Calflora
Taxon  Report   10891    
Fallopia japonica  (Houtt.) Ronse Decr.
Japanese knotweed
Fallopia japonica
© 2006 Dr. Amadej Trnkoczy
Photos from
CalPhotos / Calflora
Fallopia japonica
© 2005 Louis-M. Landry
Fallopia japonica
© 2011 Louis-M. Landry
Fallopia japonica, a dicot, is a perennial herb that is not native to California. Cal-IPC rating: Moderate

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
© 2018 Rachel Kesel
Communities: escaped cultivar

Wetlands: Occurs usually in non wetlands, occasionally in wetlands

Name Status:
Accepted by JEF

PLANTS accepted name:
Polygonum cuspidatum

Alternate Names:
ICPN: Polygonum cuspidatum
ICPN: Reynoutria japonica
ICPN: Fallopia japonica var. japonica
More information about  Fallopia japonica
Photos on PlantID.net   /   Google Images
Jepson eFlora

Records from the Consortium of California Herbaria

USDA PLANTS Profile (POCU6)

Search efloras.org (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]. 2018. Berkeley, California: The Calflora Database [a non-profit organization].
Available: https://www.calflora.org/   (Accessed: Oct 23, 2018).

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