Fallopia sachalinensis - (F. Schmidt ex Maxim.) Dcne.
Giant Knotweed
Other Common Names: giant knotweed
Synonym(s): Polygonum sachalinense F. Schmidt ex Maxim. ;Reynoutria sachalinensis (F. Schmidt ex Maxim.) Nakai
Taxonomic Status: Accepted
Related ITIS Name(s): Polygonum sachalinense F. Schmidt ex Maxim. (TSN 20923)
French Common Names: renouée de Sakhaline
Unique Identifier: ELEMENT_GLOBAL.2.151038
Element Code: PDPGN0L230
Informal Taxonomy: Plants, Vascular - Flowering Plants - Buckwheat Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Polygonales Polygonaceae Fallopia
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Polygonum sachalinense
Taxonomic Comments: FNA (vol. 5, 2005) transfers Polygonum sachalinense to Fallopia sachalinensis. Schuster et al. (2011) transfer F. sachalinensis to Reynoutria sachalinensis.
Conservation Status
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NatureServe Status

Global Status: GNR
Global Status Last Changed: 22Mar1994
Rounded Global Status: GNR - Not Yet Ranked
Nation: United States
National Status: NNA
Nation: Canada
National Status: NNA (16Sep2014)

U.S. & Canada State/Province Status
United States California (SNA), Connecticut (SNA), Delaware (SNA), Idaho (SNA), Illinois (SNA), Kentucky (SNA), Louisiana (SNA), Maine (SNA), Maryland (SNA), Massachusetts (SNR), Michigan (SNA), New Jersey (SNA), New York (SNA), North Carolina (SNA), Ohio (SNA), Oregon (SNA), Pennsylvania (SNA), Rhode Island (SNA), Tennessee (SNA), Virginia (SNA), Washington (SNA), West Virginia (SNA)
Canada British Columbia (SNA), New Brunswick (SNA), Newfoundland Island (SNA), Nova Scotia (SNA), Ontario (SNA), Prince Edward Island (SNA), Quebec (SNA)

Other Statuses

NatureServe Global Conservation Status Factors

Other NatureServe Conservation Status Information

Distribution
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U.S. States and Canadian Provinces
Color legend for Distribution Map
NOTE: The distribution shown may be incomplete, particularly for some rapidly spreading exotic species.

U.S. & Canada State/Province Distribution
United States CAexotic, CTexotic, DEexotic, IDexotic, ILexotic, KYexotic, LAexotic, MA, MDexotic, MEexotic, MIexotic, NCexotic, NJexotic, NYexotic, OHexotic, ORexotic, PAexotic, RIexotic, TNexotic, VAexotic, WAexotic, WVexotic
Canada BCexotic, NBexotic, NFexotic, NSexotic, ONexotic, PEexotic, QCexotic

Range Map
No map available.

Ecology & Life History Not yet assessed
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Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank)
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Disclaimer: While I-Rank information is available over NatureServe Explorer, NatureServe is not actively developing or maintaining these data. Species with I-RANKs do not represent a random sample of species exotic in the United States; available assessments may be biased toward those species with higher-than-average impact.

I-Rank: High/Medium
Rounded I-Rank: High
I-Rank Reasons Summary: Polygonum sachalinense displaces streamside vegetation causing an increase in bank erosion and clogs small waterways. This plant forms thickets up to 12 feet tall and produces allelochemicals. It reduces the quality of riparian habitat for fish and wildlife. It is often found in riparian areas along riverbanks, railroad right-of-ways, and roadsides. This plant is widespread across the U.S. and appears to be a problem at least in Washington. Only produces a small amount of viable seed. Spreads mainly by rhizomes but also by fragments of root. Not much is known about managing this species. Take note that it produces viable pollen for Japanese knotweed (another non-native species) producing a fertile hybrid that is similar to Japanese knotweed in appearance and aggressiveness.
Subrank I - Ecological Impact: High/Medium
Subrank II - Current Distribution/Abundance: High/Medium
Subrank III - Trend in Distribution/Abundance: Unknown
Subrank IV - Management Difficulty: Unknown
I-Rank Review Date: 09Mar2004
Evaluator: Killeffer, T.
Native anywhere in the U.S?
Native Range: Asia (King Co. 2003).

Download "An Invasive Species Assessment Protocol: Evaluating Non-Native Plants for their Impact on Biodiversity". (PDF, 1.03MB)
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Screening Questions

S-1. Established outside cultivation as a non-native? YES
Comments: Kartesz 1999.

S-2. Present in conservation areas or other native species habitat? Yes
Comments: By the 1950's it was established in the eastern U.S. (WA Weed Control Board 2004).

Subrank I - Ecological Impact: High/Medium

1. Impact on Ecosystem Processes and System-wide Parameters:Moderate significance
Comments: Displaces streamside vegetation causing an increase in bank erosion and clogs small waterways (King Co. 2003). Produces allelochemicals (WA Noxious Weed Control Board 2004).

