Reynoutria sachalinensis
{{Short description|Species of flowering plant in the knotweed family Polygonaceae}}
{{Speciesbox
| image = GiantKnotweed053.jpg
| taxon = Reynoutria sachalinensis
| authority = (F.Schmidt) Nakai
| synonyms_ref = [http://www.theplantlist.org/tpl1.1/record/kew-2425431 The Plant List, Reynoutria sachalinensis (F.Schmidt) Nakai ]
| synonyms =
- Polygonum sachalinense F.Schmidt 1859
- Fallopia sachalinensis Ronse Decr.
- Reynoutria brachyphylla (Honda) Nakai
- Tiniaria sachalinensis (F. Schmidt) Janch.
}}
Reynoutria sachalinensis, the giant knotweed or Sakhalin knotweed, (syns. Polygonum sachalinense, Fallopia sachalinensis) is a species of Fallopia native to northeastern Asia in northern Japan (Hokkaidō, Honshū) and the far east of Russia (Sakhalin and the southern Kurile Islands).{{GRIN | accessdate = 1 January 2018}}
Reynoutria sachalinensis is a herbaceous perennial plant growing to {{convert|2|–|4|m|in|abbr=on}} tall, with strong, extensively spreading rhizomes forming large clonal colonies. The leaves are some of the largest in the family, up to {{convert|15|–|40|cm|in|round=0.5|abbr=on}} long and {{convert|10|–|28|cm|in|round=0.5|abbr=on}} broad, nearly heart-shaped, with a somewhat wavy, crenate margin. The flowers are small, produced on short, dense panicles up to {{convert|10|cm|in|round=0.5|abbr=on}} long in late summer or early autumn; it is gynodioecious, with male and female (male sterile) flowers on separate plants. The species is closely related to the Japanese knotweed, Reynoutria japonica, and can be distinguished from it by its larger size, and in its leaves having a heart-shaped (not straight) base and a crenate margin. Reynoutria sachalinensis has a chromosome count of 2n=44.Flora of NW Europe: [https://archive.today/20070621080912/http://ip30.eti.uva.nl/BIS/flora.php?selected=beschrijving&menuentry=soorten&id=2026 Fallopia sachalinensis]Huxley, A., ed. (1992). New RHS Dictionary of Gardening. Macmillan {{ISBN|0-333-47494-5}}.{{page needed|date=May 2012}}
Cultivation and uses
The shoots are tender and edible. It was introduced to Europe and grown in many botanic gardens. It came prominently into notice about 1893, when a drought in western Europe caused a decided shortage in forage for cattle. This plant was little affected, and since its tender shoots and leaves were eaten by stock, the plant was widely grown experimentally as a forage crop. It has proved less useful than was predicted, and its deliberate cultivation has been almost entirely abandoned.New International Encyclopedia. Yale University Press, 1926.{{page needed|date=May 2012}} It has, however, like F. japonica, proved to be an invasive weed in several areas.{{cite book |last1=Sukopp |first1=Herbert |first2=Uwe |last2=Starfinger |year=1995 |chapter=Reynoutria sachalinensis in Europe and in the Far East: A comparison of the species' ecology in its native and adventive distribution range |pages=151–9 |editor1-first=Petr |editor1-last=Pyšek |title=Plant Invasions: General Aspects and Social Problems |publisher=SPB Academic Pub. |isbn=978-90-5103-097-6}}
It has hybridised with Reynoutria japonica in cultivation; the hybrid, Reynoutria × bohemica (Chrtek & Chrtková) J.P.Bailey, is frequently found in the British Isles and elsewhere.Japanese Knotweed Alliance: [http://www.cabi.org/japaneseknotweedalliance/default.aspx?site=139&page=360 Fallopia hybrids] {{Webarchive|url=https://web.archive.org/web/20091009145031/http://www.cabi.org/japaneseknotweedalliance/default.aspx?site=139&page=360 |date=2009-10-09 }}
Extracts of this plant can be used as plant protectants for certain fungal and bacterial diseases.{{Cite web|url=http://www.cdms.net/ldat/ld9K4019.pdf|title=Regalia Biofungicide chemical label|last=|first=|date=|website=|access-date=}}{{Cite web|url=http://www.epa.gov/pesticides/biopesticides/ingredients/factsheets/factsheet_055809.htm|title=Reynoutria sachalinensis (Giant Knotweed) (055809) Fact Sheet {{!}} Pesticides {{!}} US EPA|date=2011-09-09|access-date=2017-02-17|url-status=bot: unknown|archive-url=https://web.archive.org/web/20110909070617/http://www.epa.gov/pesticides/biopesticides/ingredients/factsheets/factsheet_055809.htm|archive-date=2011-09-09}}
Rhizome of R. sachalinensis is the source of lactoperoxidase peroxidation cycle substrates, which can act as activators and inhibitors of the antimicrobial properties of that system.{{Cite journal |last1=Magacz |first1=Marcin |last2=Oszajca |first2=Maria |last3=Nawrot-Hadzik |first3=Izabela |last4=Drożdż |first4=Ryszard |last5=Jurczak |first5=Anna |last6=Hadzik |first6=Jakub |last7=Smakosz |first7=Aleksander |last8=Krzyściak |first8=Wirginia |date=2021 |title=Phenolic Compounds of Reynoutria sp. as Modulators of Oral Cavity Lactoperoxidase System |journal=Antioxidants |language=en |volume=10 |issue=5 |pages=676 |doi=10.3390/antiox10050676 |doi-access=free |issn=2076-3921 |pmc=8146912 |pmid=33926051}}
The species has been cultivated as an energy crop for biomass production, particularly in Germany in its commercial variety 'Igniscum', and it has shown a high productivity even in Northern latitudes, reaching a dry matter yield from {{convert|5.4 to 27.8|adj=pre|MT/ha|ST/acre|oven dry}}, annually.{{cite journal |last1=Papamatthaiakis |first1=Nikolaos |last2=Laine |first2=Antti |last3=Haapala |first3=Antti |last4=Ikonen |first4=Risto |last5=Kuittinen |first5=Suvi |last6=Pappinen |first6=Ari |last7=Kolström |first7=Marja |last8=Mola-Yudego |first8=Blas |title=New energy crop alternatives for Northern Europe: Yield, chemical and physical properties of Giant knotweed (Fallopia sachalinensis var. 'Igniscum') and Virginia mallow (Sida hermaphrodita) |journal=Fuel |date=2021 |volume=304 |page=121349 |doi=10.1016/j.fuel.2021.121349|doi-access=free |bibcode=2021Fuel..30421349P }}
References
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