Data sources

Each value Trefle shows for Polygonum douglasii, 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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Sourced2 Differs from sources1 Source not recorded9 Not on the record2 Sources: TRY Plant Trait Database, Earlier Trefle data

Field	Shown	What the sources say
Core
Author	Greene	No source recorded	Source not recorded
Bibliography	Bull. Calif. Acad. Sci. 1(2-4):125. 1885	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	1885	No source recorded	Source not recorded
Descriptive
Common name	Douglas's knotweed	No source recorded	Source not recorded
Observations	Canada to NW. Mexico	No source recorded	Source not recorded
Morphology
Average height	13 cm	12.5 cm · TRY Plant Trait Database · Measured · 19 observations · 2026-10-09 TRY 7.0 datasets 193	Differs from sources
Growth habit	Forb/herb	Forb/herb · Earlier Trefle data · Reported · 2026-10-19 value present before provenance tracking (2022 import), no source recorded	Sourced
Vegetable	false	No source recorded	Source not recorded
Phenology
Duration	empty	annual · TRY Plant Trait Database · Measured · 1 observation · 2026-10-09 TRY 7.0 datasets 193	Not on the record
Ecology
Nitrogen fixation	None	None · TRY Plant Trait Database · Measured · 3 observations · 2026-10-09 TRY 7.0 datasets 193, 444	Sourced
Usda legacy
C n ratio	empty	22.8 · TRY Plant Trait Database · Measured · 6 observations · 2026-10-09 TRY 7.0 datasets 193, 412	Not on the record

Polygonum douglasii Greene, 1885 14% complete

Douglas's knotweed

.fa-secondary{opacity:.4} Data sources

Data sources