Quercus douglasiiHook. & Arn.

blue oak

WFO wfo-0000290545 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h

Quercus douglasii, photographed by Amthinkia
fig. a Amthinkia, CC0 1.0 / 2022-05-23 / obs. 200433075

Every figure is a research-grade observation under CC0, CC BY or CC BY-SA, rehosted with the photographer’s name, the licence and the observation it came from. Photographs under a NonCommercial licence are excluded from this site and are never stored, which costs us a great many pictures and is not negotiable.

Confused withby our own model

These are not lookalikes we guessed at. Each one is a species our identification model genuinely mistook for this plant, and how many times. The error rate is published.

Flowering n = 104 observations

Flowering observations of Quercus douglasii by month
MonthObservations
Jan1
Feb3
Mar39
Apr44
May15
Jun0
Jul2
Aug0
Sep0
Oct0
Nov0
Dec0

Peak flowering in Apr, from 104 community-annotated observations worldwide. This is a global aggregate, not a forecast for your garden: the same species flowers on different dates in different hemispheres, and citizen-science records cluster near cities, at weekends, and in spring. Where a species has fewer than 30 annotated records we do not draw this chart at all.

Also published as 4 synonyms

A synonym is not an error. It is a record of botanists disagreeing, in print, about where this plant belongs. Each of these was somebody’s considered answer.

  • Quercus douglasii var. ransomii Zabel
  • Quercus gambelii Liebm.
  • Quercus oblongifolia var. brevilobata Torr.
  • Quercus ransomii Kellogg

Sourcesevery claim on this page

  1. World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
  2. iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.

We publish what we can source and we say so when we cannot. This page has no care advice, no toxicity claim and no native range, because we do not yet have those from a source we can cite.