Japanese Knotweed Reynoutria japonica HouttuynNon-native  -  Invasive    Synonyms: Fallopia japonica, Pleuropterus zuccarinii, Polygonum cuspidatum.
Kingdom Plantae   >   Division Tracheophyta   >   Class Magnoliopsida   >   Order Caryophyllales   >   Family Polygonaceae   >   Genus Reynoutria   

Description:

Compare Giant Knotweed, which has cordate (heart-shaped) leaf bases.

There are 434 records in the project database.

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Japanese Knotweed blooming on Swamp Road, Worcester Co., Maryland (8/31/2013). Photo by Bill Hubick. (MBP list)

An invasive species of concern in Maryland. Photographed here in Worcester Co., Maryland (6/17/2012). Brought to England as an ornamental species in 1825 and then introduced to the U.S. Read more. Photo by Bill Hubick. (MBP list)

Japanese Knotweed in Allegany Co., Maryland (8/30/2014). Photo by Kimberly Booth. (MBP list)

Japanese Knotweed in bloom along Potomac River near Sideling Hill Creek, Washington Co., Maryland (8/19/2012). Photo by Richard Orr. (MBP list)

Japanese Knotweed flowering in Charles Co., Maryland (8/26/2009). Invasive. Photo by Kerry Wixted. (MBP list)

Japanese Knotweed in Caroline Co., Maryland (8/28/2016). Photo by Wayne Longbottom. (MBP list)

The prolific seeds of the invasive Japanese Knotweed in Caroline Co., Maryland (9/22/2012). Photo by Jim Brighton. (MBP list)

Japanese Knotweed blooming in Montgomery Co., Maryland (8/19/2014). Photo by Elizabeth Miller. (MBP list)

Japanese Knotweed in Anne Arundel Co., Maryland (8/31/2017). Photo by Bill Harms. (MBP list)

Japanese Knotweed in Dorchester Co., Maryland (7/31/2016). Photo by Wayne Longbottom. (MBP list)

Japanese Knotweed in Harford Co., Maryland (4/12/2018). Photo by Josh Emm. (MBP list)

Japanese Knotweed in Montgomery Co., Maryland (6/5/2014). Photo by Elizabeth Miller. (MBP list)

Japanese Knotweed in Caroline Co., Maryland (9/4/2016). Photo by Wayne Longbottom. (MBP list)

Japanese Knotweed in Caroline Co., Maryland (9/11/2016). Photo by Wayne Longbottom. (MBP list)

Japanese Knotweed in Anne Arundel Co., Maryland (6/18/2011). Photo by Bill Harms. (MBP list)

Early spring growth of Japanese Knotweed at Governor Bridge Natural Area, Prince George's Co., Maryland (4/13/2013). Seek and destroy. Photo by Bill Hubick. (MBP list)

Japanese Knotweed in Garrett Co., Maryland (4/21/2017). Photo by Matt Tillett. (MBP list)

Japanese Knotweed in Howard Co., Maryland (5/22/2013). Photo by Joanne Solem. (MBP list)

Japanese Knotweed in fruit in Anne Arundel Co., Maryland (12/24/2018). Photo by Matthew Beziat. (MBP list)

Japanese Knotweed in Allegany Co., Maryland (4/17/2019). Photo by Kimberly Booth. (MBP list)

New Japanese Knotweed shoots in Howard Co., Maryland (3/28/2016). Photo by Nancy Magnusson. (MBP list)

Japanese Knotweed in Calvert Co., Maryland (11/5/2016). Photo by Bill Hubick. (MBP list)

Japanese Knotweed (winter aspect) in Harford Co., Maryland (12/6/2015). Photo by Bill Hubick. (MBP list)

Japanese Knotweed near Lost Lake in Baltimore Co., Maryland (3/27/2016). Photo by Bill Hubick. (MBP list)

Japanese Knotweed in Howard Co., Maryland (1/27/2021). (c) johnbotany, some rights reserved (CC BY-NC). Photo by John Hall. (MBP list)

Japanese Knotweed blooming in Howard Co., Maryland (9/13/1981). Photo by Robert Solem. (MBP list)

Japanese Knotweed in Baltimore Co., Maryland (6/8/2019). (c) rroberts6204, some rights reserved (CC BY-NC). Photo by rroberts6204 via iNaturalist. (MBP list)

Japanese Knotweed in Prince George's Co., Maryland (6/19/2019). (c) agelb, some rights reserved (CC BY-NC). Photo by agelb via iNaturalist. (MBP list)

Japanese Knotweed in Anne Arundel Co., Maryland (4/24/2020). (c) rfaitoute, some rights reserved (CC BY-NC). Photo by rfaitoute via iNaturalist. (MBP list)

Japanese Knotweed in Baltimore Co., Maryland (5/18/2020). (c) Dwight Johnson, all rights reserved. Photo by Dwight Johnson. (MBP list)


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MBP marks as "Invasive" any taxon listed in the Maryland Invasive Species Council (MISC) list of Invasive Species of Concern in Maryland. You can read their criteria and review the lists here: https://mdinvasives.org/species-of-concern/.

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