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Botanical description

Fallopia japonica has hollow stems with distinct raised nodes that give it the appearance of bamboo, though it is not closely related[2]. Nodes are usually reddish in colour and stems range from green to reddish-brown during the growing season are often flecked and turn brown as they die back in winter[5][11]. The stems are profusely branched and often reach a height of between 1 - 4 metres tall during the growing season[11][2] though plants can be much smaller than this[2].

Shoots grow from underground rhizomes early in the spring. They grow rapidly and can attain full height by early summer[6].

The leaves are thick and tough in texture, with short petioles[11], broad oval with a truncated base, 7 - 14 cm long and 5 - 12 cm broad, with an entire margin. The flowers are small, cream or white, produced in erect racemes 6 - 15 cm long in late summer and early autumn[2].

Rhizomes have an orange centre and can extend up to 7 metres from the parent plant horizontally and down 3 metres vertically[12]


Toxic parts

Although no specific mention has been made for this species, there have been reports that some members of this genus can cause photosensitivity in susceptible people. Many species also contain oxalic acid (the distinctive lemony flavour of sorrel) - whilst not toxic this substance can bind up other minerals making them unavailable to the body and leading to mineral deficiency. Having said that, a number of common foods such as sorrel and rhubarb contain oxalic acid and the leaves of most members of this genus are nutritious and beneficial to eat in moderate quantities. Cooking the leaves will reduce their content of oxalic acid. People with a tendency to rheumatism, arthritis, gout, kidney stones or hyperacidity should take especial caution if including this plant in their diet since it can aggravate their condition[13].

Edible uses


An excellent source of vitamin A, along with vitamin C and the antioxidant flavonoid rutin. Provides potassium, phosphorus, zinc, and manganese[1][14]. An excellent source of resveratrol[9][6] which is believed to lower LDL cholesterol and reduce the risk of heart attacks[14].

The shoots are tart and tangy[14], an acid flavour that suggests comparisons with rhubarb[15][14] . They can be used as subsitutes for rhubarb in pies, fruit soups, jams etc[15][16].They have also been compared to asparagus[17][3][18][19][20][15].

Shoots, very young leaves

Peeled and cooked, salted as a Vegetable


Raw, Cooked, Ground as a Thickener, Flour

It is rather small and fiddly to utilize. The seed can also be ground into a powder and used as a flavouring and thickener in soups etc, or can be mixed with cereals when making bread, cakes etc.


Cooked as a Vegetable

Material uses

A yellow dye is obtained from the root[7][8]. The plant is potentially a good source of biomass. Plants can be grown to form a ground cover that will exclude all other growth[21]. It is best to use the sub-species compactum since this is less invasive[21].

Whole plant



Medicinal uses(Warning!)

The Japanese common name for F. japonica is Itadori, which can be translated as "pain puller" or "removes pain"[1][2][6]. It has a long history of use in the herbal medicine traditions of Japan, China and Korea[1][6]. In Japan and China it has been used for at least 2000 years[9].

Extensive research has been done on the plant due to its high levels of resveratrol[9] and its potential for treating neuro-degenerative diseases[6][9]. The plant has been found to have broad antibacterial, antifungal and antiviral actions[9].

The root of F. japonica is antibacterial, antiviral, antischistosomal, antispriochetal, antifungal, immunostimulant, immunomodulant, anti-inflammatory, angiogensis modulator, central nervous system (brain and spinal cord) relaxant, central nervous system protectant and anti-inflammatory, antioxidant, antiathersclerotic, antihyperlipidemic, antimutagenic, anticarcinogenic, angiogenesis modulator, antineoplastic, vasodilator, antiasthmatic, inhibits platelet aggregation, inhibits eicosanoid synthesis, antithrombotic, tyrosine kinase inhibitor, oncogene inhibitor, antipyretic, cardioprotective, analgesic, antiulcer (slightly reduces stomach acid and protects against stress ulcers), hemostatic, astringent.[9][6][22][23]

