PLANTS Profile for Polygonum amphibium (water knotweed)

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PLANTS Profile

Polygonum amphibium L.
water knotweed


Symbol:		POAM8
Group:		Dicot
Family:		Polygonaceae
Growth Habit:		Forb/herb
Duration:		Perennial
U.S. Nativity:		Native

Click on the image below to enlarge it and download a high-resolution JPEG file.

Ray Schulenberg. USDA SCS. 1989. Midwest wetland flora: Field office illustrated guide to plant species. Midwest National Technical Center, Lincoln, NE. Courtesy of USDA NRCS Wetland Science Institute. Usage Guidelines.

More Information:

Plant Images:
Polygonum amphibium L.

Click on a thumbnail to view an image, or see all the Polygonum thumbnails at the PLANTS Gallery

Plant Distribution by State:
Polygonum amphibium L.

State Distributional Map for Polygonum amphibium L.

	See county distributions for the following states by clicking on them below or on the map.
	AR AZ CA CO CT DC DE IA ID IL IN KS KY LA MA ME MI	MN MO MS MT NC ND NE NH NJ NM NV NY OH OK OR PA RI	SC SD TN TX UT VA VT WA WI WV WY

Polygonum amphibium L. occures in the following states: Alaska, Arkansas, Arizona, California, Colorado, Connecticut, District of Columbia, Delaware, Iowa, Idaho, Illinois, Indiana, Kansas, Kentucky, Louisiana, Massachusetts, Maryland, Maine, Michigan, Minnesota, Missouri, Mississippi, Montana, North Carolina, North Dakota, Nebraska, New Hampshire, New Jersey, New Mexico, Nevada, New York, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Vermont, Washington, Wisconsin, West Virginia, Wyoming

Related Taxa:
Polygonum amphibium L.

View 33 genera in Polygonaceae, 80 species in Polygonum or click below on a thumbnail map or name for species profiles.

Polygonum amphibium var. emersum
longroot smartweed

Polygonum amphibium var. stipulaceum
water smartweed

Classification:
Polygonum amphibium L.

Click on a scientific name below to expand it in the PLANTS Classification Report.


Kingdom	Plantae – Plants
Subkingdom	Tracheobionta – Vascular plants
Superdivision	Spermatophyta – Seed plants
Division	Magnoliophyta – Flowering plants
Class	Magnoliopsida – Dicotyledons
Subclass	Caryophyllidae –
Order	Polygonales –
Family	Polygonaceae – Buckwheat family
Genus	Polygonum L. – knotweed
Species	Polygonum amphibium L. – water knotweed

Noxious Weed Information:
Polygonum amphibium L.

The related entity italicized and indented above is listed by the U.S. federal government or a state. Common names are from state and federal lists. Click on a place name to get a complete noxious weed list for that location.

California:
Polygonum amphibium L. var. emersum Michx.
kelp		C list (noxious weeds)

Invasive Information:
Polygonum amphibium L.

water knotweed

This plant is considered invasive by the authoritative sources noted below. This plant may be known by one or more common names in different places, and some are listed above. Click on an acronym to view each invasive plant list, or click here for a composite list of Invasive Plants of the U.S.

SWSS

Southern Weed Science Society. 1998. Weeds of the United States and Canada. CD-ROM. Southern Weed Science Society. Champaign, Illinois.

Wetland Indicator Status:
Polygonum amphibium L.

Nat. Ind.

Reg. 1

Reg. 2

Reg. 3

Reg. 4

Reg. 5

Reg. 6

Reg. 7

Reg. 8

Reg. 9

Reg. 0

Reg. A

Reg. C

Reg. H

OBL

Other Species Accounts and Images:
Polygonum amphibium L.

View photographs from CalPhotos.

View species account from ARS Germplasm Resources Information Network (GRIN).

View taxonomic account from Integrated Taxonomic Information System (ITIS) for ITIS Taxonomic Serial Number 20865.

View photographs and distribution from University of Tennessee Herbarium.

View species account, photographs, and distribution from Wisconsin State Herbarium (UW-Madison).