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Japanese Knotweed

Scientific Name

Fallopia japonica (Houtt.) Ronse Decr. (ITIS)

Common Name

Japanese knotweed, fleeceflower, Mexican bamboo, huzhang


Polygonum cuspidatum Siebold & Zucc.; Reynoutria japonica Houtt.

Native To

Asia (Stone 2010)

Date of U.S. Introduction

Late 1800s (Stone 2010)

Means of Introduction

Introduced as an ornamental (Stone 2010)


Crowds out native species (Stone 2010)

Japanese knotweed

Japanese knotweed, foliage


Photo by Jack Ranney; University of Tennessee

Find more images


  • APHIS Issues Final Environmental Assessment for Biological Control of Japanese, Giant, and Bohemian Knotweeds

    • Nov 30, 2020
    • USDA. Animal and Plant Health Inspection Service.

    • The U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) has issued the final environmental assessment (EA) for releasing Japanese knotweed psyllid (Aphalara itadori) to manage Japanese, giant, and bohemian knotweeds (Fallopia japonica, F. sachalinensis, and their hybrid, F. x bohemica). After careful analysis, APHIS has determined that releasing Japanese knotweed psyllid within the continental United States is not likely to have a significant impact on the environment. Based on this determination, APHIS will not prepare an environmental impact statement and will begin issuing permits for the release of Japanese knotweed psyllid.

Distribution / Maps / Survey Status


Selected Resources

The section below contains highly relevant resources for this species, organized by source.

Council or Task Force
Federal Government
International Government
State and Local Government