Cirsium vulgare |
Cirsium ochrocentrum |
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bull or common or spear thistle, bull thistle, chardon vulgaire ou lancéolé, common thistle, gros chardon, piqueux, spear thistle |
Beaumont thistle, yellowspine thistle |
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Habit | Biennials, 30–200(–300) cm; taproots. | Perennials, 30–90 cm; crown sprouts or runner roots producing adventitious buds. | ||||
Stems | 1–many, erect or ascending, branches few–many, ascending, villous with septate trichomes. |
1–20+, erect or ascending, densely gray-tomentose with non-septate trichomes; branches 0 or few, usually in distal 1/2, ascending. |
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Leaves | blades oblong-lanceolate to obovate, 15–40 × 6–15 cm, margins plane or revolute, coarsely 1–2-pinnatifid with rigidly divergent lobes, sometimes merely spinose-dentate, lobes triangular to lanceolate, entire to spiny-dentate, main spines 2–10 mm, abaxial faces gray-tomentose, villous with septate trichomes along veins, adaxial green, covered with short appressed bristlelike spines, sometimes tomentose when young; basal present or absent at flowering, petioles winged, bases tapered; principal cauline winged-petiolate, mid and distal becoming sessile, well distributed or not, progressively reduced distally, at least distal decurrent as long spiny wings; distal cauline often more deeply lobed than proximal, main lobes rigidly spiny, margins spinulose, otherwise entire. |
blades oblong to narrowly elliptic, 10–30 × 2–8 cm, strongly undulate, margins coarsely dentate or shallowly to deeply pinnatifid with 8–15 pairs of lobes 0.5–2 cm, often revolute, lobes ± triangular, closely spaced, spreading, spinose-dentate and cleft into 2–5 spine-tipped divisions, main spines 5–20 mm, yellowish, abaxial faces densely white-tomentose, adaxial thinly gray-tomentose; basal usually present at flowering, winged-petiolate; principal cauline sessile, progressively reduced distally, bases ± auriculate to long-decurrent as spiny wings; distal cauline usually much reduced, less lobed. |
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Peduncles | 1–6 cm. |
0–4 cm. |
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Involucres | hemispheric to campanulate, 3–4 × 2–4 cm, loosely arachnoid-tomentose. |
ovoid to hemispheric or broadly campanulate, 2.5–4.5 × 2.5–4.5 cm in first-formed heads, often smaller in later ones, loosely arachnoid on phyllary margins or glabrate. |
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Corollas | purple (rarely white), 25–35 mm, tubes 18–25 mm, throats 5–6 mm, lobes 5–7 mm; style tips 3.5–6 mm. |
white or pale lavender to purple, pink, or red, 25–45 mm, tubes 8–25 mm, throats 6–17 mm, lobes 6–15 mm; style tips 2–8 mm. |
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Phyllaries | in 10–12 series, strongly imbricate, linear-lanceolate (outer) to linear (inner), outer and middle appressed, (bases stramineous), margins entire, abaxial faces without glutinous ridge, apices radiating, greenish, spines 2–5 mm; apices of inner phyllaries flat, serrulate to minutely erose. |
in 5–10 series, imbricate, ovate (outer) to linear-lanceolate (inner), margins entire, abaxial faces with narrow glutinous ridge; outer and middle appressed, spines spreading, 3–12 mm; apices of inner often flexuous, expanded and flat, scabrid-margined, sometimes erose, spineless. |
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Heads | few–many in corymbiform or paniculiform arrays. |
1–few, in leafy, ± corymbiform arrays. |
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Cypselae | light brown with darker streaks, 3–4.5 mm, apical collar not differentiated; pappi 20–30 mm. |
light brown, sometimes with lighter or darker streaks, 6–9 mm, apical collars colored like the body, narrow; pappi (white or tawny), 20–40 mm, usually noticeably shorter than corolla. |
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2n | = 68. |
= 30, 31, 32, 34. |
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Cirsium vulgare |
Cirsium ochrocentrum |
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Phenology | Flowering mostly summer (Jun–Sep), year round in areas with mild climates. | |||||
Habitat | Invasive weed of disturbed sites, pastures, meadows, forest openings, roadsides | |||||
Elevation | 0–2200 m (0–7200 ft) | |||||
Distribution |
AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NF; NS; ON; PE; QC; SK; SPM; Eurasia [Introduced in North America]
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AZ; CA; CO; KS; NE; NM; OK; SD; TX; UT; WY; n Mexico
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Discussion | Native to Eurasia, Cirsium vulgare is the only thistle in North America with bristlelike spines borne on the adaxial leaf faces. These structures are variously described in the literature as trichomes (“spreading hirsute,” “scabrous-hispid,” “coarsely hispid,” “rigid, rather pungent setae,” “prickly-hairy”), prickles, or spines (“setose-spinulose,” “appressed and dense spines”). My examination of cleared leaves of C. vulgare indicated that these structures are not epidermal outgrowths (trichomes or prickles) but emerge from fine veinlets within the tissues of the leaf. As such, they are properly treated as spines. Bull thistle is a noxious weed that has invaded disturbed habitats across the continent. Distasteful to livestock, it can increase in heavily grazed pastures. It occurs in a wide variety of habitats. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Varieties 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 19, p. 109. | FNA vol. 19, p. 123. | ||||
Parent taxa | Asteraceae > tribe Cardueae > Cirsium | Asteraceae > tribe Cardueae > Cirsium | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Carduus vulgaris, Carduus lanceolatus | |||||
Name authority | (Savi) Tenore: Fl. Napol. 5: 209. (1835) | A. Gray: Mem. Amer. Acad. Arts, n. s. 4: 110. (1849) | ||||
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