Flora of North America species comparison

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Cirsium palustre

Cirsium pitcheri

cirse ou chardon des marais, European Marsh thistle, European swamp or marsh thistle, European swamp thistle, marsh thistle

dune thistle, Pitcher's thistle, sand-dune thistle
Habit Biennials or monocarpic perennials, 30–200(–300) cm; clusters of fibrous roots. Biennials or short-lived monocarpic perennials, 20–100 cm; taproots long.
Stems

single, erect, villous to tomentose with jointed trichomes, distally tomentose with fine, unbranched trichomes;

branches 0–few, ascending, (short).

1 or few, erect, densely gray-tomentose;

branches 0 to several, ascending to spreading.
Leaves

blades narrowly elliptic to oblanceolate, 15–30+ × 3–10 cm, margins shallowly to very deeply pinnatifid, narrow lobes separated by broad sinuses, spiny-dentate to lobed, main spines 2–6 mm, abaxial villous to tomentose with jointed trichomes, sometimes also thinly tomentose with fine unbranched trichomes, adaxial faces villous with septate trichomes or glabrate;

basal often present at flowering, petioles spiny-winged, bases tapered;

cauline many, sessile, gradually reduced and becoming widely spaced above, bases long-decurrent with prominently spiny wings;

distal cauline deeply pinnatifid with few-toothed spine-tipped lobes.

blades elliptic to obovate, 10–30 × 8–14 cm, deeply divided nearly to midveins, lobes ascending to spreading, linear, remote, margins revolute, entire or minutely spinulose, main spines 1–2 mm, faces gray-tomentose, more densely so abaxially;

basal present or withered at flowering, petiolate;

principal cauline well distributed, bases decurrent as linear-lobed to spiny wings 1–3 cm;

distal cauline well developed.
Peduncles

0–1 cm.

0–5 cm.
Involucres

ovoid to campanulate, 1–1.5 × 0.8–1.3 cm, thinly cobwebby tomentose with fine unbranched trichomes.

ovoid to campanulate, 2–3 × 2–3 cm, loosely arachnoid on phyllary margins or glabrate.
Corollas

lavender to purple (white), 11–13 mm, tubes 5–7 mm, throats 2–3 mm, lobes 3–4.5 mm;

style tips 1.5–2 mm.

dull white or pinkish-tinged (rarely rich purple), 20–30 mm, tubes 8.5–15 mm, throats 4.5–10 mm, lobes 3–8 mm;

style tips 3.5–5.5 mm.
Phyllaries

in 5–7 series, strongly imbricate, greenish, or with purplish tinge, lanceolate to ovate (outer) or linear-lanceolate (inner), margins thinly arachnoid-ciliate, abaxial faces with narrow glutinous ridge, outer and middle appressed, entire, apices acute, mucronate or spines erect or spreading, weak, 0.3–1 mm;

apices of inner phyllaries purplish, linear-attenuate, scarious, flat.

in 6–8 series, imbricate, ovate-lanceolate (outer) to linear-lanceolate (inner), abaxial faces with narrow glutinous ridge;

outer and middle appressed, acute, spines ascending to spreading, slender, 1–2(–3) mm;

apices of inner often flexuous, flattened, spineless, scabrid.
Heads

few–many in dense clusters at branch tips.

1–20+ in corymbiform arrays.
Cypselae

tan to stramineous, 2.5–3.5 mm, apical collars 0.1–0.2 mm, shiny;

pappi 9–11 mm.

light brown, sometimes with darker streaks, 6–7.5 mm, apical collars lighter colored, very narrow;

pappi 15–30 mm, usually noticeably shorter than corolla.
2n

= 34.

= 34.

