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bull thistle, common thistle

Habit Plants biennial, 3–20 dm; taprooted.
Stems

usually single, spreading-villous, sometimes arachnoid.

Leaves

oblong-lanceolate to obovate, 15–40 × 6–15 cm;

margins 1–2-pinnate;

lobes lanceolate to triangular;

spines 2–10(15) mm;

surfaces abaxially tomentose; ± villous, adaxially glabrate to sparsely tomentose, with appressed bristle-like spines;

basal absent or present at flowering, sessile, decurrent, or petiolate.

Involucres

hemispheric to campanulate, 2–4 × 2–4 cm, thinly tomentose.

Florets

corollas 25–35 mm, purple, rarely white;

tubes 18–25 mm;

throats 3–6 mm;

lobes 5–9 mm;

style tips 3.5–6 mm.

Phyllaries

without glutinous ridges;

spines 1–5 mm.

Fruits

3–5 mm, light brown with darker streaks;

pappi 20–30 mm.

Heads

few to many.

Cirsium pulcherrimum

Cirsium vulgare

Distribution
[WildflowerSearch map]
[BONAP county map]
[WildflowerSearch map]
[BONAP county map]
Discussion

Disturbed areas, pastures. Flowering Jun–Sep. 0–2000 m. All ecoregions. CA, ID, NV, WA; throughout North America; worldwide. Exotic.

Cirsium vulgare is our only species with bristle-like spines on the upper leaf surface. This species is considered a noxious weed and is unpalatable to most livestock.

Source Flora of Oregon, volume 2, page 230
Bridget Chipman
Sibling taxa
C. andersonii, C. arvense, C. brevifolium, C. brevistylum, C. ciliolatum, C. cymosum, C. douglasii, C. eatonii, C. edule, C. edule x Cirsium remotifolium, C. inamoenum, C. occidentale, C. ochrocentrum, C. remotifolium, C. scariosum, C. undulatum, C. vulgare
C. andersonii, C. arvense, C. brevifolium, C. brevistylum, C. ciliolatum, C. cymosum, C. douglasii, C. eatonii, C. edule, C. edule x Cirsium remotifolium, C. inamoenum, C. occidentale, C. ochrocentrum, C. remotifolium, C. scariosum, C. undulatum
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