BugwoodWiki Article

Japanese knotweed
Fallopia japonica (Houttuyn) Ronse-Decraene

Overview

Appearance
Fallopia japonica is an upright herbaceous perennial shrub reaching heights of 10 ft. (3 m). The semi-woody stem is hollow with enlarged nodes.
Foliage
Leaves are alternate, 6 in. (15.2 cm) long, 3-4 in. (7.6-10 cm) wide and broadly-ovate. Leaf tips are abruptly acuminate and the bases are truncate.
Flowers
Flowering occurs in late summer, when small, greenish-white flowers develop in long panicles in the axils of the leaves. Plants are dioecious (male and female flowers occur on separate plants).
Fruit
The fruit are papery and winged, containing shiny, black, three angled achenes.
Ecological Threat
Fallopia japonica commonly invades disturbed areas with high light, such as roadsides and stream banks. Reproduction occurs both vegetatively (rhizomes) and seeds, making this plant extremely hard to eradicate. The dense patches shade and displace other plant life and reduce wildlife habitat. This plant is native to eastern Asia and was first introduced into North America in the late 1800s.

Resources

Selected Images


5205098
5205098

Japanese knotweed
Fallopia japonica
Flower(s)
Jan Samanek
1196197
1196197

Japanese knotweed
Fallopia japonica
Plant(s)
Nanna Borcherdt
5379559
5379559

Japanese knotweed
Fallopia japonica
Stem(s)
Steve Manning
5271087
5271087

Japanese knotweed
Fallopia japonica
Foliage
Leslie J. Mehrhoff
5271085
5271085

Japanese knotweed
Fallopia japonica
Flower(s)
Leslie J. Mehrhoff
5205099
5205099

Japanese knotweed
Fallopia japonica
Fruit(s)
Jan Samanek
0581045
0581045

Japanese knotweed
Fallopia japonica
Fruit(s)
Jil Swearingen
1550182
1550182

Japanese knotweed
Fallopia japonica
Seed(s)
Ken Chamberlain
5421941
5421941

Japanese knotweed
Fallopia japonica
Stem(s)
James H. Miller
2189040
2189040

Japanese knotweed
Fallopia japonica
Stem(s)
Chris Evans
5331054
5331054

Japanese knotweed
Fallopia japonica
Infestation
Randy Westbrooks
1557030
1557030

Japanese knotweed
Fallopia japonica
Seedling(s)
Ohio State Weed Lab Archive
5308058
5308058

Japanese knotweed
Fallopia japonica
Plant(s)
USDA PLANTS Database

Maps


EDDMapS Distribution - This map is incomplete and is based only on current site and county level reports made by experts, herbaria, and literature. For more information, visit www.eddmaps.org

EDDMapS Distribution

State Regulated List - This map identifies those states that list this species on their regulated list. For more information, visit Invasive.org

State Regulated List

Most Troublesome / Most Common Agricultural Weed List
This map identifies those states that consider this species either most troublesome or most common in at least one commodity. For more information, visit the MTMC project page.

State Regulated List
Legend
   No Data for this state
   Troublesome or Common weed in one or more crops

Invasive Listing Sources

Taxonomic Rank

Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Subclass: Caryophyllidae
Order: Polygonales
Family: Polygonaceae
Genus: Fallopia

Other System Links

Plants: FAJA2
Bayer: POLCU
GRIN: 409771

Synonyms and Other Names

Other Common Names:
fleeceflower, Japanese bamboo

Related Scientific Names:

Polygonum cuspidatum Siebold & Zucc.(Synonym)
Reynoutria japonica Sieb. & Zucc.(Synonym)

Categories

Category: Forbs/Herbs
Category: Vines

References

Common Name Reference:

Scientific Name Reference: