Cirsium pitcheri (sand dune thistle)

Plate 1 figs. a–h · 8 separate observations

Cirsium pitcheri, photographed by Craig Martin — fig. a Craig Martin, CC0 1.0 / 2022-06-05 / obs. 203714004

Cirsium pitcheri, photographed by Liren Varghese — fig. b Liren Varghese, CC BY 4.0 / obs. 202754838

Cirsium pitcheri, photographed by Ethan Rose — fig. c Ethan Rose, CC BY 4.0 / obs. 199220576

Cirsium pitcheri, photographed by Paula Dreeszen — fig. d Paula Dreeszen, CC BY 4.0 / obs. 197916427

Cirsium pitcheri, photographed by William D. Leodinh — fig. f William D. Leodinh, CC BY 4.0 / obs. 127572243

Cirsium pitcheri, photographed by Forest Botial-Jarvis — fig. g Forest Botial-Jarvis, CC BY 4.0 / obs. 83781387

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.

Native range 5 botanical countries

Native distribution of Cirsium pitcheri, after Kew’s World Checklist of Vascular Plants. Introduced, extinct and doubtful records are excluded, so this is where the plant is from, not everywhere it now grows.

Region	TDWG code	Continent
Illinois	ILL	NORTHERN AMERICA
Indiana	INI
Michigan	MIC
Ontario	ONT
Wisconsin	WIS

Region boundaries approximated from Natural Earth (public domain) and mapped to TDWG World Geographical Scheme for Recording Plant Distributions (WGSRPD) level-3 botanical countries (Brummitt 2001). Indicative, not the official WGSRPD geometry.

Flowering 89 in flower of 677 examined

26%

55%

38%

Proportion of examined Cirsium pitcheri in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	0	1	too few examined
Feb	0	1	too few examined
Mar	0	0	too few examined
Apr	0	2	too few examined
May	0	72	0%	0% to 5%
Jun	47	182	26%	20% to 33%
Jul	31	56	55%	42% to 68%
Aug	10	26	38%	22% to 57%
Sep	0	28	0%	0% to 12%
Oct	1	224	0%	0% to 2%
Nov	0	85	0%	0% to 4%
Dec	0	0	too few examined

Peak flowering in Jul. Each bar is the share of Cirsium pitcheri observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 89 of 677 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 5 months have fewer than 5 examined observations, so no proportion is drawn for them. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.cgje2x.

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.

Carduus pitcheri (Torr. ex Eaton) Porter
Carduus pitcheri Steud.
Cirsium pitcheri f. magenteum E.G.Voss
Cirsium pitcheri f. pitcheri
Cnicus pitcheri Torr. ex Eaton

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.
Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.
Kew, World Checklist of Vascular Plants (WCVP v16). native distribution by TDWG level-3 botanical country, and life form. CC BY 3.0. Retrieved 2026-06-04.

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