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

Beaumont thistle, yellowspine thistle

Habit Biennials or monocarpic perennials, 30–200(–300) cm; clusters of fibrous roots. Perennials, 30–90 cm; crown sprouts or runner roots producing adventitious buds.
Stems

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

branches 0–few, ascending, (short).

1–20+, erect or ascending, densely gray-tomentose with non-septate trichomes;

branches 0 or few, usually in distal 1/2, ascending.

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 oblong to narrowly elliptic, 10–30 × 2–8 cm, strongly undulate, margins coarsely dentate or shallowly to deeply pinnatifid with 8–15 pairs of lobes 0.5–2 cm, often revolute, lobes ± triangular, closely spaced, spreading, spinose-dentate and cleft into 2–5 spine-tipped divisions, main spines 5–20 mm, yellowish, abaxial faces densely white-tomentose, adaxial thinly gray-tomentose;

basal usually present at flowering, winged-petiolate;

principal cauline sessile, progressively reduced distally, bases ± auriculate to long-decurrent as spiny wings;

distal cauline usually much reduced, less lobed.

Peduncles

0–1 cm.

0–4 cm.

Involucres

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

ovoid to hemispheric or broadly campanulate, 2.5–4.5 × 2.5–4.5 cm in first-formed heads, often smaller in later ones, 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.

white or pale lavender to purple, pink, or red, 25–45 mm, tubes 8–25 mm, throats 6–17 mm, lobes 6–15 mm;

style tips 2–8 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 5–10 series, imbricate, ovate (outer) to linear-lanceolate (inner), margins entire, abaxial faces with narrow glutinous ridge;

outer and middle appressed, spines spreading, 3–12 mm;

apices of inner often flexuous, expanded and flat, scabrid-margined, sometimes erose, spineless.

Heads

few–many in dense clusters at branch tips.

1–few, in leafy, ± 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 lighter or darker streaks, 6–9 mm, apical collars colored like the body, narrow;

pappi (white or tawny), 20–40 mm, usually noticeably shorter than corolla.

2n

= 34.

= 30, 31, 32, 34.

Cirsium palustre

Cirsium ochrocentrum

Phenology Flowering summer (Jul–Aug).
Habitat Marshes, wet forests
Elevation 10–800 m (0–2600 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
AZ; CA; CO; KS; NE; NM; OK; SD; TX; UT; WY; n Mexico
[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.)

Varieties 2 (2 in the flora).

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

Key
1. Stems densely leafy, nodes crowded; leaves often long- decurrent; corollas white or pale lavender to purple
var. ochrocentrum
1. Stems leafy, nodes usually well separated; distal cauline leaves clasping, or if decurrent spiny wing usually less than 1 cm; corollas red, pink, or reddish purple (rarely white)
var. martinii
Source FNA vol. 19, p. 110. FNA vol. 19, p. 123.
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. ownbeyi, C. palustre, 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
Subordinate taxa
C. ochrocentrum var. martinii, C. ochrocentrum var. ochrocentrum
Synonyms Carduus palustris
Name authority (Linnaeus) Scopoli: Fl. Carniol. ed. 2, 2: 128. (1772) A. Gray: Mem. Amer. Acad. Arts, n. s. 4: 110. (1849)
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