Invasive Plant SpeciesJapanese Knotweed

Created by Renee GarrettJune 21, 2011

Scientific Name: Polygonum cuspidatum (synonym) Fallopia japonicaTaxonomic Rank: Magnoliopsida>Polygonales>Polygonaceae (Buckwheat Family)

Common names: Japanese knotweed Fleeceflower Mexican bamboo Huzhang Crimson Beauty Reynoutria

Brill, Steve. "Shoots and Greens of Early Spring in North America.

" Wildman Steve Brill. Foraging with Wildman, n.d. Web. 17 June 2011.

Japanese Knotweed Dense growing perennial shrub-like plant reaching heights

of 10 ft.

"Knot 1." Online image. Devoid of Culture and Indifferent to the Arts. Web. 17 June 2011. <http://docaitta.blogspot.com/2011/02/foraging-3-easting-

dastardly-japanese.html>.

Identify Stems Semi-woody stem is hollow and

enlarged nodes.

"Hollow-speckled Stalk." Online image. Food Under Foot. Web. 17 June 2011.

<http://foodunderfoot.com/juicing-japanese-knotweed/comment-page-1>.

Identify Leaves Leaves are alternate and broadly ovate,

leaf base is truncate.

"Leaves." Online image. Virginia Tech Weed Identification Guide. Web. 16 June 2011. <http://www.ppws.vt.edu/scott/weed_id/polcu.htm>.

Identify Flowers

Flowering occurs in late summer, when small, greenish-white flowers develop in long panicles in the axils of the leaves.

Male and female flowers occur on separate plants.

Landry, Louis. "Japanese Knotweed Flower." Online image. 2005. CalPhotos. Web. 17 June 2011. <http://calphotos.berkeley.edu/cgi/img_query?query_src=photos_index&where-taxon=Polygonum+cuspidatum>.

Location It is found near water sources, such as

along streams and rivers, in low-lying areas, waste places, utility rights-of-way, and around old home sites.

"Infestation." Online image. Center for Invasive and Ecosystem Health. Web. 17 June 2011.

<http://www.invasive.org/browse/detail.cfm?imgnum=5271079>.

Identify Seeds Reproduction occurs both vegetative

(rhizomes) and seeds, making this plant extremely hard to eradicate.

"Growth Bud 2 - Rhizome." Online image. Cornwall Council. Web. 17

June 2011. <http://www.cornwall.gov.uk/default.aspx?page=13810>.

"Seeds of Knotweed." Online image. Colby-Sawyer College. Web. 17 June 2011. <http://www.colby-sawyer.edu/herbarium/invasive/invasive10.html>.

A native of Japan, China, and parts of Korea and Taiwan.

Introduced to the U.S. in the late 1800‘s from England.

Ornamental plant for erosion control& for landscape screening.

It is now found throughout the United States.

Rainey, Jack. "Foliage." Online image. Invasive Plants of Eastern United States. Web. 17 June 2011. <http://www.invasive.org/eastern/species/3414.html>.

Selected for Ornamental Beautyand Preventing Soil Erosion

Slattery, Britt. "Foliage and Flowers." Online image. Invasive Plants of Eastern United States. Web. 17 June 2011. <http://www.invasive.org/eastern/species/3414.html>.

Counties of Virginia

Natural Resource Conservation Service. United States Department of Agriculture, n.d. Web. 17 June 2011. <http://plants.usda.gov/java/profile?symbol=POCU6>.

Eight states list Japanese Knotweed as a Noxious Weed

Alabama WashingtonCalifornia ConnecticutMassachusettsNew HampshireOregonVermont

Plants Database. United States Department of Agriculture, n.d. Web. 17 June 2011. <http://plants.usda.gov/java/profile?symbol=POCU6>.

International Threat Known introduced range:

Australia, Belgium, Canada, Czech Republic, Denmark, France, Germany, Guernsey, Ireland, Isle of Man, Italy, New Zealand, Russian Federation, Saint Pierre and Miquelon, Slovakia, United States (USA), and United Kingdom (UK)

Fallopia japonica is now officially regarded as the most pernicious weed in the United Kingdom.

Global Invasive Species Database. Invasive Species Specialist Group, n.d. Web. 17 June 2011. <http://www.issg.org/database/species/ecology.asp?si=91&fr=1&sts=>.

Ranked Highly Invasive 2009 in Virginia

"Japanese Knotweed." Online image. Japanese Knotweed Alliance. Web. 17 June 2011.

Impact: Very Aggressive Species

The species forms dense stands that crowd out all other vegetation.

Degrading native plant and animal habitat.

This perennial plant is difficult to control because it has extremely vigorous rhizomes that form a deep, dense mat.

In addition, the plant can re-sprout from fragments; along streams, plant parts may fall into the water to create new infestations downstream.

"Japanese Knotweed." Invasive Plant Atlas of United States. Web. 17 June 2011. <http://www.invasiveplantatlas.org/subject.html?sub=3414>.

Management PlansChemical: Experience in other states where it is a serious pest

suggests that the best control method is prevention of establishment.

The plant should be eradicated as early as possible upon its appearance.

Cutting the stalks as often as three times during the growing season will offset growth of the rhizomes.

An application of a glyphosate herbicide, after cutting, has been found to be most effective.