Cirsium palustre

Cirsium pitcheri
Phenology Flowering summer (Jul–Aug). Flowering spring–summer (May–Sep).
Habitat Marshes, wet forests Sand dunes and beaches
Elevation 10–800 m (0–2600 ft) 180–200 m (600–700 ft)
Distribution
from FNA
MA; MI; NH; NY; WI; BC; NF; NS; ON; QC; SPM; Europe [Introduced in North America]
[WildflowerSearch map]
[BONAP county map]
from FNA
IL; IN; MI; WI; ON
[WildflowerSearch map]
[BONAP county map]
Discussion

Cirsium palustre is a noxious weed, native to Europe, that invasively spreads through wetland communities, forming impenetrable spiny stands as it displaces native species. The range of this pernicious weed in North America is rapidly expanding. It has the potential to spread into boreal forest areas across the continent; in Europe it grows nearly to the Arctic Circle. The rapid spread of C. palustre in Michigan (E. G. Voss 1972–1996, vol. 3) is indicative of its invasiveness. Spontaneous hybrids between C. palustre and C. arvense have been reported from England and other European countries (W. A. Sledge 1975) and can be expected wherever these species grow together in North America.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Cirsium pitcheri is endemic to beach and dune habitats around lakes Huron, Michigan, and Superior. It has been extirpated from portions of its former range at the southern end of Lake Michigan. It is threatened by foot traffic, off-road vehicular activity, and clearing and development of beachside habitats. It is in the Center for Plant Conservation’s National Collection of Endangered Plants.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 19, p. 110. FNA vol. 19, p. 122.
Parent taxa Asteraceae > tribe Cardueae > Cirsium Asteraceae > tribe Cardueae > Cirsium
Sibling taxa
C. altissimum, C. andersonii, C. andrewsii, C. arizonicum, C. arvense, C. barnebyi, C. brevifolium, C. brevistylum, C. canescens, C. carolinianum, C. ciliolatum, C. clavatum, C. crassicaule, C. cymosum, C. discolor, C. douglasii, C. drummondii, C. eatonii, C. edule, C. engelmannii, C. flodmanii, C. foliosum, C. fontinale, C. grahamii, C. helenioides, C. hookerianum, C. horridulum, C. hydrophilum, C. inamoenum, C. joannae, C. kamtschaticum, C. lecontei, C. longistylum, C. mohavense, C. muticum, C. neomexicanum, C. nuttallii, C. occidentale, C. ochrocentrum, C. ownbeyi, C. parryi, C. perplexans, C. pitcheri, C. praeteriens, C. pulcherrimum, C. pumilum, C. quercetorum, C. remotifolium, C. repandum, C. rhothophilum, C. rydbergii, C. scariosum, C. texanum, C. tracyi, C. turneri, C. undulatum, C. vinaceum, C. virginianum, C. vulgare, C. wheeleri, C. wrightii
C. altissimum, C. andersonii, C. andrewsii, C. arizonicum, C. arvense, C. barnebyi, C. brevifolium, C. brevistylum, C. canescens, C. carolinianum, C. ciliolatum, C. clavatum, C. crassicaule, C. cymosum, C. discolor, C. douglasii, C. drummondii, C. eatonii, C. edule, C. engelmannii, C. flodmanii, C. foliosum, C. fontinale, C. grahamii, C. helenioides, C. hookerianum, C. horridulum, C. hydrophilum, C. inamoenum, C. joannae, C. kamtschaticum, C. lecontei, C. longistylum, C. mohavense, C. muticum, C. neomexicanum, C. nuttallii, C. occidentale, C. ochrocentrum, C. ownbeyi, C. palustre, C. parryi, C. perplexans, C. praeteriens, C. pulcherrimum, C. pumilum, C. quercetorum, C. remotifolium, C. repandum, C. rhothophilum, C. rydbergii, C. scariosum, C. texanum, C. tracyi, C. turneri, C. undulatum, C. vinaceum, C. virginianum, C. vulgare, C. wheeleri, C. wrightii
Synonyms Carduus palustris Cnicus pitcheri
Name authority (Linnaeus) Scopoli: Fl. Carniol. ed. 2, 2: 128. (1772) (Torrey ex Eaton) Torrey & A. Gray: Fl. N. Amer. 2: 456. (1843)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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