Flora of North America species comparison

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Cirsium palustre

Cirsium helenioides

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

melancholy thistle
Habit Biennials or monocarpic perennials, 30–200(–300) cm; clusters of fibrous roots. Perennials, 40–120 cm; runner roots.
Stems

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

branches 0–few, ascending, (short).

single, erect, ± arachnoid-tomentose;

branches 0 or few, 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.

oblong to broadly lanceolate, 20–40 × 4–8 cm, finely spinulose-dentate or proximal cauline pinnatifid, lobes undivided, finely spinulose-dentate, main spines 1–2 mm, abaxial faces white-tomentose (with non-septate trichomes), adaxial glabrous;

basal present at flowering, petiolate, bases tapered;

cauline sessile, reduced distally, bases clasping, not decurrent;

distal (few, well separated), oblong or linear, the uppermost reduced to linear bracts.
Peduncles

0–1 cm.

2–10(–30) cm (elevated above distal leaves).
Involucres

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

broadly ovoid, 2–3 × 2–3.5 cm, glabrous or loosely arachnoid.
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.

red-purple, 25–30 mm, tubes 10–23 mm, throats 8–14 mm (noticeably wider than tubes), lobes 7–10 mm;

style tips 4–5 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 8–10 series, imbricate, green, ovate or lanceolate (outer) to linear-lanceolate (inner), abaxial faces with a prominent elongate glutinous ridge, outer and middle tightly appressed, margins entire, apices with ascending, weak spines 0–1 mm;

apices of inner phyllaries attenuate, flat.
Heads

few–many in dense clusters at branch tips.

borne singly or less commonly 2–5 in terminal clusters.
Cypselae

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

pappi 9–11 mm.

light brown, 3–5 mm, bodies and apical collars concolorous;

pappi 20–30 mm.
2n

= 34.

= 34.

Cirsium palustre

Cirsium helenioides
Phenology Flowering summer (Jul–Aug). Flowering summer (Jul–Aug).
Habitat Marshes, wet forests Fjordlands
Elevation 10–800 m (0–2600 ft) 0–50 m (0–200 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 USDA
Greenland; Iceland; Europe; Asia
[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 helenioides is one of only two species of the genus that have native populations in the Old World and the flora area. Neither reaches the North American mainland.

The conservation status of Cirsium helenioides is not known; it is known in the flora area only from a single fjord and possibly should be considered of conservation concern.

of conservation concern

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 19, p. 110. FNA vol. 19, p. 110.
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. 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. 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
Synonyms Carduus palustris Carduus helenioides, C. heterophyllum
Name authority (Linnaeus) Scopoli: Fl. Carniol. ed. 2, 2: 128. (1772) (Linnaeus) Hill: Hort. Kew., 64. (1768)
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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