Cirsium palustre
Cirsium fontinale
cirse ou chardon des marais, European Marsh thistle, European swamp or marsh thistle, European swamp thistle, marsh thistle
fountain thistle
single, erect, villous to tomentose with jointed trichomes, distally tomentose with fine, unbranched trichomes;
branches 0–few, ascending, (short).
1–several, erect, loosely arachnoid-tomentose, glandular-pilose;
branches several to many, spreading.
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 oblanceolate to oblong or elliptic, 20–70 × 5–16 cm, strongly undulate, shallowly to deeply pinnatifid, lobes coarsely toothed or with triangular secondary lobes, main spines 3–15 mm, abaxial faces more densely tomentose, adaxial densely glandular with short, multicellular trichomes and ± tomentose with fine, arachnoid, non-septate trichomes;
basal often present at flowering, petiolate;
principal cauline well distributed, becoming sessile, gradually reduced distally, bases auriculate-decurrent with broad, spiny-margined wings 3 cm or less;
distal cauline leaves progressively reduced, ± bractlike.
0–1 cm.
0–7 cm.
ovoid to campanulate, 1–1.5 × 0.8–1.3 cm, thinly cobwebby tomentose with fine unbranched trichomes.
(green to purple), hemispheric or campanulate, 1.5–3 × 2–5 cm, glabrous or puberulent.
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 pinkish or lavender, 14.5–22 mm, tubes 5–8 mm, throats 4.5–9 mm, lobes 3–8 mm;
style tips 2.5–4.5 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 6–10 series, imbricate, ovate to lanceolate, abaxial faces without glutinous ridge;
outer and mid bases appressed, short, bodies entire to erose or ciliolate (rarely outer spine-margined), apices spreading to recurved or reflexed, long, dilated, adaxially puberulent, spines 1–6 mm;
apices of inner erect or reflexed, flattened or tipped with short spines.
few–many in dense clusters at branch tips.
few–many, ± nodding, in paniculiform or corymbiform arrays, bracts leafy or much reduced.
tan to stramineous, 2.5–3.5 mm, apical collars 0.1–0.2 mm, shiny;
pappi 9–11 mm.
brownish, 3.4–5 mm, apical collars tan;
pappi 12–15 mm.
perennials, 50–220 cm; woody tap-rooted caudices with numerous coarse, fibrous lateral roots, sometimes forming new rosettes from root sprouts.
= 34.
Cirsium palustre
Cirsium fontinale
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 3 (3 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Cypselae 4.1–5 mm; phyllary spines 1–2 mm | var. fontinale |
1. Cypselae 3.4–4.1 mm; phyllary spines 2–6 mm | → 2 |
2. Longer spines of cauline leaves 10–18 mm; most phyllaries without marginal spines | var. campylon |
2. Longer spines of cauline leaves 4–7 mm; many outer phyllaries with marginal spines | var. obispoense |
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