Vascular Plants of North Carolina
Section: Common Name: Scientific Name: Family:
Account for Giant Knotweed - Reynoutria sachalinensis   (F. Schmidt ex Maxomowicz) Nakai
Members of Polygonaceae:
Members of Reynoutria with account distribution info or public map:
Google Images
Section 6 » Family Polygonaceae
Show/Hide Synonym
Author(F. Schmidt ex Maxomowicz) Nakai
DistributionMostly Mountains, plus Orange County.

Native of eastern Asia; in N.A. Newf. to Ont. and WI, south to NC and TN; also LA. Also B.C. and MT south to ID and CA.
AbundanceVery rare.
HabitatRoadside banks, ditches, creek banks.
PhenologyFlowering and fruiting July-October.
IdentificationGiant Knotweed is more robust than Japanese Knotweed (R. japonica), attaining heights of 6-12 feet (or more). The leaves are similar but larger and with a cordate (not truncate) base. The inflorescences are similar to those of Japanese Knotweed -- narrow white racemes that are mostly erect.
Taxonomic CommentsNamed as Polygonum sachalinense in older references. A hybrid between R. japonica and R. sachalinensis has been reported from the NC mountains. See Weakley (2018) or FNA for ID criteria.

Other Common Name(s)
State RankSE
Global RankGNR
State Status
US Status
USACE-agcpUPL link
USACE-empUPL link
County Map - click on a county to view source of record.
Select a source
AllHerbaria
Select an occurrence type
AllCollection_non_natural