Cirsium andersonii (Anderson's thistle)

Plate 1 figs. a–h

Cirsium andersonii, photographed by Diego Blanco — fig. a Diego Blanco, CC0 1.0 / 2021-08-13 / obs. 156175514

Cirsium andersonii, photographed by Quinn Shemet — fig. c Quinn Shemet, CC BY 4.0 / obs. 90978238

Cirsium andersonii, photographed by Steve Woodward — fig. d Steve Woodward, CC0 1.0 / obs. 91138957

Cirsium andersonii, photographed by Alan Rockefeller — fig. e Alan Rockefeller, CC BY 4.0 / obs. 89344820

Cirsium andersonii, photographed by Frances Oliver — fig. f Frances Oliver, CC BY 4.0 / obs. 85739605

Cirsium andersonii, photographed by joergmlpts — fig. g joergmlpts, CC BY 4.0 / obs. 48300345

Cirsium andersonii, photographed by Adam J. Searcy — fig. h Adam J. Searcy, CC BY 4.0 / obs. 46984521

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 = 1,319 observations

551

516

197

Flowering observations of Cirsium andersonii by month
Month	Observations
Jan	0
Feb	0
Mar	0
Apr	0
May	1
Jun	25
Jul	551
Aug	516
Sep	197
Oct	29
Nov	0
Dec	0

Peak flowering in Jul, from 1,319 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 2 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.

Cirsium andersonii Jeps.
Cnicus andersonii A.Gray

Sourcesevery claim on this page

World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
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.