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An example collection, so you can see what this page does. Nothing added here is kept: leaving deletes it.
Reynoutria compacta; photograph Bob, CC BY, iNaturalist via GBIF CC BYBob, CC BY, iNaturalist via GBIF

Reynoutria compacta (Hook.f.) Nakai

Dwarf Japanese knotweed

Polygonaceae · Japan, Korea

Cited as Kew's World Checklist cites it, Reynoutria compacta (Hook.f.) Nakai: GBIF's backbone key for this page carries the name with another author, (Hook.fil.) Nakai.

No habitat climate
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Reynoutria compacta, photograph Bob, CC BY, iNaturalist via GBIFReynoutria compacta, photograph Ryan Sorrells, CC BY, iNaturalist via GBIFReynoutria compacta, photograph Connor McInerney, CC BY, iNaturalist via GBIFReynoutria compacta, photograph msieges, CC0, iNaturalist via GBIFReynoutria compacta, photograph Марина Давлетшина, CC BY, iNaturalist via GBIFReynoutria compacta, photograph Марина Давлетшина, CC BY, iNaturalist via GBIF 24 photographs ›

Cultivation

Nothing derived: no habitat climate for this species.

Climate across the habitat

No habitat climate can be derived: Only 1 distinct land cell of the climate grid holds an in-range record placed to within 10 km; three are needed for an envelope. 8 of the 9 in-range records are placed to worse than 10 km, or to no stated accuracy and fewer than three decimals or by something other than a person's observation, and cannot place a climate cell, though they count for the map and its marker.

Natural habitat

Native range as published by WCVP; the marker is where the records are densest and decides nothing.
Openly licensed records inside the range, framed on where they fall.
NativeJapan, Korea · introduced: Denmark, Finland, Great Britain, Ireland, Norway, Sweden, Belgium, Czechoslovakia, Germany, France, South European Russia · regions are the level-3 units of the World Geographical Scheme for Recording Plant Distributions, as Kew's World Checklist records ranges, some under historical names such as Yugoslavia or Czechoslovakia (how).
Map marker36.464, 137.875 · in the densest population, 8 records (89% of those in range)
Kew's description“perennial or rhizomatous geophyte” · “temperate” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 9 georeferenced records inside the native range; the map shows only the 8 openly licensed ones, which alone would put the marker in the same place. 264 records outside the WCVP native range not used. Under a dozen records behind the map. No climate across the range is derived for this species. 8 in-range records are placed to worse than 10 km, or with no stated accuracy (admitted only as a person's observation to three decimals), and stay on the map but off the climate.
How this section is made
The map marker: the openly licensed record nearest the middle of the densest 1° population of the 9 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Reynoutria compacta, photograph 1did not loadReynoutria compacta, photograph 2did not loadReynoutria compacta, photograph 3did not loadReynoutria compacta, photograph 4did not loadReynoutria compacta, photograph 5did not loadReynoutria compacta, photograph 6did not load

Photographs: Bob, CC BY, iNaturalist via GBIF; Ryan Sorrells, CC BY, iNaturalist via GBIF; Connor McInerney, CC BY, iNaturalist via GBIF; msieges, CC0, iNaturalist via GBIF; Марина Давлетшина, CC BY, iNaturalist via GBIF (2).

Other Reynoutria 4 in the reference

Reynoutria × bohemica Reynoutria × bohemica Bohemian knotweed Photo: CC BY, E. A.Reynoutria forbesii Reynoutria forbesii Forbes’ knotweed Photo: CC BY, 鄭雪雲Reynoutria japonica Reynoutria japonica Japanese knotweed Photo: CC BY, arthur_haendlerReynoutria sachalinensis Reynoutria sachalinensis Giant knotweed Photo: CC BY, Marcin Dyderski

Names & registers

Also known as Fallopia compacta; Fallopia japonica var. compacta; Polygonum compactum; Polygonum cuspidatum f. compactum; Polygonum cuspidatum var. compactum and 3 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidata

The record

Family
Polygonaceae
Described by
(Hook.f.) Nakai
Native to
Japan, Korea
Wild records
9 in range · 8 open

Every figure here is derived from public data by a stated rule and names its source; nothing about this species is written for its page by a person or by AI, apart from the marked, credited quotations. How →

Where this page came from built 2026-10-22
GBIF species record gbif.species answeredasked 2026-10-22GBIF's key 6709291 is Reynoutria compacta (Hook.fil.) Nakai; the page links Kew's Reynoutria compacta (Hook.f.) Nakai, and the name is cited as Kew cites it
GBIF synonyms gbif.synonyms answeredasked 2026-10-22
GBIF common names gbif.vernacular answeredasked 2026-10-22names fetched 2026-10-22
WCVP native range wcvp.distribution answeredas of 2026-06-04
GBIF occurrence records gbif.occurrences answeredas of 2026-10-21GBIF occurrence download https://doi.org/10.15468/dl.hbdw64, of 2026-10-21; 28 records within 1 km of a botanic garden, herbarium or zoo left out (11 at a botanic garden or arboretum, 6 at a herbarium, 11 at a zoo; Wikidata's list)
Habitat climate climate nothing to reportasked 2026-10-22only 1 distinct land cell of the climate grid holds an in-range record placed to within 10 km; three are needed for an envelope
Wikidata wikidata answeredasked 2026-10-22found by its label; its POWO identifier 77221860-1 is Kew's for Reynoutria compacta (Hook.f.) Nakai
Wikipedia wikipedia nothing to reportasked 2026-10-22Wikipedia redirects Reynoutria compacta to Reynoutria japonica
iNaturalist taxon inat.taxon not asked
iNaturalist photographs, wild inat.photos.wild not asked
iNaturalist photographs, cultivated inat.photos.cultivated not asked
GBIF media gbif.media answeredasked 2026-10-22
OpenAlex papers openalex not askednot yet asked for this reference; a later fill takes the papers from OpenAlex's snapshot

Every source is recorded as having answered, reported nothing, refused, failed, not been asked, or answered twice where one answer is taken (“not taken: two items answered”), and, for a source asked when this page was built, when: the figures are as the source held them that day; a source read from a file (Kew's World Checklist, a GBIF download) says "as of" the file's day instead; a row carried from an earlier build of the page names that build instead. Only “nothing to report” is ever shown as an absence. Records came from 13 datasets via GBIF.org; each carries its own licence.

Cultifolio

Opening your plants…