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 349 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)

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

Japanese Knotweed in Howard Co., Maryland (5/22/2013). Photo by Joanne Solem. (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 blooming in Howard Co., Maryland (9/13/1981). Photo by Robert Solem. (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 Baltimore Co., Maryland (5/18/2020). (c) Dwight Johnson, all rights reserved. Photo by Dwight Johnson. (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 Anne Arundel Co., Maryland (4/24/2020). (c) rfaitoute, some rights reserved (CC BY-NC). Photo by rfaitoute via iNaturalist. (MBP list)


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