"Invasive Alien Plant List." Natural Heritage. Virginia Department of Conservation and Recreation, n.d. Web. 16 June 2011. <http://www.dcr.virginia.gov/natural_heritage/documents/invlist.pdf>.

 

The psyllid The sap-sucking psyllid Aphalara itadori

"The psyllid ." Online image. Japanese Knotweed Alliance. Web. 16 June 2011.

Management PlansNatural Defense

Management Plans Other potential agent: the leaf-spot fungus Mycosphaerella polygoni-cuspidati

This leaf-spot fungus devastates Japanese knotweed in the field in the warmer months from June to October. It has never been recorded on any plant other than Japanese knotweed.

"The Leaf-spot Fungus ." Online image. Japanese Knotweed Alliance. Web. 16 June 2011.

Natural Plant Alternatives in Virginia

Common AlderBlack ChokeberryAlleghany ChinkapinNew Jersey TeaButton BushSilky DogwoodWintergreenBlack HuckleberryWitch HazelWinterberryMountain LaurelEvergreen Mountain Fetterbush

Natural Heritage: N ative Plants for Mountain Region. Virginia Department of Conservation and Recreation, n.d. Web. 17 June 2011. <http://www.dcr.virginia.gov/natural_heritage/nativeplants.shtml>.

Recipes For Japanese Knotweed

Shoots from mid-April to early May, can be eaten before the plant gets tough and woody.

An excellent source of vitamin A, along with vitamin C and its cofactor, the antioxidant flavonoid rutin. It provides potassium, phosphorus, zinc, and manganese. Also Japanese knotweed is an excellent source of resveratrol, the same substance in the skin of grapes and in red wine that lowers LDL (bad) cholesterol and reduces the risk of heart attacks.

Apple and Knotweed Pie

Knot Ice Cream

Knot Soup

Knotweed Sherbet

Steamed Knotweed Sesame

Strawberry-Knotweed Cobbler

Brill, Steve. "Shoots and Greens of Early Spring in North America." Wildman Steve Brill. Foraging with Wildman, n.d. Web. 17 June 2011.

Works Cited

Brill, Steve. "Shoots and Greens of Early Spring in North America." Wildman Steve Brill. Foraging with Wildman, n.d. Web. 17 June 2011.

Growth Bud 2 - Rhizome." Online image. Cornwall Council. Web. 17 June 2011. <http://www.cornwall.gov.uk/default.aspx?page=13810>.

"Hollow-speckled Stalk." Online image. Food Under Foot. Web. 17 June 2011. <http://foodunderfoot.com/juicing-japanese-knotweed/comment-page-1>.

"Infestation." Online image. Center for Invasive and Ecosystem Health. Web. 17 June 2011. <http://www.invasive.org/browse/detail.cfm?imgnum=5271079>.

Invasive Alien Plant List." Natural Heritage. Virginia Department of Conservation and Recreation, n.d. Web. 16 June 2011. <http://www.dcr.virginia.gov/natural_heritage/documents/invlist.pdf>.

"Japanese Knotweed." Invasive Plant Atlas of United States. n.p., n.d. Web. 17 June 2011. <http://www.invasiveplantatlas.org/subject.html?sub=3414>.

"Japanese Knotweed." Online image. Japanese Knotweed Alliance. Web. 17 June 2011.

"Knot 1." Online image. Devoid of Culture and Indifferent to the Arts. Web. 17 June 2011. <http://docaitta.blogspot.com/2011/02/foraging-3-easting-dastardly-japanese.html>.

Continued Works CitedLandry, Louis. "Japanese Knotweed Flower." Online image. 2005. CalPhotos. Web. 17 June 2011. <http://calphotos.berkeley.edu/cgi/img_query?query_src=photos_index&where-taxon=Polygonum+cuspidatum>.

"Leaves." Online image. Virginia Tech Weed Identification Guide. Web. 16 June 2011. <http://www.ppws.vt.edu/scott/weed_id/polcu.htm>.

"Native Plants in Mountains Brochure." Natural Heritage. Virginia Department of Conservation and Recreation, n.d. Web. 17 June 2011. <http://www.dcr.virginia.gov/natural_heritage/nativeplants.shtml>.

Natural Resource Conservation Service. United States Department of Agriculture, n.d. Web. 17 June 2011. <http://plants.usda.gov/java/profile?symbol=POCU6>.

Newcomb, Lawrence. Newcomb's Wildflower Guide. Boston, New York, London: Little, Brown and Company, 1977. Print.

"The psyllid." Online image. Japanese Knotweed Alliance. Web. 16 June 2011.

Rainey, Jack. "Foliage." Online image. Invasive Plants of Eastern United States. Web. 17 June 2011. <http://www.invasive.org/eastern/species/3414.html>.

Science Dictionary. The American Heritage Dictionary, n.d. Web. 17 June 2011. <http://dictionary.reference.com/browse/Invasive>.

"Seeds of Knotweed." Online image. Colby-Sawyer College. Web. 17 June 2011. <http://www.colby-sawyer.edu/herbarium/invasive/invasive10.html>.

Slattery, Britt. "Foliage and Flowers." Online image. Invasive Plants of Eastern United States. Web. 17 June 2011. <http://www.invasive.org/eastern/species/3414.html>.