Called Hu zhang in traditional Chinese medicine (TCM) F. japonica is considered bitter, cold and is associated with the liver, gallbladder and lungs[6]. It is believed to invigorate the qi and blood and stop pain, clear heat and resolve toxins, transform phlegm and stop coughs[6]. In TCM it is used to treat arthritis, rheumatic pain, traumatic injury, jaundice, hepatitis, urinary disorders, constipation, menstrual disorders, kidney stones, gall stones, inflammation of the gallbladder (with damp heat or severe heat syndrome), trichomonas, bacterial vaginitis, hyperlipidemia, burns, hemorrhoids, carbuncles, skin infections, snake bites, dental caries.[6][9]

F. japonica is considered a very important herb in the treatment of Lyme disease (Lyme borreliosis) as it specifically addresses the central nervous system and neurological complications of infection, as well as killing the Lyme bacteria itself[6][9].

Contraindicated in pregnancy[6][9]. Otherwise F. japonica is considered a very safe herb[6][9].

Interactions: Caution should be used if taking insulin or other antidiabetic drugs[6]. It should not be used with blood-thining medications[6][9]. Discontinue use 10 days prior to surgery[6][9].

F. japonica is considered a safe herb to use regularly and in relatively large doses[6][9]. A toxic dose is considered to be around 75 grams for a 75kg person[9]. Side effects of too high a dose will usually be gastrointestinal in nature - dry mouth, bitter taste in mouth, nausea, vomiting, abdominal pain, gas and bloating, abdominal distension, diarrhea[9][6]. These are signs that the dosage should be reduced[6].


Crushed as an Antibacterial, astringent


Ecosystem niche/layer

Shrub, Herbaceous or Rhizosphere

Ecological Functions


F. japonica has been shown to not only tolerate but to also clean soils contaminated with zinc, lead and copper[6][9]. It is often found growing on sites of old zinc and copper mines and alongside heavily polluted waterways[6]. The plant removes toxins from the surrounding soil and concentrates them in its roots[9].

Erosion control

F. japonica thrives in riparian areas and grows in dense thickets[9][6][1] making it a particularly useful plant for erosion control[9][1].


Nothing listed.


Nothing listed.


Propagation by seed may be difficult as male plants with fertile pollen are rarely found outside Japan and China[9]. According to the Japanese Knotweed Alliance almost every plant found outside Japan [and China] is a clone from a single mother plant making F. japonica, in total biomass terms, "the biggest female in the world"[5]. F. japonica primarily reproduces by division of small pieces of root/rhizome[9][5].

Division in spring or autumn. Very easy, larger divisions can be planted out direct into their permanent positions. We have found that it is better to pot up the smaller divisions and grow them on in light shade in a cold frame until they are well established before planting them out in late spring or early summer.


Seed - sow spring in a cold frame. Seed - sow spring in a cold frame. Germination is usually free and easy. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in the summer if they have reached sufficient size. If not, overwinter them in a cold frame and plant them out the following spring after the last expected frosts.


A very easily grown plant, it succeeds in ordinary garden soil in sun or shade[24][25], though it prefers a moist soil in partial shade[26].

Japanese knotweed is an extremely invasive plant capable of sending up new shoots at a considerable distance from the main clump and also of growing up through tarmac[27]. It is considered to be a pest in many areas, where it is forming large clumps in the wild and out-competing native species. If grown in the garden it should be planted within a strong barrier to contain its roots. The sub-species compacta is only about 70cm tall and is far less invasive, but should still not be grown in small gardens[27].

Plants seem to be immune to the predations of rabbits[28]. Often cultivated as a dye and a medicinal plant[7][8]. Very closely related to P. conspicuum[29]. Dioecious, male and female plants must be grown if seed is required[29].


Problems, pests & diseases

Associations & Interactions

There are no interactions listed for Fallopia japonica. Do you know of an interaction that should be listed here? edit this page to add it.

Polycultures & Guilds

There are no polycultures listed which include Fallopia japonica.




None listed.


None listed.

Full Data

This table shows all the data stored for this plant.

