Cirsium vulgare |
Cirsium praeteriens |
|
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bull or common or spear thistle, bull thistle, chardon vulgaire ou lancéolé, common thistle, gros chardon, piqueux, spear thistle |
lost or Palo Alto thistle, lost thistle, Palo Alto thistle |
|
Habit | Biennials, 30–200(–300) cm; taproots. | Biennials or perennials, probably more than 100 cm; rootstock unknown. |
Stems | 1–many, erect or ascending, branches few–many, ascending, villous with septate trichomes. |
stout, erect, loosely arachnoid with fine trichomes and villous with jointed trichomes; branching unknown. |
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 oblanceolate, 15–30+ × 6–8+ cm, divided halfway or more to midveins, lobes linear-lanceolate, rigidly spreading, entire or trifid, acuminate, main spines stout, 5–15 mm, abaxial faces tomentose with fine, non-septate trichomes, villous along major veins with septate trichomes, adaxial glabrescent or sparsely tomentose, villous along veins; basal not observed; cauline well distributed, distally not much reduced, sessile, bases clasping, not decurrent. |
Peduncles | 1–6 cm. |
0–1 cm. |
Involucres | hemispheric to campanulate, 3–4 × 2–4 cm, loosely arachnoid-tomentose. |
hemispheric to broadly campanulate, 3–4 × 4–5+ cm, 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, 30–33 mm, tubes 16 mm, throats 9–12 mm, lobes 5.5–9 mm; style tips 6 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 6–8 series, narrowly lanceolate to linear, outer subequal, rigidly spreading, spines 5–10 mm, inner ± imbricate, bodies appressed, glutinous ridge absent, apices spreading, margins spinulose or scabrid, apices of mid and inner flattened, spineless, scabrid. |
Heads | few–many in corymbiform or paniculiform arrays. |
1–5, terminal and in distal axils in spiciform arrays. |
Cypselae | light brown with darker streaks, 3–4.5 mm, apical collar not differentiated; pappi 20–30 mm. |
light brown, 6 mm, collars also light brown, ca. 0.75 mm; pappi 25–33 mm. |
2n | = 68. |
|
Cirsium vulgare |
Cirsium praeteriens |
|
Phenology | Flowering mostly summer (Jun–Sep), year round in areas with mild climates. | Flowering summer (Jun–Jul). |
Habitat | Invasive weed of disturbed sites, pastures, meadows, forest openings, roadsides | Habitat unknown |
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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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 praeteriens is known only from Santa Clara County, where J. W. Congdon collected it in Palo Alto in 1897 and 1901. It is presumed extinct. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 19, p. 109. | FNA vol. 19, p. 160. |
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) | J. F. Macbride: Contr. Gray Herb. 53: 19. (1918) |
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