The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

bull or common or spear thistle, bull thistle, chardon vulgaire ou lancéolé, common thistle, gros chardon, piqueux, spear thistle

blackland thistle, Engelmann's thistle

Habit Biennials, 30–200(–300) cm; taproots. Biennials or monocarpic perennials, 40–200 cm; taproots and clusters of coarse fibrous roots that often have tuberlike thickenings.
Stems

1–many, erect or ascending, branches few–many, ascending, villous with septate trichomes.

single, erect, often branched above middle, thinly arachnoid-tomentose, ± glabrate;

branches few, 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 elliptic or ovate, 5–20 × 1–10 cm, usually deeply pinnatifid, lobes narrowly to broadly triangular, sinuses broad, rounded (basal and distal cauline sometimes less divided, lobes linear-lanceolate), margins revolute, spreading, entire or spinulose to remotely few-toothed or sharply lobed, main spines slender, 1–5 mm, abaxial faces white-tomentose, adaxial green, villous with septate trichomes or glabrate;

basal usually absent at flowering, winged-petiolate, bases tapered;

principal cauline well distributed, gradually reduced, bases narrowed, sometimes weakly clasping;

distal reduced, widely separated, distalmost bractlike.

Peduncles

1–6 cm.

2–20+ cm, essentially naked with much reduced bracts.

Involucres

hemispheric to campanulate, 3–4 × 2–4 cm, loosely arachnoid-tomentose.

ovoid to broadly cylindric or campanulate, 2.5–3.5 × 2–3 cm, thinly 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.

pink to purple (white), 32–38 mm, tubes 15–20 mm, throats 6–9 mm, lobes 8–11 mm;

style tips 5–6 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 10–12 series, strongly imbricate, greenish with subapical darker central zone, ovate (outer) to lanceolate (inner), abaxial faces with narrow glutinous ridge;

outer and middle entire, bodies appressed, spines abruptly spreading to deflexed, slender, 2–4 mm;

apices of inner phyllaries narrow, flexuous, flattened, entire or finely erose.

Heads

few–many in corymbiform or paniculiform arrays.

1–10+, borne at tips of main stem and branches.

Cypselae

light brown with darker streaks, 3–4.5 mm, apical collar not differentiated;

pappi 20–30 mm.

brown, 5–6 mm, apical collars yellow, ca. 1 mm;

pappi 25–30 mm.

2n

= 68.

= 18 (as C. terrae-nigrae), 20 + 1B.

Cirsium vulgare

Cirsium engelmannii

Phenology Flowering mostly summer (Jun–Sep), year round in areas with mild climates. Flowering spring–summer (May–Jul).
Habitat Invasive weed of disturbed sites, pastures, meadows, forest openings, roadsides Tallgrass prairies, old fields, roadsides, oak savannas, forest edges, in calcareous clay or rarely sandy soils
Elevation 0–2200 m (0–7200 ft) 50–200 m (200–700 ft)
Distribution
from FNA
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]
[WildflowerSearch map]
[BONAP county map]
from FNA
LA; OK; TX
[BONAP county map]
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 engelmannii occurs mostly in the blackland prairies of eastern Texas. It ranges northward into southeastern Oklahoma and eastward to northwestern Arkansas.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 19, p. 109. FNA vol. 19, p. 117.
Parent taxa Asteraceae > tribe Cardueae > Cirsium Asteraceae > tribe Cardueae > Cirsium
Sibling taxa
C. altissimum, C. andersonii, C. andrewsii, C. arizonicum, C. arvense, C. barnebyi, C. brevifolium, C. brevistylum, C. canescens, C. carolinianum, C. ciliolatum, C. clavatum, C. crassicaule, C. cymosum, C. discolor, C. douglasii, C. drummondii, C. eatonii, C. edule, C. engelmannii, C. flodmanii, C. foliosum, C. fontinale, C. grahamii, C. helenioides, C. hookerianum, C. horridulum, C. hydrophilum, C. inamoenum, C. joannae, C. kamtschaticum, C. lecontei, C. longistylum, C. mohavense, C. muticum, C. neomexicanum, C. nuttallii, C. occidentale, C. ochrocentrum, C. ownbeyi, C. palustre, C. parryi, C. perplexans, C. pitcheri, C. praeteriens, C. pulcherrimum, C. pumilum, C. quercetorum, C. remotifolium, C. repandum, C. rhothophilum, C. rydbergii, C. scariosum, C. texanum, C. tracyi, C. turneri, C. undulatum, C. vinaceum, C. virginianum, C. wheeleri, C. wrightii
C. altissimum, C. andersonii, C. andrewsii, C. arizonicum, C. arvense, C. barnebyi, C. brevifolium, C. brevistylum, C. canescens, C. carolinianum, C. ciliolatum, C. clavatum, C. crassicaule, C. cymosum, C. discolor, C. douglasii, C. drummondii, C. eatonii, C. edule, C. flodmanii, C. foliosum, C. fontinale, C. grahamii, C. helenioides, C. hookerianum, C. horridulum, C. hydrophilum, C. inamoenum, C. joannae, C. kamtschaticum, C. lecontei, C. longistylum, C. mohavense, C. muticum, C. neomexicanum, C. nuttallii, C. occidentale, C. ochrocentrum, C. ownbeyi, C. palustre, C. parryi, C. perplexans, C. pitcheri, C. praeteriens, C. pulcherrimum, C. pumilum, C. quercetorum, C. remotifolium, C. repandum, C. rhothophilum, C. rydbergii, C. scariosum, C. texanum, C. tracyi, C. turneri, C. undulatum, C. vinaceum, C. virginianum, C. vulgare, C. wheeleri, C. wrightii
Synonyms Carduus vulgaris, Carduus lanceolatus C. virginianum var. filipendulum, C. terrae-nigrae
Name authority (Savi) Tenore: Fl. Napol. 5: 209. (1835) Rydberg: Fl. Rocky Mts., 1069. (1917)
Web links