Cirsium palustre
Cirsium barnebyi
cirse ou chardon des marais, European Marsh thistle, European swamp or marsh thistle, European swamp thistle, marsh thistle
Barneby's thistle
single, erect, villous to tomentose with jointed trichomes, distally tomentose with fine, unbranched trichomes;
branches 0–few, ascending, (short).
1–few, erect, gray-tomentose or glabrate;
branches few, above middle, ascending.
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-elliptic, 10–35 × 2–7 cm, strongly undulate, margins shallowly to deeply lobed, lobes 8–15 pairs, linear-lanceolate to broadly triangular, closely spaced, spreading, coarsely spinose-dentate or cleft into 2–5 spine-tipped divisions, main spines 3–5 mm, faces densely gray-white-tomentose;
basal usually present at flowering, winged-petiolate;
principal cauline becoming sessile and progressively reduced distally, bases decurrent as spiny wings to 5 cm;
distal cauline usually much reduced, less lobed.
0–1 cm.
0–4 cm.
ovoid to campanulate, 1–1.5 × 0.8–1.3 cm, thinly cobwebby tomentose with fine unbranched trichomes.
ovoid to hemispheric or campanulate, 1.7–2 × 1.5–2 cm, loosely arachnoid on phyllary margins or glabrate.
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.
lavender to pink-purple, 18–28 mm, tubes 7–9 mm, throats 4–8 mm, lobes 5–11 mm;
style tips 3.5–5 mm.
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 6–9 series, imbricate, ovate (outer) to linear-lanceolate (inner), entire, abaxial faces with narrow glutinous ridge;
outer and middle appressed, spines ascending to spreading, stramineous, 2–7 mm;
apices of inner often flexuous, narrow, flat, entire, spineless, glabrous.
few–many in dense clusters at branch tips.
1–20+, borne singly or clustered at branch tips, in leafy, ± corymbiform arrays.
tan to stramineous, 2.5–3.5 mm, apical collars 0.1–0.2 mm, shiny;
pappi 9–11 mm.
tan to brown, 5–5.5 mm, apical collars colored like body, narrow;
pappi 15–23 mm.
= 34.
Cirsium palustre
Cirsium barnebyi
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.)
Of conservation concern.
Cirsium barnebyi occurs from the southern Rocky Mountains of southwestern Wyoming, northeastern Utah, and northwestern Colorado.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
BC
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MI Flora
PNW Herbaria
WildflowerSearch
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