Cirsium muticumMichx.

swamp thistle

WFO wfo-0000006887 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h

Cirsium muticum, photographed by Michael J. Papay
fig. a Michael J. Papay, CC BY 4.0 / 2021-10-11 / obs. 163073566
Cirsium muticum, photographed by Skyler Principe
fig. b Skyler Principe, CC BY 4.0 / obs. 152524881
Cirsium muticum, photographed by Mary Krieger
fig. c Mary Krieger, CC BY 4.0 / obs. 201227027
Cirsium muticum, photographed by botanygirl
fig. d botanygirl, CC BY 4.0 / obs. 159489482
Cirsium muticum, photographed by Jacob Friend
fig. e Jacob Friend, CC0 1.0 / obs. 156691647
Cirsium muticum, photographed by Mary Krieger
fig. f Mary Krieger, CC BY 4.0 / obs. 164144569
Cirsium muticum, photographed by Mary Krieger
fig. g Mary Krieger, CC BY 4.0 / obs. 156679273
Cirsium muticum, photographed by Rob Foster
fig. h Rob Foster, CC BY 4.0 / obs. 155004693

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.

Flowering n = 482 observations

Peak flowering in Aug, from 482 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 18 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.

  • Carduus muticus Pers.
  • Carduus muticus var. albiflorus Farw.
  • Carduus muticus var. muticus
  • Carduus muticus var. subpinnatifidus Britton
  • Cirsium bigelowii DC.
  • Cirsium muticum f. lactiflorum Fernald
  • Cirsium muticum f. monticola (Fernald) B.Boivin
  • Cirsium muticum f. muticum
  • Cirsium muticum var. monticola Fernald
  • Cirsium muticum var. muticum
  • Cirsium muticum var. subpinnatifidum Fernald
  • Cnicus glaber Nutt.
  • Cnicus glutinosus Bigelow
  • Cnicus muticus Elliott
  • Cnicus muticus (Michx.) Pursh
  • Cnicus muticus var. alpicola Britton & A.Br.
  • Cnicus muticus var. monticola Fernald
  • Cnicus muticus var. muticus

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.