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

Tracy's thistle

Habit Biennials or monocarpic perennials, 30–200(–300) cm; clusters of fibrous roots. Perennials, 50–200+ cm; tap-rooted.
Stems

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

branches 0–few, ascending, (short).

1–several, erect or ascending, thinly gray-tomentose or ± glabrate;

branches few to many, 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 elliptic to oblong, 8–40 × 1–12 cm, margins weakly to strongly undulate, spinose-dentate or shallowly to deeply lobed, lobes ascending to spreading, ± triangular, mostly well separated, spinulose and coarsely dentate or cleft into 2–3 lanceolate to triangular, often entire-margined, spine-tipped divisions, main spines 2.5–7+ mm, abaxial faces densely gray-tomentose, adaxial thinly tomentose;

basal sometimes present at flowering, winged-petiolate;

principal cauline becoming sessile and progressively reduced distally, widest at bases, bases ± auriculate-clasping to short-decurrent;

distal cauline reduced, often spinier.

Peduncles

0–1 cm.

0–10+ 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, 2–3 × 1.7–3.5 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.

white to lavender or pink-purple, 23–30 mm, tubes 9–14 mm, throats 5.5–10.5 mm, lobes 5.5–9.5 mm;

style tips 4–7 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 6–10 series, imbricate, ovate to lanceolate (outer) to linear-lanceolate (inner), margins entire, abaxial faces with prominent glutinous ridge;

outer and middle appressed, spines spreading, slender to stout, 2–6 mm;

apices of inner often flexuous, narrow, flat, ± entire, spineless or tipped with weak spines.

Heads

few–many in dense clusters at branch tips.

1–many, terminal on branches and often in leaf axils, 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 to dark brown, 6–7 mm, apical collars colored like body or rarely yellowish, narrow;

pappi 20–23 mm, usually noticeably shorter than corolla.

2n

= 34.

= 24.

Cirsium palustre

Cirsium tracyi

Phenology Flowering summer (Jul–Aug). Flowering late spring–summer (Jun–Aug).
Habitat Marshes, wet forests Dry slopes, sagebrush deserts, pinyon-juniper woodlands, openings in montane coniferous forests, often in disturbed areas
Elevation 10–800 m (0–2600 ft) 1400–2900 m (4600–9500 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
CO; NM; UT
[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 tracyi occurs from eastern Utah and western Colorado south in the Colorado Plateau and southern Rocky Mountains to northwestern New Mexico. Large-headed plants of Cirsium tracyi and small-headed individuals of C. undulatum are sometimes difficult to distinguish. P. L. Barlow-Irick (unpubl.) found that although there is much overlap in floral measurements of C. tracyi and C. undulatum, the means for some of these characters are statistically significant. Corolla lobes of C. tracyi, for instance, average about 7 mm and those of C. undulatum about 10 mm. The species differ in chromosome number as well.

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

Source FNA vol. 19, p. 110. FNA vol. 19, p. 121.
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. pitcheri, C. praeteriens, C. pulcherrimum, C. pumilum, C. quercetorum, C. remotifolium, C. repandum, C. rhothophilum, C. rydbergii, C. scariosum, C. texanum, C. turneri, C. undulatum, C. vinaceum, C. virginianum, C. vulgare, C. wheeleri, C. wrightii
Synonyms Carduus palustris Carduus tracyi, C. acuatum, C. floccosum, C. undulatus var. tracyi
Name authority (Linnaeus) Scopoli: Fl. Carniol. ed. 2, 2: 128. (1772) (Rydberg) Petrak: Beih. Bot. Centralbl. 35(2): 424. (1917)
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