. 



13. Polygonum verginianum L. 



Common in the southeastern part of the state. Endicott; Lincoln; 

 Nebraska City; Richardson County; Nemaha. 



14. Polygonum aviculare L. 



A common weed all over the state. Callaway; Ft. Robinson; Grand 

 Island; Kearney; Lincoln; Mullen; Pine Ridge; Talmage; Thedford. 



15. Polygonum buxiforme Small. 



Common all over the state. Alliance; Cheyenne County; Hooker 

 County; Mullen. 



16. Polygonum erectum Roth. 



Common in the eastern part of the state. Ewing; Ft. Robinson; Lin- 

 coln; Talmage. 



