Cirsium vulgare |
Cirsium rhothophilum |
|
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bull or common or spear thistle, bull thistle, chardon vulgaire ou lancéolé, common thistle, gros chardon, piqueux, spear thistle |
surf thistle |
|
Habit | Biennials, 30–200(–300) cm; taproots. | Biennials or short-lived, usually monocarpic perennials, 10–100 cm; taprooted with simple or branched caudices. |
Stems | 1–many, erect or ascending, branches few–many, ascending, villous with septate trichomes. |
1–several, spreading to erect, bushlike or forming low rounded mounds, gray-tomentose with appressed feltlike trichomes; branches 0–several, inclined to ascending, stiff. |
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 elliptic to ovate, 10–25 cm, strongly undulate, usually broadly pinnatifid, lobes entire or coarsely few-toothed or -lobed, main spines abrupt, 1–4 mm, faces gray-white-tomentose with appressed feltlike, non-septate trichomes; basal present or withered at flowering, winged-petiolate; principal cauline well distributed, winged-petiolate to sessile, gradually reduced, bases clasping with expanded auricles; distal reduced, spines to 8 mm. |
Peduncles | 1–6 cm. |
0–7 cm. |
Involucres | hemispheric to campanulate, 3–4 × 2–4 cm, loosely arachnoid-tomentose. |
hemispheric or campanulate, 3–4 × 4–6 cm, densely arachnoid. |
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 pale yellow, 20–34 mm, tubes 11–15 mm, throats 5–8 mm, lobes 5–8 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, linear, abaxial faces without glutinous ridge; outer and mid bases short- appressed, margins spiny-ciliate, apices long, spreading to erect, spines straight, 2–5 mm; apices of inner flattened or spine-tipped, serrate to scabrid, sometimes pectinately fringed. |
Heads | few–many in corymbiform or paniculiform arrays. |
1–many, erect, terminal on branches in subcapitate to congested, corymbiform arrays, closely subtended by clustered, ± leafy bracts. |
Cypselae | light brown with darker streaks, 3–4.5 mm, apical collar not differentiated; pappi 20–30 mm. |
light–brown to black, 5–7 mm, apical collars whitish, 0.2–0.3 mm; pappi 15–25 mm. |
2n | = 68. |
= 34. |
Cirsium vulgare |
Cirsium rhothophilum |
|
Phenology | Flowering mostly summer (Jun–Sep), year round in areas with mild climates. | Flowering mostly spring–summer (Apr–Aug), occasionally year round. |
Habitat | Invasive weed of disturbed sites, pastures, meadows, forest openings, roadsides | Coastal dunes and bluffs |
Elevation | 0–2200 m (0–7200 ft) | 0–20 m (0–100 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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CA |
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.) |
Of conservation concern. Cirsium rhothophilum is endemic to the dunes of southern San Luis Obispo and northern Santa Barbara counties. It rarely forms hybrids with C. occidentale var. occidentale and C. scariosum var. citrinum. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 19, p. 109. | FNA vol. 19, p. 161. |
Parent taxa | Asteraceae > tribe Cardueae > Cirsium | Asteraceae > tribe Cardueae > Cirsium |
Sibling taxa | ||
Synonyms | Carduus vulgaris, Carduus lanceolatus | Carduus maritima |
Name authority | (Savi) Tenore: Fl. Napol. 5: 209. (1835) | S. F. Blake: J. Wash. Acad. Sci. 21: 336. (1931) |
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