Cirsium palustre |
Cirsium texanum |
|
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cirse ou chardon des marais, European Marsh thistle, European swamp or marsh thistle, European swamp thistle, marsh thistle |
Texas or Texas purple or southern thistle, Texas thistle |
|
Habit | Biennials or monocarpic perennials, 30–200(–300) cm; clusters of fibrous roots. | Annuals or biennials, 20–200 cm; taprooted. |
Stems | single, erect, villous to tomentose with jointed trichomes, distally tomentose with fine, unbranched trichomes; branches 0–few, ascending, (short). |
usually single, erect, tomentose to ± glabrate; branches 0–many, usually restricted to distal part, 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 oblong to elliptic, 7–30 × 2–12 cm, unlobed and merely spinulose to irregularly dentate or shallowly to deeply pinnatifid, lobes ± triangular, separated by narrow to wide sinuses, sometimes coarsely dentate or lobed proximally, obtuse to acute, main spines slender to stout, 1–5 mm, abaxial faces arachnoid tomentose, adaxial glabrous or thinly arachnoid; basal often absent at flowering, petioles slender, ± winged; cauline progressively reduced, proximal petiolate, mid and distal broadly sessile, bases ± auriculate-clasping or decurrent 1–3 cm; distalmost linear to lanceolate, bractlike, irregularly dentate or shallowly lobed. |
Peduncles | 0–1 cm. |
slender, 3–30 cm (not overtopped by crowded distal leaves). |
Involucres | ovoid to campanulate, 1–1.5 × 0.8–1.3 cm, thinly cobwebby tomentose with fine unbranched trichomes. |
ovoid to hemispheric, 1.5–2 × 1.5–2 cm, thinly arachnoid, 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 pink-purple, 20–25 mm, tubes 7–10 mm, throats 6–8 mm (noticeably wider than tubes), lobes 4–7 mm; style tips 3–4 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, lanceolate (outer) to linear (inner), abaxial faces with prominent glutinous ridge; outer and middle appressed, bodies entire, acute, spines spreading, slender, 1–5 mm; apices of inner often flexuous, flat, scabrid-ciliolate, acuminate. |
Heads | few–many in dense clusters at branch tips. |
1–many, in openly paniculiform arrays. |
Cypselae | tan to stramineous, 2.5–3.5 mm, apical collars 0.1–0.2 mm, shiny; pappi 9–11 mm. |
brown, 3–5 mm, apical collars not differentiated; pappi 15–16 mm. |
2n | = 34. |
= 22, 23, 24. |
Cirsium palustre |
Cirsium texanum |
|
Phenology | Flowering summer (Jul–Aug). | Flowering spring–summer (Apr–Jul). |
Habitat | Marshes, wet forests | Roadsides, pastures, fields, shrub-tree savannas |
Elevation | 10–800 m (0–2600 ft) | 0–1000 m (0–3300 ft) |
Distribution |
MA; MI; NH; NY; WI; BC; NF; NS; ON; QC; SPM; Europe [Introduced in North America]
|
AR; LA; MO; NM; OK; TX; Mexico (Coahuila, Durango, Nuevo León, San Luis Potosí, Tamaulipas)
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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 texanum ranges from the Chihuahuan Desert regions of trans-Pecos Texas and adjacent southeastern New Mexico across the plains of Texas and southern Oklahoma to southwestern Arkansas and southwestern Louisiana and south into north-central Mexico. D. S. Correll and M. C. Johnston (1970) suggested hybridization between Cirsium texanum and C. undulatum to explain anomalous specimens in the Edwards Plateau and trans-Pecos regions of western Texas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 19, p. 110. | FNA vol. 19, p. 119. |
Parent taxa | Asteraceae > tribe Cardueae > Cirsium | Asteraceae > tribe Cardueae > Cirsium |
Sibling taxa | ||
Synonyms | Carduus palustris | C. austrinum, C. helleri, C. texanum var. stenolepis |
Name authority | (Linnaeus) Scopoli: Fl. Carniol. ed. 2, 2: 128. (1772) | Buckley: Proc. Acad. Nat. Sci. Philadelphia 13: 460. (1862) |
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