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You are here: Home / Plants / Species Profiles / Japanese Knotweed
Species Profiles

Japanese Knotweed

Japanese Knotweed

Scientific name: Fallopia japonica (Houtt.) Ronse Decr. (ITIS)

Synonym: Polygonum cuspidatum Siebold & Zucc.; Reynoutria japonica Houtt.

Common names: Japanese knotweed, fleeceflower, Mexican bamboo, huzhang

Click image to enlarge

Selected Resources

Native To: Asia (Stone 2010)

Date of U.S. Introduction: Late 1800s (Stone 2010)

Means of Introduction: Introduced as an ornamental (Stone 2010)

Impact: Crowds out native species (Stone 2010)

Current U.S. Distribution:



Selected Resources:

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Council or Task Force

Invasive Plants of Ohio: Fact Sheet 10 - Japanese Knotweed (PDF | 254 KB)
Ohio Invasive Plants Council.
See also: Invasive Plants of Ohio for worst invasive plant species identified in Ohio's natural areas

Southeast Exotic Pest Plant Council Invasive Plant Manual - Japanese Knotweed
Southeast Exotic Pest Plant Council.

Priority Species: Japanese Knotweed
Washington State Recreation and Conservation Office. Washington Invasive Species Council.

Fact Sheet: Japanese Knotweed (Jan 2014; PDF | 874 KB)
Alberta Invasive Species Council (Canada).
See also: Fact Sheets for more information about individual invasive species, including those listed as "Prohibited Noxious" and "Noxious" under the Alberta Weed Control Act


Alaska Exotic Plants Information Clearinghouse (AKEPIC): Species Biography - Japanese Knotweed, Giant Knotweed, Bohemian Knotweed (Feb 7, 2011; PDF | 304 KB)
University of Alaska - Anchorage. Alaska Center for Conservation Science.
See also: Non-Native Plant Species List for additional factsheets (species biographies) and species risk assessment reports of non-native species present in Alaska and also non-native species currently not recorded in Alaska (potential invasives).

Invasive Plant Atlas of New England (IPANE) - Japanese knotweed, Mexican bamboo
University of Georgia. Center for Invasive Species and Ecosystem Health.

Invasive Plant Atlas of the United States - Japanese Knotweed
University of Georgia. Center for Invasive Species and Ecosystem Health.

New York Invasive Species Information - Japanese Knotweed
New York Invasive Species Clearinghouse.

Least Wanted: Alien Plant Invaders of Natural Areas Fact Sheet - Japanese Knotweed
Plant Conservation Alliance. Alien Plant Working Group.

Invasive Species Compendium - Fallopia japonica
CAB International.

Japanese Knotweed Alliance
CABI Bioscience.

Delivering Alien Invasive Species Inventories for Europe (DAISIE): Species Factsheet - Fallopia japonica
European Commission. Sixth Framework Programme.

Non-native Species Information: Japanese Knotweed
Great Britain Non-Native Species Secretariat.

Global Invasive Species Database - Fallopia japonica (herb, shrub)
IUCN. Species Survival Commission. Invasive Species Specialist Group.

Invaders Factsheet: Japanese Knotweed
Ontario's Invading Species Awareness Program (Canada).

Federal Government

U.S. National Plant Germplasm System - Reynoutria japonica
USDA. ARS. National Genetic Resources Program. GRIN-Global.

Fire Effects Information System (FEIS) - Polygonum sachalinense, P. cuspidatum, P. bohemicum
USDA. FS. Rocky Mountain Research Station. Fire Sciences Laboratory.

PLANTS Database - Japanese Knotweed
USDA. NRCS. National Plant Data Center.

International Government

Weeds in Australia - Japanese Knotweed (Fallopia japonica)
Australian Government. Department of the Environment and Energy.

Japanese Knotweed
Cornwall County Council (United Kingdom).

State Government

Encycloweedia: Data Sheet - Fallopia genus
California Department of Food and Agriculture.
Included on California's noxious weed list; see Encycloweedia: Program Details for additional resources.

Noxious Weed Species - Japanese, Giant, and Bohemian Knotweeds
Colorado Department of Agriculture. Conservation Services Division. Noxious Weed Program.

Invasive Plant Species Fact Sheet: Japanese Knotweed (2006; PDF | 734 KB)
Indiana Department of Natural Resources. Invasive Plant Species Assessment Working Group.
See also: Species Assessments and Invasive Species for exotic animal and plant pests invading Indiana, causing economic and visual damage.

Invasive Species Best Control Practices - Japanese Knotweed (2012; PDF | 2.30 MB)
Michigan Department of Natural Resources. Michigan Natural Features Inventory.

Field Guide: Invasive - Japanese Knotweed
Missouri Department of Conservation.

Fact Sheet: Japanese Knotweed (Polygonum cuspidatum) (2014; PDF | 237 KB)
New Hampshire Department of Agriculture, Markets, and Food. Division of Plant Industry.
See also: New Hampshire's Prohibited Invasive Plant Fact Sheets for additional invasive trees, shrubs, vines, and herbaceous plants

Invasive Plants in Pennsylvania: Japanese Knotweed and Giant Knotweed (PDF | 162 KB)
Pennsylvania Department of Conservation and Natural Resources.

See also: Invasive Plants fact sheets (scroll to view) for plant species (trees, shrubs, vines, herbs and aquatic plants) that have impacted the state's natural lands

Non-Native Freshwater Plants - Japanese Knotweed
Washington State Department of Ecology. Water Quality Program.

Class B Noxious Weed: Japanese Knotweed
Washington State Noxious Weed Control Board.

King County (Washington) Noxious Weed Control Program - Japanese Knotweed
King County Department of Natural Resources (Washington). Water and Land Resources Division.

Japanese Knotweed (Polygonum cuspidatum)
Wisconsin Department of Natural Resources.


Japanese Knotweed (Polygonum cuspidatum) (2007; PDF | 117 KB)
Purdue University (Indiana). Extension.

Maine Invasive Plants Bulletin: Japanese Knotweed / Mexican Bamboo
University of Maine Cooperative Extension.
See also: Maine Invasive Plants & Entire Series for entire series of 22 fact sheets and invasive plants brochure (available in HTML/PDF or for purchase)

Invasive, Exotic Plants of the Southeast - Japanese Knotweed
North Carolina State University. Cooperative Extension. Going Native: Urban Landscaping for Wildlife with Native Plants.

Introduced Species Summary Project - Japanese Knotweed
Columbia University. Center for Environmental Research and Conservation.

Ohio Perennial & Biennial Weed Guide - Japanese Knotweed
Ohio State University. Ohio Agricultural Research and Development Center.

Fact Sheet: Japanese Knotweed (PDF | 367 KB)
Pennsylvania State University. Pennsylvania Sea Grant.

Invasive Plants and Insects: Japanese and Giant Knotweed
Pennsylvania State University. Cooperative Extension.


BioBullies - Japanese Knotweed
Natural Biodiversity (Western Pennsylvania).
See also: Invasive Species Fact Sheets for the worst trouble-makers in the region, and also for additional trouble-makers for you to watch out for


Integrated Taxonomic Information System. Fallopia japonica. [Accessed Mar 19, 2015].

Stone, K.R. 2010. Polygonum sachalinense, P. cuspidatum, P. bohemicum. In: Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

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Last Modified: Sep 29, 2016
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