Cirsium vulgare |
Cirsium grahamii |
|
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bull or common or spear thistle, bull thistle, chardon vulgaire ou lancéolé, common thistle, gros chardon, piqueux, spear thistle |
Graham's thistle |
|
Habit | Biennials, 30–200(–300) cm; taproots. | Biennials, 50–100 cm; taproots slender and fascicles of thick fibrous roots. |
Stems | 1–many, erect or ascending, branches few–many, ascending, villous with septate trichomes. |
1, erect, thinly arachnoid and/or puberulent to short-pilose, sometimes ± glabrate; branches 0–4, ascending. |
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 oblanceolate to oblong-elliptic, 20–30 × 3–8 cm, spinulose and otherwise entire or coarsely dentate to deeply pinnatifid, lobes entire or coarsely few toothed or lobed, main spines slender, 3–6 mm, abaxial ± persistently gray-tomentose, sometimes pilose along veins, adaxial faces thinly arachnoid and ± glabrate; basal often present at flowering, sessile or narrowly winged-petiolate; principal cauline gradually winged-petiolate or sessile, reduced distally, bases sometimes clasping or short-decurrent; distal cauline ascending, becoming bractlike, narrow, lobed or not. |
Peduncles | 1–6 cm. |
10–30 cm. |
Involucres | hemispheric to campanulate, 3–4 × 2–4 cm, loosely arachnoid-tomentose. |
hemispheric, 2–3 × 2–4 cm, thinly arachnoid or glabrous. |
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. |
deep purple, 22–30 mm, tubes 13–18 mm, throats 4–5 mm, lobes 5–8 mm; style tips 4–4.5 mm. |
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 ca. 8 series, imbricate, proximally brownish, distally dark purplish, lanceolate to linear, margins of outer hispidulous-ciliolate, spiny fringed, pinnately spiny or with scarious appendages, abaxial faces with prominent, glutinous ridge; outer and middle appressed or only apices spreading, bodies minutely spinulose-denticulate, spines erect to ascending, 1.5–2.5 mm; apices of inner phyllaries often flexuous, flat, scabridulous. |
Heads | few–many in corymbiform or paniculiform arrays. |
1–5. |
Cypselae | light brown with darker streaks, 3–4.5 mm, apical collar not differentiated; pappi 20–30 mm. |
tan with dark speckles to dark purplish brown, 4–5.5 mm, apical collars not differently colored; pappi 13–18 mm. |
2n | = 68. |
= 32 (Mexico). |
Cirsium vulgare |
Cirsium grahamii |
|
Phenology | Flowering mostly summer (Jun–Sep), year round in areas with mild climates. | Flowering Jul–Sep. |
Habitat | Invasive weed of disturbed sites, pastures, meadows, forest openings, roadsides | Oak woodlands, coniferous forests, meadows, often in damp soil |
Elevation | 0–2200 m (0–7200 ft) | 1400–2600 m (4600–8500 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; NM; Mexico (Chihuahua, Durango, Sonora)
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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.) |
Cirsium grahamii occurs in the mountains of southeastern Arizona and southwestern New Mexico. It forms hybrid swarms with C. parryi and C. scariosum var. coloradense in the White Mountains of Arizona. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 19, p. 109. | FNA vol. 19, p. 124. |
Parent taxa | Asteraceae > tribe Cardueae > Cirsium | Asteraceae > tribe Cardueae > Cirsium |
Sibling taxa | ||
Synonyms | Carduus vulgaris, Carduus lanceolatus | |
Name authority | (Savi) Tenore: Fl. Napol. 5: 209. (1835) | A. Gray: Smithsonian Contr. Knowl. 5(6): 102. (1853) |
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