Binomial name
Fallopia japonica
Imported References
Edible uses
Medicinal uses
Material uses & Functions
Edible uses
None listed.
Material uses
None listed.
Medicinal uses
None listed.
Functions & Nature
Provides forage for
Provides shelter for
Hardiness Zone
Heat Zone
full sun
partial shade
Soil PH
Soil Texture
Soil Water Retention
Environmental Tolerances
    Ecosystems [9][6][12][2]
    Native Climate Zones
    None listed.
    Adapted Climate Zones
    None listed.
    Native Geographical Range
    Native Environment
    Ecosystem Niche
    Root Zone Tendancy
    Deciduous or Evergreen
    Herbaceous or Woody
    Life Cycle
    Growth Rate
    Mature Size
    3 x 5
    Flower Colour
    Flower Type

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    "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki. "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki.

    "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki., "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki., "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki.

    "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki.

    "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki., "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki., "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki. "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki., "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki., "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki. "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki. "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki.

    "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki. "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki.


    1. ? Workman, Dion. [Itadori (Japanese knotweed)] Shikigami (2013/03/16)
    2. ? [Japanese Knotweed] Wikipedia (2013/03/16)
    3. ? 3.03.1 Elias. T. and Dykeman. P. A Field Guide to N. American Edible Wild Plants. Van Nostrand Reinhold ISBN 0442222009 (1982/01/01)
    4. ? McPherson. A. and S. Wild Food Plants of Indiana. Indiana University Press ISBN 0-253-28925-4 (1977/01/01)
    5. ? [What is Japanese Knotweed] Japanese Knotweed Alliance (2013/03/16)
    6. ? Scott, Timothy Lee. Invasive Plant Medicine: The ecological benefits and healing abilities of invasives. Healing Arts Press ISBN 978-159477305-1 (2010/03/01)
    7. ? Uphof. J. C. Th. Dictionary of Economic Plants. Weinheim (1959/01/01)
    8. ? Usher. G. A Dictionary of Plants Used by Man. Constable ISBN 0094579202 (1974/01/01)
    9. ? Buhner, Stephen Harrod. Healing Lyme: Natural healing and prevention of Lyme Borreliosis and its coinfections. Raven Press ISBN 0-9708696-3-0 (2005/03/01)
    10. ? A Barefoot Doctors Manual. Running Press ISBN 0-914294-92-X (2013/03/01)
    11. ? [Japanese Knotweed] King County, Washington (2013/03/16)
    12. ? 12.012.1 [Japanese Knotweed - Fallopia japonica] Northern Ireland Environment Agency (2013/03/16)
    13. ? Bown. D. Encyclopaedia of Herbs and their Uses. Dorling Kindersley, London. ISBN 0-7513-020-31 (1995/01/01)
    14. ? Brill, Steve. [Knotweed] Wildman Steve Brill (2013/03/16)
    15. ? Facciola, Stephen. Cornucopia II: A source book of edible plants. Kampong ISBN 978-0-9628087-2-2 (1999/03/01)
    16. ? Brill, Steve. Identifying and Harvesting Edible and Medicinal Plants: In wild (and not so wild) places. HarperCollins ISBN 0-688-11425-3 (1994/03/01)
    17. ? Harris. B. C. Eat the Weeds. Pivot Health (1973/01/01)
    18. ? Brooklyn Botanic Garden Oriental Herbs and Vegetables, Vol 39 No. 2. Brooklyn Botanic Garden (1986/01/01)
    19. ? Cite error: Invalid <ref> tag; no text was provided for refs named PFAFimport-1599
    20. ? Reid. B. E. Famine Foods of the Chiu-Huang Pen-ts'ao. Taipei. Southern Materials Centre (1977/01/01)
    21. ? 21.021.1 Thomas. G. S. Plants for Ground Cover J. M. Dent & Sons ISBN 0-460-12609-1 (1990/01/01)
    22. ? Duke, James. [Chemicals and their Biological Activities in: Fallopia japonica] Dr. Duke's Phytochemical and Ethnobotanical Databases (2013/03/17)
    23. ? Duke. J. A. and Ayensu. E. S. Medicinal Plants of China Reference Publications, Inc. ISBN 0-917256-20-4 (1985/01/01)
    24. ? F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press (1956/01/01)
    25. ? Sanders. T. W. Popular Hardy Perennials. Collingridge (1926/01/01)
    26. ? Phillips. R. & Rix. M. Perennials Volumes 1 and 2. Pan Books ISBN 0-330-30936-9 (1991/01/01)
    27. ? 27.027.1 Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press ISBN 0-333-47494-5 (1992/01/01)
    28. ? Thomas. G. S. Perennial Garden Plants J. M. Dent & Sons, London. ISBN 0 460 86048 8 (1990/01/01)
    29. ? 29.029.1 Ohwi. G. Flora of Japan. (English translation) Smithsonian Institution (1965/01/01)

