Data sources

Each value Trefle shows for Quercus 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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Sourced12 Source not recorded10 Not on the record7 Sources: TRY Plant Trait Database, Earlier Trefle data

Field	Shown	What the sources say
Core
Author	Hook. & Arn.	No source recorded	Source not recorded
Bibliography	Bot. Beechey Voy.: 391 (1840)	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	1840	No source recorded	Source not recorded
Descriptive
Common name	Blue oak	No source recorded	Source not recorded
Observations	California	No source recorded	Source not recorded
Morphology
Average height	800 cm	800 cm · TRY Plant Trait Database · Measured · 49 observations · 2026-10-09 TRY 7.0 datasets 28, 55, 68, 92, 184, 818, 873	Sourced
Flower color	empty	yellow · TRY Plant Trait Database · Measured · 1 observation · 2026-10-09 TRY 7.0 datasets 92	Not on the record
Flower conspicuous	false	No source recorded	Source not recorded
Foliage color	empty	green, grey · TRY Plant Trait Database · Measured · 1 observation · 2026-10-09 TRY 7.0 datasets 92	Not on the record
Foliage texture	coarse	coarse · TRY Plant Trait Database · Measured · 1 observation · 2026-10-09 TRY 7.0 datasets 92	Sourced
Fruit color	empty	brown · TRY Plant Trait Database · Measured · 1 observation · 2026-10-09 TRY 7.0 datasets 92	Not on the record
Fruit conspicuous	true	true · Earlier Trefle data · Reported · 2026-10-19 value present before provenance tracking (2022 import), no source recorded	Sourced
Growth form	Single Stem	Single Stem · Earlier Trefle data · Reported · 2026-10-19 value present before provenance tracking (2022 import), no source recorded	Sourced
Growth habit	Tree	Tree · Earlier Trefle data · Reported · 2026-10-19 value present before provenance tracking (2022 import), no source recorded	Sourced
Growth rate	Slow	Slow · TRY Plant Trait Database · Measured · 1 observation · 2026-10-09 TRY 7.0 datasets 92	Sourced
Maximum height	2435 cm	2435 cm · TRY Plant Trait Database · Measured · 2 observations · 2026-10-09 TRY 7.0 datasets 28, 55, 68, 92, 184, 818, 873	Sourced
Vegetable	false	No source recorded	Source not recorded
Phenology
Duration	perennial	perennial · TRY Plant Trait Database · Measured · 8 observations · 2026-10-09 TRY 7.0 datasets 28, 92, 759, 818	Sourced
Ecology
Nitrogen fixation	None	None · TRY Plant Trait Database · Measured · 5 observations · 2026-10-09 TRY 7.0 datasets 20, 55, 57, 444	Sourced
Ph maximum	pH 7.5	pH 7.5 · Earlier Trefle data · Reported · 2026-10-19 value present before provenance tracking (2022 import), no source recorded	Sourced
Ph minimum	pH 4.5	pH 4.5 · Earlier Trefle data · Reported · 2026-10-19 value present before provenance tracking (2022 import), no source recorded	Sourced
Cultivation
Minimum root depth	150 cm	150 cm · TRY Plant Trait Database · Measured · 5 observations · 2026-10-09 TRY 7.0 datasets 92, 432, 818	Sourced
Usda legacy
C n ratio	empty	24.3 · TRY Plant Trait Database · Measured · 58 observations · 2026-10-09 TRY 7.0 datasets 412, 981	Not on the record
Other
Human usage type	—	fuelwood, posts · TRY Plant Trait Database · Reported · 1 observation · 2026-10-09 TRY 7.0 datasets 92	Not on the record
Salt tolerance	—	None · TRY Plant Trait Database · Measured · 1 observation · 2026-10-09 TRY 7.0 datasets 92	Not on the record
Shade tolerance	—	None · TRY Plant Trait Database · Measured · 1 observation · 2026-10-09 TRY 7.0 datasets 92	Not on the record

Quercus douglasii Hook. & Arn., 1840 35% complete

Blue oak

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

Data sources