Cirsium palustre
Cirsium edule
cirse ou chardon des marais, European Marsh thistle, European swamp or marsh thistle, European swamp thistle, marsh thistle
cardon, edible thistle
single, erect, villous to tomentose with jointed trichomes, distally tomentose with fine, unbranched trichomes;
branches 0–few, ascending, (short).
usually 1, erect, simple to openly branched in distal 1/2, ± villous with jointed trichomes, sometimes finely arachnoid, sometimes ± glabrate;
branches 0–many, 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 or oblanceolate, 5–50 × 1–10 cm, plane to moderately undulate, coarsely dentate to deeply pinnatifid, lobes 5–10 well separated, linear, narrowly to broadly triangular, spinulose to spiny-dentate or shallowly lobed, main spines 3–10 mm, abaxial faces thinly to densely villous along major veins with septate trichomes, sometimes thinly arachnoid-tomentose, sometimes glabrescent, adaxial glabrous to sparsely villous or shaggy-tomentose along midveins with septate trichomes;
basal often absent at flowering, spiny winged-petiolate or sessile;
principal cauline well distributed, only gradually reduced, bases auriculate-clasping;
distal moderately to strongly reduced, thin, often spinier than the proximal.
0–1 cm.
0–5(–30) cm.
ovoid to campanulate, 1–1.5 × 0.8–1.3 cm, thinly cobwebby tomentose with fine unbranched trichomes.
narrowly ovoid to hemispheric or campanulate, 1.5–3.5 × 1.5–4 cm (including spines), loosely to densely arachnoid with fine, non-septate trichomes.
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.
purple (pink or white), (15–)18–22(–33) mm, tubes 7–11 mm, throats (4–)5–8.5(–13) mm, lobes linear but not filiform, not knobbed at tips, (2–)4.5–7(–10) mm;
style tips 3–4(–5) mm, conspicuously exserted beyond corolla lobes.
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 4–8 series, subequal, green or often purplish, bodies short, appressed, abaxial faces without glutinous ridge, apices stiffly radiating to ascending, straight or flexuous, narrowly linear, plane to acicular, spines straight, slender, 1–10+ mm;
outermost spiny-fringed or entire, mid entire or minutely serrulate;
apices of inner straight, sometimes expanded and erose, flat.
few–many in dense clusters at branch tips.
1–many, erect, often crowded and ± sessile in tight clusters at stem tips, closely subtended by clusters of leafy bracts or not, collectively forming corymbiform or paniculiform arrays.
tan to stramineous, 2.5–3.5 mm, apical collars 0.1–0.2 mm, shiny;
pappi 9–11 mm.
dark brown, 3.5–6.5 mm, apical collars not differentiated;
pappi 9–19(–25) mm.
= 34.
Cirsium palustre
Cirsium edule
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).
The edible thistle has had a convoluted nomenclatural history. The labels on the type collection (BM) bear the following information: “Circium [sic] * edule” and “R. Mountains & plains of Columbia.” When Nuttall published the name, he listed the range as “The plains of Oregon and the Blue Mountains.” The type specimen closely resembles plants from western Oregon, but plants of Cirsium edule are not known to occur in the Blue Mountains. J. T. Howell (1943) noted that the name C. edule had long been in use for two distinctly different species, one with a long, slender corolla tube, short lobes, and a barely exserted style and the other with a stouter corolla with a shorter tube, longer lobes, and a long-exserted style. He applied the name C. edule to the species with the slender corolla, and took up the name C. macounii for the second species. After examining the type of C. edule, A. Cronquist (1953) pointed out that Howell had erred in applying that name to the short-styled species, and described the latter as C. brevistylum. Cronquist expressed doubt as to the collection locality of the type of C. edule, focusing on the Blue Mountains and not noting the duality of the location data on the specimen and in Nuttall’s publication. It is likely that the plants Nuttall observed in the Blue Mountains were C. brevistylum.
J. T. Howell (1960b) resurrected the name Cirsium hallii to apply to a group of Oregon thistles growing west of the Cascade Range, attributing to it a type locality of Salem, Oregon. Howell (1943) had noted that he had borrowed “the type” of C. hallii from the Gray Herbarium. This species had been described (as Cnicus hallii) by Gray based upon three syntypes (one each cited from California, Utah, and Oregon). The specimen examined by Howell was apparently the Oregon collection by [Elihu] Hall that Gray cited. The Utah and California specimens are different taxa. After examining photographs of the holotype of C. edule and the Oregon specimen of C. hallii, and various specimens collected in the area that Howell described as the range of C. hallii, I have concluded that C. hallii and C. edule are clearly conspecific.
Cirsium edule is a polymorphic species much in need of an in-depth field-based investigation. R. J. Moore and C. Frankton (1962) noted that in the northern part of its range, C. edule occurs mostly at elevations from 300 to over 2100 m. However, along the Oregon coast the species occurs on sea bluffs a few meters above the surf. Populations from montane sites are often rather different in appearance from those of lowland areas, and coastal plants differ from those of nearby more interior areas. Both montane and strictly coastal plants tend to be compact with heads tightly crowded and usually with very densely arachnoid involucres. Plants of non-montane interior sites tend to be taller and more openly branched. Plants of interior sites in southern Washington and Oregon have smaller heads with less densely arachnoid involucres than those farther to the north or along the seashore. The spiny tips of the phyllaries may be ascending or may radiate from the head forming a dense, spiny ball.
Hybridization may have played a role in the diversification of Cirsium edule. Hybrids between C. edule var. macounii and C. brevistylum in southern Canada have been named as C. ×vancouveriense R. J. Moore & C. Frankton. Cirsium edule and C. brevistylum overlap extensively in parts of their ranges and hybrids may occur throughout their area of sympatry. Some of the variation in the southern part of the range of C. edule may be a result of past introgression with various forms of C. remotifolium.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Heads mostly borne singly; peduncles 10–30 cm | var. wenatchense |
1. Heads crowded at stem tips; peduncles usually 0–1 cm | → 2 |
2. Phyllary apices plane to acicular, ascending or ± spreading, spines 1–5 mm | var. edule |
2. Phyllary apices long-acicular, widely spreading, spines 5–15 mm | var. macounii |
BC
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