2. Impact on Ecological Community Structure:High/Moderate significance
Comments: Forms thickets up to 12 feet tall (King Co. 2003). Out competes native plants (WA Noxious Weed Control Board 2004).

3. Impact on Ecological Community Composition:High/Moderate significance
Comments: Displaces streamside vegetation, clogs waterways, Forms thickets up to 12 feet tall, and increases bank erosion all leading to a reduction in the quality of riparian habitat for fish and wildlife (King Co. 2003). Out competes native plants and produces allelochemicals (WA Noxious Weed Control Board 2004).

4. Impact on Individual Native Plant or Animal Species:Not ranked

5. Conservation Significance of the Communities and Native Species Threatened:High/Low significance
Comments: "Often found in riparian areas along riverbanks, railroad right-of-ways, and roadsides" (WA Noxious Weed Control Board 2004).

Subrank II. Current Distribution and Abundance: High/Medium

6. Current Range Size in Nation:High significance
Comments: Kartesz 1999.

7. Proportion of Current Range Where the Species is Negatively Impacting Biodiversity:High/Low significance
Comments: Little information available. Appears to be a problem at least in Washington.

8. Proportion of Nation's Biogeographic Units Invaded:High/Moderate significance
Comments: Between 30 - 44 in lower 48 plus Alaska (Kartesz 1999).

9. Diversity of Habitats or Ecological Systems Invaded in Nation:Low significance
Comments: Share habitat with Japanese knotweed - riparian areas, moist wet places, railroad right-of-ways, and roadsides (WA Noxious Weed Control Board 2004).

Subrank III. Trend in Distribution and Abundance: Unknown

10. Current Trend in Total Range within Nation:Not ranked

11. Proportion of Potential Range Currently Occupied:Not ranked

12. Long-distance Dispersal Potential within Nation:Medium/Low significance
Comments: Only produces a small amount of viable seed. Spread by fragments of root or rhizomes.
Fragments can be distributed by such events as flood, erosion, roadside clearing or fill dirt (WA Noxious Weed Control Board 2004).


13. Local Range Expansion or Change in Abundance:Not ranked

14. Inherent Ability to Invade Conservation Areas and Other Native Species Habitats:High/Low significance
Comments: "Often found in riparian areas along riverbanks, railroad right-of-ways, and roadsides" (WA Noxious Weed Control Board 2004).

15. Similar Habitats Invaded Elsewhere:High/Low significance
Comments: Found in Ireland in similar habitat (Hackney 2003). Also in Canada according to Kartesz (1999).

16. Reproductive Characteristics:Medium/Low significance
Comments: Only produces a small amount of viable seed. Spreads mainly by rhizomes but also by fragments of root. Cannot self-pollinate (WA Noxious Weed Control Board 2004).

Subrank IV. General Management Difficulty: Unknown

17. General Management Difficulty:Not ranked

18. Minimum Time Commitment:Not ranked

19. Impacts of Management on Native Species:Not ranked

20. Accessibility of Invaded Areas:High/Low significance
Comments: Riparian areas and moist wet places could be difficult to reach.

Other Considerations: It produces viable pollen for Japanese knotweed (another non-native species) producing a "fertile hybrid that is similar to Japanese knotweed in appearance and aggressiveness" (WA Noxious Weed Control Board 2004).
Authors/Contributors
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Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
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  • Flora of North America Editorial Committee. 2005. Flora of North America North of Mexico. Vol. 5. Magnoliophyta: Caryophyllidae: Caryophyllales, Polygonales, and Plumbaginales. Oxford Univ. Press, New York. vii + 656 pp.

  • Hackney, P. 2003. Flora of Northern Ireland. National Museums and Galleries of Northern Ireland and Environment and Heritage Service. Available: http://www.habitas.org.uk/flora/index.html. (Accessed 2004).

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.

  • King County Noxious Weed Control Board. 2003. Giant Knotweed: Polygonum sachalinense. Natural Resources and Parks, Water and Land Resources Division, Seattle, Washington. http://dnr.metrokc.gov/wlr/LANDS/Weeds/knotg.htm. Accessed 03/09/2004.

  • Meades, S.J. & Hay, S.G; Brouillet, L. 2000. Annotated Checklist of Vascular Plants of Newfoundland and Labrador. Memorial University Botanical Gardens, St John's NF. 237pp.

  • Washington State Noxious Weed Control Board. 2004. Giant Knotweed (Polygonum sachalinense F. Schmidt ex Maxim). Written Findings of the State Noxious Weed Control Board - Class B Weed. Online. http:// www.nwcb.wa.gov/weed_info/gknotweed.html. Accessed 3/9/2004.

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