Cirsium vulgare |
Cirsium nuttallii |
|
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bull or common or spear thistle, bull thistle, chardon vulgaire ou lancéolé, common thistle, gros chardon, piqueux, spear thistle |
Nuttall's thistle |
|
Habit | Biennials, 30–200(–300) cm; taproots. | Biennials, 20–350 cm; taprooted. |
Stems | 1–many, erect or ascending, branches few–many, ascending, villous with septate trichomes. |
usually single, erect, glabrous or villous with septate trichomes; branches few–many, 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 narrowly to broadly elliptic, (10–)15–60 × (2–)5–15 cm, thin, ± flexible, deeply pinnatifid, lobes narrow, spreading, coarsely dentate or lobed, main spines 2–5 mm, abaxial faces thinly tomentose but often wholly glabrate in age, adaxial glabrous or sparsely villous with septate trichomes; basal often absent at flowering, petioles slender, winged, bases tapered; principal cauline becoming sessile and gradually reduced distally, bases spiny-lobed, sometimes decurrent; distal reduced to linear bracts. |
Peduncles | 1–6 cm. |
1–15 cm, essentially naked (not overtopped by crowded distal leaves). |
Involucres | hemispheric to campanulate, 3–4 × 2–4 cm, loosely arachnoid-tomentose. |
hemispheric to campanulate, 1.5–2.5 × 1–2.5 cm, thinly arachnoid or 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, lavender, or purple, 17–25 mm, tubes 5–11 mm, throats 4–7 mm (noticeably wider than tubes), lobes 5–7 mm; style tips 3–4.5 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 6–10 series, strongly imbricate, green or brownish, ovate or elliptic (outer) to linear-lanceolate (inner), abaxial faces with narrow glutinous ridge; outer and middle appressed, bodies entire, spines abruptly spreading, slender, 1–2(–3) mm; apices of inner often flexuous, flat, attenuate. |
Heads | few–many in corymbiform or paniculiform arrays. |
few–many, in open corymbiform or paniculiform arrays. |
Cypselae | light brown with darker streaks, 3–4.5 mm, apical collar not differentiated; pappi 20–30 mm. |
dark brown, 3–4 mm, apical collars stramineous, 0.5 mm; pappi 17–21 mm (longer bristles shorter than corollas). |
2n | = 68. |
= 24, 26, 28. |
Cirsium vulgare |
Cirsium nuttallii |
|
Phenology | Flowering mostly summer (Jun–Sep), year round in areas with mild climates. | Flowering summer (Jun–Aug). |
Habitat | Invasive weed of disturbed sites, pastures, meadows, forest openings, roadsides | Roadsides, ditches, woodlands, usually in damp soil |
Elevation | 0–2200 m (0–7200 ft) | 0–100 m (0–300 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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AL; FL; GA; LA; MS; NC; SC; TX; VA
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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 nuttallii occurs on the southern coastal plain from southeastern Virginia to southern Florida and west to eastern Louisiana. (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 | Carduus glaber, Carduus nuttallii |
Name authority | (Savi) Tenore: Fl. Napol. 5: 209. (1835) | de Candolle: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 6: 651. (1838) |
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