    Cite error: <ref> tag with name "EFG" defined in <references> is not used in prior text.
    Cite error: <ref> tag with name "PFAFimport-215" defined in <references> is not used in prior text.
    Cite error: <ref> tag with name "PFAFimport-178" defined in <references> is not used in prior text.

    "image:Fallopia japonica.jpg|248px" cannot be used as a page name in this wiki.

    Facts about "Fallopia japonica"RDF feed
    Article is incompleteNo +
    Article requires citationsNo +
    Article requires cleanupNo +
    Belongs to familyPolygonaceae +
    Belongs to genusFallopia +
    Functions asPhytoremediation + and Erosion control +
    Has common nameJapanese knotweed +, Japanese bamboo + and Mexican bamboo +
    Has drought toleranceIntolerant +
    Has edible partShoots +, Very young leaves +, Seeds + and Stem +
    Has edible useVegetable +, Thickener + and Flour +
    Has fertility typeSelf sterile +
    Has flowers of colourwhite +
    Has flowers of typeDioecious +
    Has growth rateVigorous +
    Has hardiness zone5 +
    Has imageFallopia japonica.jpg +
    Has lifecycle typePerennial +
    Has material partWhole plant + and Roots +
    Has material useBiomass + and Dye +
    Has mature height3 +
    Has mature width5 +
    Has medicinal partRoots + and Leaves +
    Has medicinal useAntibacterial +, Antiviral +, Antischistosomal +, Antispriochetal +, Antifungal +, Immunostimulant +, Immunomodulant +, Anti-inflammatory +, Angiogensis modulator +, Central nervous system relaxant +, Central nervous system protectant and antiinflammatory +, Antioxidant +, Antiathersclerotic +, Antihyperlipidemic +, Antimutagenic +, Anticarcinogenic +, Angiogenesis modulator +, Antineoplastic +, Antirheumatic +, Antitussive +, Detoxicant +, Diuretic +, Expectorant +, Vasodilator +, Antiasthmatic +, Inhibits platelet aggregation +, Inhibits eicosanoid synthesis +, Antithrombotic +, Tyrosine kinase inhibitor +, Oncogene inhibitor +, Antipyretic +, Cardioprotective +, Analgesic +, Antiulcer +, Hemostatic +, Astringent +, Stasis eliminating + and Channel-deobstructant +
    Has primary imageFallopia japonica.jpg +
    Has root zoneDeep +
    Has search namefallopia japonica + and x +
    Has seed requiring scarificationNo +
    Has seed requiring stratificationNo +
    Has shade tolerancePartial shade +
    Has soil ph preferenceAcid +, Neutral + and Alkaline +
    Has soil teclayture preferenceClay +
    Has soil teloamyture preferenceLoamy +
    Has soil tesandyture preferenceSandy +
    Has soil water retention preferenceMoist +
    Has sun preferenceFull sun +
    Has taxonomy nameFallopia japonica +
    Has water requirementsmoderate +
    Inhabits ecosystem nicheShrub +, Herbaceous + and Rhizosphere +
    Is grown fromSeeds +
    Is herbaceous or woodyHerbaceous +
    Is taxonomy typeSpecies +
    Native to environmentRiparian +
    Native to geographical rangeChina +, Japan +, Korea + and Taiwan +
    Tolerates air pollutionNo +
    Tolerates maritime exposureNo +
    Tolerates nutritionally poor soilNo +
    Tolerates windNo +