Japanese Knotweed
Reynoutria japonica, aka Polygonum cuspidatum
Embedded Files
"Polygonum cuspidatum" by Matt Lavin is licensed under CC BY-SA 2.0.
About
About
Reynoutria japonica, or Japanese Knotweed, is an herbaceous member of the buckwheat family from East Asia. People brought the plant as a decorative plant to restore streambanks. A single Japanese Knotweed plant can grow to over 11 feet tall and easily grow horizontally with its many rhizomes.
"Polygonum cuspidatum" by Matt Lavin is licensed under CC BY-SA 2.0.
"Polygonum cuspidatum" by Matt Lavin is licensed under CC BY-SA 2.0.
"Polygonum cuspidatum" by Matt Lavin is licensed under CC BY-SA 2.0.
Identifying Features
Alternating leaves that can be up to 6 inches long
Hollow stem with reddish-purple nodes where the leaves are
Small green-white flower clusters
Plants turn brown and die with the onset of frost
"Polygonum cuspidatum" by Matt Lavin is licensed under CC BY-SA 2.0.
"japanese knotweed" by dankogreen is licensed under CC BY 2.0.
Ecosystem Impacts
Ecosystem Impacts
Japanese Knotweed spreads through its root system, which can grow up to 65 feet long
Colonies of Knotweed can form from interconnected horizontal roots called "rhizomes"
When stressed, these rhizomes can break apart
Each fragment can form a fully functional clone of the parent plant
Because of its ability to spread, Japanese Knotweed can quickly crowd out native species
Removal Techniques
Removal Techniques
Japanese Knotweed spreads through its root system, which can grow up to 65 feet long
Colonies of Knotweed can form from interconnected horizontal roots called rhizomes
When stressed, these rhizomes can break apart
Each fragment can establish a fully functional clone of the parent plant
Because of its ability to spread, Japanese Knotweed can quickly crowd out native species
Native Alternatives
Native Alternatives
"Eupatorium perfoliatum - Common Boneset" by FritzFlohrReynolds is licensed under CC BY-SA 2.0.
Boneset
Member of the daisy family with white flowers
"Common buttonbush (Cephalanthus occidentalis)" by bob in swamp is licensed under CC BY 2.0.
Buttonbush
Round, white flowers which attract butterfiles and bees
"Elderberry (Sambucus canadensis)" by bob in swamp is licensed under CC BY 2.0.
Elderberry
Small white flowers and red, black, or yellow berries
"Salix caprea catkins 080315-1" by Aconcagua is licensed under CC BY-SA 3.0.
Pussy Willow
Small true with white-gray catkins
References
References
"Invasive Plants in Your Backyard!" by the Connecticut River Coastal Conservation District
Identifying Features
Removal Techniques
Native Alternatives
"Japanese Knotweed" on PennState Extension
About
Identifying Features
Ecosystem Impacts
Removal Techniques
"Japanese Knotweed" on the National Invasive Species Informational Center
Identifying Features
Ecosystem Impacts
Removal Techniques
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