Common Name: ERECT KNOTWEED
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 too often 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.

B. S. Walters

Click image to view gallery

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

Citation:
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. March, 17, 2025
https://lsa-miflora-p.lsait.lsa.umich.edu/#/record/2297