''Reynoutria sachalinensis'' (giant knotweed or Sakhalin knotweed

Japanese Japanese may refer to: * Something from or related to Japan, an island country in East Asia * Japanese language, spoken mainly in Japan * Japanese people, the ethnic group that identifies with Japan through ancestry or culture ** Japanese diaspor ...

オオイタドリ ''ooitadori'',

Russian Russian(s) refers to anything related to Russia, including: *Russians (, ''russkiye''), an ethnic group of the East Slavic peoples, primarily living in Russia and neighboring countries *Rossiyane (), Russian language term for all citizens and peo ...

Горец сахалинский, Гречиха сахалинская; syns. ''Polygonum sachalinense'', ''Fallopia sachalinensis'') is a species of ''

Fallopia ''Fallopia'' is a genus of about 12 species of flowering plants in the buckwheat family, often included in a wider treatment of the related genus ''Polygonum'' in the past, and previously including '' Reynoutria''. The genus is native to temperat ...

'' native to northeastern

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

in northern Japan ( Hokkaidō, Honshū) and the far east of

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...

(

Sakhalin Sakhalin ( rus, Сахали́н, r=Sakhalín, p=səxɐˈlʲin; ja, 樺太 ''Karafuto''; zh, c=, p=Kùyèdǎo, s=库页岛, t=庫頁島; Manchu: ᠰᠠᡥᠠᠯᡳᠶᠠᠨ, ''Sahaliyan''; Orok: Бугата на̄, ''Bugata nā''; Nivkh ...

and the southern

Kurile Islands The Kuril Islands or Kurile Islands (; rus, Кури́льские острова́, r=Kuril'skiye ostrova, p=kʊˈrʲilʲskʲɪjə ɐstrɐˈva; Japanese: or ) are a volcanic archipelago currently administered as part of Sakhalin Oblast in the ...

). ''Reynoutria sachalinensis'' is a herbaceous

perennial plant A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

growing to tall, with strong, extensively spreading rhizomes forming large

clonal colonies A clonal colony or genet is a group of genetically identical individuals, such as plants, fungi, or bacteria, that have grown in a given location, all originating vegetatively, not sexually, from a single ancestor. In plants, an individual in s ...

. The leaves are some of the largest in the family, up to long and broad, nearly heart-shaped, with a somewhat wavy, crenate margin. The

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s are small, produced on short, dense panicles up to long in late summer or early autumn; it is

gynodioecious Gynodioecy is a rare breeding system that is found in certain flowering plant species in which female and hermaphroditic plants coexist within a population. Gynodioecy is the evolutionary intermediate between hermaphroditism (exhibiting both fema ...

, with male and female (male sterile) flowers on separate plants. The species is closely related to the Japanese knotweed, ''

Reynoutria japonica ''Reynoutria japonica'', synonyms ''Fallopia japonica'' and ''Polygonum cuspidatum'', is a species of herbaceous perennial plant in the knotweed and buckwheat family Polygonaceae. Common names include Japanese knotweed and Asian knotweed. It is ...

'', 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 A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...

count of 2n=44.Flora of NW Europe
''Fallopia sachalinensis''
/ref>Huxley, A., ed. (1992). ''New RHS Dictionary of Gardening''. Macmillan .

Cultivation and uses

The

shoot In botany, a plant shoot consists of any plant stem together with its appendages, leaves and lateral buds, flowering stems, and flower buds. The new growth from seed germination that grows upward is a shoot where leaves will develop. In the sp ...

s are tender and edible. It was introduced to

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...

and grown in many botanic gardens. It came prominently into notice about 1893, when a

drought A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

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. It has, however, like ''F. japonica'', proved to be an

invasive weed An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

in several areas. It has hybridised with ''Reynoutria japonica'' in cultivation; the hybrid, ''

Reynoutria × bohemica Bohemian knotweed is a nothospecies that is a cross between Japanese knotweed and giant knotweed. It has been documented as occurring in the wild in Japan. The scientific name is accepted to be ''Reynoutria'' × ''bohemica'', but it may also be ...

'' (Chrtek & Chrtková) J.P.Bailey, is frequently found in the British Isles and elsewhere.Japanese Knotweed Alliance
''Fallopia'' hybrids
/ref> Extracts of this plant can be used as plant protectants for certain fungal and bacterial diseases. 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 , annually

References

{{Taxonbar, from1=Q28922301, from2=Q2210394 Polygonoideae Flora of Japan Plants described in 1859 Edible plants Forages Stem vegetables Flora of the Russian Far East