Cirsium palustre |
Cirsium andrewsii |
|
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cirse ou chardon des marais, European Marsh thistle, European swamp or marsh thistle, European swamp thistle, marsh thistle |
Franciscan thistle |
|
Habit | Biennials or monocarpic perennials, 30–200(–300) cm; clusters of fibrous roots. | Biennials (or short–lived monocarpic perennials), 60–200 cm; taprooted. |
Stems | single, erect, villous to tomentose with jointed trichomes, distally tomentose with fine, unbranched trichomes; branches 0–few, ascending, (short). |
several, erect to spreading, thinly arachnoid, soon glabrous; branches ± fleshy, usually much branched proximally, spreading to 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, 30–75 × 10–20 cm, shallowly to deeply pinnatifid, lobes oblong to ovate, unlobed or with several prominent secondary lobes or large teeth, obtuse to acute, main spines 2–7 mm, abaxial gray arachnoid-tomentose, adaxial faces thinly arachnoid, glabrate; basal often present at flowering, spiny winged-petiolate; principal cauline sessile, bases clasping with broad, spiny-margined auricles, reduced distally, spinier than proximal; distal much reduced, spines 7–20 mm. |
Peduncles | 0–1 cm. |
0–7 cm. |
Involucres | ovoid to campanulate, 1–1.5 × 0.8–1.3 cm, thinly cobwebby tomentose with fine unbranched trichomes. |
ovoid to hemispheric or campanulate, 1.5–3 × 1.5–5 cm, sparsely to densely arachnoid, finely short-ciliate. |
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. |
dark reddish purple, 17–24 mm, tubes 8–11 mm, throats 3.5–6 mm, lobes 5–7 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 ca. 6 series, dark green or brown or with stramineous margins and a darker central zone, imbricate, linear-lanceolate (outer) to linear (inner), abaxial faces without glutinous ridge; outer and mid bodies appressed, spiny-ciliate, apices long-spreading to ascending long-acuminate, spines straight, stout, 5–15 mm; apices of inner straight or twisted, long, entire, flat or spine-tipped. |
Heads | few–many in dense clusters at branch tips. |
several–many, in congested corymbiform arrays. |
Cypselae | tan to stramineous, 2.5–3.5 mm, apical collars 0.1–0.2 mm, shiny; pappi 9–11 mm. |
dark brown, 4–5 mm, apical collars narrow; pappi 15 mm. |
2n | = 34. |
= 32. |
Cirsium palustre |
Cirsium andrewsii |
|
Phenology | Flowering summer (Jul–Aug). | Flowering spring–summer (May–Sep). |
Habitat | Marshes, wet forests | Headlands, ravines, seeps near coast, sometimes on serpentine |
Elevation | 10–800 m (0–2600 ft) | 0–100 m (0–300 ft) |
Distribution |
MA; MI; NH; NY; WI; BC; NF; NS; ON; QC; SPM; Europe [Introduced in North America]
|
CA
|
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.) |
Of conservation concern. Cirsium andrewsii occurs along the coast of north-central California from San Mateo to Marin counties. It reportedly hybridizes with C. quercetorum (F. Petrak 1917; J. T. Howell 1960b). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 19, p. 110. | FNA vol. 19, p. 141. |
Parent taxa | Asteraceae > tribe Cardueae > Cirsium | Asteraceae > tribe Cardueae > Cirsium |
Sibling taxa | ||
Synonyms | Carduus palustris | Cnicus andrewsii |
Name authority | (Linnaeus) Scopoli: Fl. Carniol. ed. 2, 2: 128. (1772) | (A. Gray) Jepson: Fl. W. Calif., 506. (1901) |
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