Cirsium palustre
Cirsium wrightii
cirse ou chardon des marais, European Marsh thistle, European swamp or marsh thistle, European swamp thistle, marsh thistle
Wright's Marsh thistle, Wright's thistle
single, erect, villous to tomentose with jointed trichomes, distally tomentose with fine, unbranched trichomes;
branches 0–few, ascending, (short).
usually 1, erect, glabrous to ± tomentose;
branches many, usually restricted to distal part of stem, 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 to elliptic, 10–60 × 5–20 cm, unlobed and merely spinulose to irregularly dentate or shallowly to deeply pinnatifid, lobes ± broadly triangular, separated by wide sinuses, obtuse to acute, sometimes coarsely toothed or lobed, main spines slender, 1–3 mm, faces thinly arachnoid, soon glabrescent;
basal often present at flowering, petioles slender, ± winged;
cauline progressively reduced, proximal petiolate, mid and distal sessile, long-decurrent;
distalmost linear to narrowly elliptic, bractlike, spinulose to irregularly dentate or shallowly lobed.
0–1 cm.
slender, 1–15 cm.
ovoid to campanulate, 1–1.5 × 0.8–1.3 cm, thinly cobwebby tomentose with fine unbranched trichomes.
ovoid to hemispheric, 1–2 × 1–2 cm, thinly arachnoid, 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.
white to pink-purple, 19–21 mm, tubes 9–10 mm, throats 4–4.5 mm, lobes 5–7 mm;
style tips 2–3.5 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 8–9 series, strongly imbricate, green, lanceolate (outer) to linear (inner), abaxial faces with prominent glutinous ridge;
outer and middle appressed, bodies entire, apices acute, spines spreading, slender, ca. 1 mm;
apices of inner often flexuous, acuminate, flat, scabrid-ciliolate.
few–many in dense clusters at branch tips.
many, in openly paniculiform arrays, borne singly at tips of peduncles.
tan to stramineous, 2.5–3.5 mm, apical collars 0.1–0.2 mm, shiny;
pappi 9–11 mm.
brown, ca. 4.5 mm, apical collars stramineous, 0.2 mm;
pappi 15–16 mm.
= 34.
Cirsium palustre
Cirsium wrightii
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.
Wright’s thistle occurs from the mountains of south-central New Mexico eastward to the cienegas of the adjacent southwestern Great Plains. Cirsium wrightii is listed by the state of New Mexico as a species of concern. The one known site in Cochise County, Arizona, is apparently historic.
Hybrids are known between Cirsium wrightii and C. vinaceum in the Sacramento Mountains of New Mexico. I have observed hummingbird visits to the heads of both species, though C. wrightii shows none of the apparent adaptations to hummingbirds (P. L. Barlow-Irick 2002) that are seen in such taxa as C. occidentale var. candidissimum, C. andersonii, and C. arizonicum.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
BC
Go Botany
MI Flora
PNW Herbaria
WildflowerSearch
iNaturalist
USDA Plants Database
