Polygonum erectum L.
Coefficient of Conservatism: 0
Coefficient of Wetness: 3
Wetness Index: FACU
Physiognomy: Nt A-Forb

Considered a native American plant, but not collected in Michigan before 1861 or after 1939. During that 80-year period, recorded from farmyards, roadsides, and disturbed places.

Other species have frequently been misidentified as this one. The knotweeds are often troublesome to determine, as any of the characters cited is open to exception and one must sumetimes make a judgment on a balance of characters. The leaves of P. erectum may be similar to the shapes in P. aviculare, but run distinctly larger. Mature plants are rather strongly heterophyllous, with flowers (fruits) in axils of much-reduced leaves or bracts.

This species, represented by a now extinct larger-fruited cultivar, was apparently a significant crop for native peoples in eastern North America. See Mueller (2018) for details. 


Cheboygan County
Emmet County
Gratiot County
Jackson County
Kalamazoo County
Kent County
Keweenaw County
Manistee County
St. Clair County
Van Buren County
Washtenaw County
Wayne County


MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. June 29, 2022. https://michiganflora.net/species.aspx?id=2297.