Cirsium vulgare |
Cirsium texanum |
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bull or common or spear thistle, bull thistle, chardon vulgaire ou lancéolé, common thistle, gros chardon, piqueux, spear thistle |
Texas or Texas purple or southern thistle, Texas thistle |
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Habit | Biennials, 30–200(–300) cm; taproots. | Annuals or biennials, 20–200 cm; taprooted. |
Stems | 1–many, erect or ascending, branches few–many, ascending, villous with septate trichomes. |
usually single, erect, tomentose to ± glabrate; branches 0–many, usually restricted to distal part, 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 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 | 1–6 cm. |
slender, 3–30 cm (not overtopped by crowded distal leaves). |
Involucres | hemispheric to campanulate, 3–4 × 2–4 cm, loosely arachnoid-tomentose. |
ovoid to hemispheric, 1.5–2 × 1.5–2 cm, thinly arachnoid, glabrate. |
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 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 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 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 corymbiform or paniculiform arrays. |
1–many, in openly paniculiform arrays. |
Cypselae | light brown with darker streaks, 3–4.5 mm, apical collar not differentiated; pappi 20–30 mm. |
brown, 3–5 mm, apical collars not differentiated; pappi 15–16 mm. |
2n | = 68. |
= 22, 23, 24. |
Cirsium vulgare |
Cirsium texanum |
|
Phenology | Flowering mostly summer (Jun–Sep), year round in areas with mild climates. | Flowering spring–summer (Apr–Jul). |
Habitat | Invasive weed of disturbed sites, pastures, meadows, forest openings, roadsides | Roadsides, pastures, fields, shrub-tree savannas |
Elevation | 0–2200 m (0–7200 ft) | 0–1000 m (0–3300 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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AR; LA; MO; NM; OK; TX; Mexico (Coahuila, Durango, Nuevo León, San Luis Potosí, Tamaulipas)
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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 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. 109. | FNA vol. 19, p. 119. |
Parent taxa | Asteraceae > tribe Cardueae > Cirsium | Asteraceae > tribe Cardueae > Cirsium |
Sibling taxa | ||
Synonyms | Carduus vulgaris, Carduus lanceolatus | C. austrinum, C. helleri, C. texanum var. stenolepis |
Name authority | (Savi) Tenore: Fl. Napol. 5: 209. (1835) | Buckley: Proc. Acad. Nat. Sci. Philadelphia 13: 460. (1862) |
Web links |
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