Data sources

Each value Trefle shows for Reynoutria japonica, with what every source says about it. When sources disagree, the strongest source is shown (how sources are ranked). Values imported before sources were recorded one by one are marked Source not recorded.

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Sourced16 Differs from sources1 Source not recorded9 Not on the record6 Sources: TRY Plant Trait Database, Earlier Trefle data

Field	Shown	What the sources say
Core
Author	Houtt.	No source recorded	Source not recorded
Bibliography	Nat. Hist. 2(8): 640 (1777)	No source recorded	Source not recorded
Phylum	Tracheophyta	No source recorded	Source not recorded
Rank	species	No source recorded	Source not recorded
Status	accepted	No source recorded	Source not recorded
Year	1777	No source recorded	Source not recorded
Descriptive
Common name	Japanese knotweed	No source recorded	Source not recorded
Observations	Russian Far East to China and Temp. E. Asia	No source recorded	Source not recorded
Morphology
Average height	165 cm	164.6 cm · TRY Plant Trait Database · Measured · 9 observations · 2026-10-09 TRY 7.0 datasets 25, 28, 90, 164, 178, 251, 500, 882	Differs from sources
Biological type	geophyte	geophyte · TRY Plant Trait Database · Measured · 14 observations · 2026-10-09 TRY 7.0 datasets 4, 25, 71, 164, 174, 178, 500, 918	Sourced
Flower color	white	white · TRY Plant Trait Database · Measured · 3 observations · 2026-10-09 TRY 7.0 datasets 4, 882	Sourced
Foliage texture	fine	fine · TRY Plant Trait Database · Measured · 2 observations · 2026-10-09 TRY 7.0 datasets 4, 71	Sourced
Fruit color	brown, black	black, brown · TRY Plant Trait Database · Measured · 2 observations · 2026-10-09 TRY 7.0 datasets 882	Sourced
Fruit shape	nut	nut · TRY Plant Trait Database · Measured · 2 observations · 2026-10-09 TRY 7.0 datasets 4, 882	Sourced
Maximum height	225 cm	225 cm · TRY Plant Trait Database · Measured · 4 observations · 2026-10-09 TRY 7.0 datasets 25, 28, 90, 164, 178, 251, 500, 882	Sourced
Sexuality	empty	gynodioecious · TRY Plant Trait Database · Measured · 1 observation · 2026-10-09 TRY 7.0 datasets 4	Not on the record
Vegetable	false	No source recorded	Source not recorded
Phenology
Bloom months	jul, aug	jul, aug · TRY Plant Trait Database · Measured · 4 observations · 2026-10-20 TRY 7.0 datasets 4, 174 1 earlier or rejected value Superseded feb, jul · TRY Plant Trait Database · Measured · 4 observations · 2026-10-09 TRY 7.0 datasets 4, 174	Sourced
Duration	perennial	perennial · TRY Plant Trait Database · Measured · 12 observations · 2026-10-09 TRY 7.0 datasets 4, 25, 71, 164, 178, 460, 882, 918	Sourced
Ecology
Atmospheric humidity	5 / 9 · medium air humidity	5 / 9 · medium air humidity · Earlier Trefle data · Reported · 2026-10-19 value present before provenance tracking (2022 import), no source recorded	Sourced
Ground humidity	7 / 12 · wet, flooded a few weeks a year (hygrophilous)	7 / 12 · wet, flooded a few weeks a year (hygrophilous) · TRY Plant Trait Database · Measured · 2 observations · 2026-10-09 TRY 7.0 datasets 178, 489	Sourced
Light	7 / 9 · half-light to light	7 / 9 · half-light to light · TRY Plant Trait Database · Measured · 3 observations · 2026-10-09 TRY 7.0 datasets 178, 489	Sourced
Nitrogen fixation	None	None · TRY Plant Trait Database · Measured · 2 observations · 2026-10-09 TRY 7.0 datasets 71	Sourced
Ph maximum	pH 6.5	pH 6.5 · Earlier Trefle data · Inferred · 2026-10-19 value present before provenance tracking (2022 import), no source recorded derived from a Baseflor soil reaction class by the 2022 import, a class not a measurement	Sourced
Ph minimum	pH 5.5	pH 5.5 · Earlier Trefle data · Inferred · 2026-10-19 value present before provenance tracking (2022 import), no source recorded derived from a Baseflor soil reaction class by the 2022 import, a class not a measurement	Sourced
Soil nutriments	8 / 9 · very rich (pereutrophic)	8 / 9 · very rich (pereutrophic) · TRY Plant Trait Database · Measured · 4 observations · 2026-10-09 TRY 7.0 datasets 178, 242, 489	Sourced
Soil salinity	0 / 9 · absent from saline soils	0 / 9 · absent from saline soils · TRY Plant Trait Database · Measured · 4 observations · 2026-10-09 TRY 7.0 datasets 178, 242, 489	Sourced
Usda legacy
C n ratio	empty	21.8 · TRY Plant Trait Database · Measured · 6 observations · 2026-10-09 TRY 7.0 datasets 90, 228	Not on the record
Other
Propagation method	—	vegetative · TRY Plant Trait Database · Measured · 3 observations · 2026-10-09 TRY 7.0 datasets 174	Not on the record
Shade tolerance	—	Light · TRY Plant Trait Database · Measured · 3 observations · 2026-10-09 TRY 7.0 datasets 174	Not on the record
Soil ph indicator	—	6 · TRY Plant Trait Database · Measured · 3 observations · 2026-10-09 TRY 7.0 datasets 178, 242, 489	Not on the record
Temperature indicator	—	5 · TRY Plant Trait Database · Measured · 3 observations · 2026-10-09 TRY 7.0 datasets 242, 489	Not on the record

Reynoutria japonica Houtt., 1777 43% complete

Japanese knotweed

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Data sources