Taxon  Report   10891 
Fallopia japonica  (Houtt.) Ronse Decr.
Japanese knotweed
Fallopia japonica
© 2005 Louis-M. Landry
Click on a photo to see it bigger.
Fallopia japonica
© 2011 Louis-M. Landry
Fallopia japonica, a dicot, is a perennial herb that is not native to California.
It is an invasive plant. The California Invasive Plant Council classifies its potential impact on native ecosystems as moderate - ALERT (plant profile / CalWeedMapper).

Interactive Distribution Map

Observation Hotline
(observation details + photos)

point, line, or polygon

one or more occurrences
within a 7.5-minute quadrangle

Plant Characteristics
and Associations

Bloom Period
Fallopia japonica
© 2006 Dr. Amadej Trnkoczy
Genus: Fallopia
escaped cultivar
Wetlands:Usually occurs in non wetlands, but occasionally found in wetlands [U.S. Fish & Wildlife Service.]
Name Status:
Accepted by TJM2
Alternate Names:
(according to)

TJM2: Polygonum cuspidatum
TJM2: Reynoutria japonica
More information about  Fallopia japonica
Photos on CalPhotos / Google Images
Jepson eFlora

Records from the Consortium of California Herbaria


Search (Flora of North America)

website references from Google

Suggested Citation
Calflora: Information on California plants for education, research and conservation,
with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria.
[web application]. 2016. Berkeley, California: The Calflora Database [a non-profit organization].
Available:   (Accessed: Oct 24, 2016).

The information on this page comes from diverse sources. None of the links are sponsored.