Alnus rubraBong.

Red Alder

WFO wfo-0000947467 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h

Alnus rubra, photographed by Ellyne Geurts
fig. a Ellyne Geurts, CC0 1.0 / 2022-05-02 / obs. 195425182
Alnus rubra, photographed by Lyrae
fig. b Lyrae, CC BY 4.0 / obs. 198646722
Alnus rubra, photographed by Garth Harwood
fig. c Garth Harwood, CC BY 4.0 / obs. 193976752
Alnus rubra, photographed by Randal
fig. d Randal, CC0 1.0 / obs. 183151676
Alnus rubra, photographed by giantcicada
fig. e giantcicada, CC BY 4.0 / obs. 184004469
Alnus rubra, photographed by John A Haskins
fig. f John A Haskins, CC BY 4.0 / obs. 182031522
Alnus rubra, photographed by Lyrae
fig. g Lyrae, CC BY 4.0 / obs. 198769441
Alnus rubra, photographed by Jens-Christian Svenning
fig. h Jens-Christian Svenning, CC BY 4.0 / obs. 202867802

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 = 155 observations

Peak flowering in Mar, from 155 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 5 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.

  • Alnus incana var. rubra (Bong.) Regel
  • Alnus oregana Nutt.
  • Alnus rubra f. pinnatisecta (Starker) Rehder
  • Alnus rubra var. pinnatisecta Starker
  • Alnus rubra var. rubra

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.