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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:

  • Invasive Species Maps
    USDA. FS. Northern Research Station.
    Maps are organized for 43 invasive plant species into five categories: trees, shrubs, vines, herbs, and grasses. Select the desired species to view the distribution information for northern states.
  • Early Detection & Distribution Mapping System (EDDMapS) - Japanese Knotweed
    University of Georgia. Center for Invasive Species and Ecosystem Health.
    Provides state, county, point and GIS data. Maps can be downloaded and shared.



Selected Resources:

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Invasive Plants of Ohio: Fact Sheet 10 - Japanese Knotweed (PDF | 254 KB)
Ohio Invasive Plants Council.
Included as one of the worst invasive plant species in Ohio's natural areas; for others see Invasive Plants of Ohio.

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

Fact Sheet: Japanese Knotweed (Jan 2014; PDF | 874 KB)
Alberta Invasive Plants Council (Canada).


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.

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.

Japanese Knotweed
Great Britain Non-Native Species Secretariat.

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


Germplasm Resources Information Network (GRIN) - Reynoutria japonica
USDA. ARS. National Genetic Resources Program.

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.

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

Japanese Knotweed
Cornwall County Council (United Kingdom).


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

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

Japanese Knotweed (May 2011; PDF | 671 KB)
Missouri Department of Conservation.

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

Japanese Knotweed - Vermont Invasive Exotic Plant Fact Sheet (PDF | 94 KB)
Vermont Agency of Natural Resources. Environmental Conservation.

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

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

Japanese Knotweed
King County (Washington). Noxious Weed Control Program.

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).

Japanese Knotweed
Plant Conservation Alliance. Alien Plant Working Group.


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: Jun 16, 2016
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