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Anderson's thistle

Palouse thistle

Habit Plants perennial, (1.5)4–7(10) dm; taprooted, sometimes with creeping roots. Plants perennial, 2.5–12 dm; taprooted with lateral roots.
Stems

usually 1, sparsely arachnoid-tomentose to glabrate.

1–several, gray-tomentose.

Leaves

elliptic to linear-oblong, 8–20(35) × 2–8 cm, gradually reduced above;

margins coarsely dentate or 1–2-pinnate;

spines 1–5 mm;

surfaces abaxially ± thinly gray-tomentose, adaxially glabrous to sparsely pilose;

basal usually present at flowering, clasping to petiolate.

elliptic to oblanceolate, 12–45 × 2–10 cm;

margins entire to deeply dentate or pinnately lobed;

spines 2–6 mm;

surfaces abaxially densely white-tomentose, adaxially thinly tomentose to glabrate;

basal usually present at flowering, sessile, clasping, or petiolate.

Involucres

broadly cylindric to narrowly campanulate, 3–5 × 2–4 cm, glabrous to thinly tomentose.

hemispheric to campanulate; (1.5)2–3.5 × 2–4 cm.

Florets

corollas 30–45 mm, red, occasionally red-purple;

tubes 10–20 mm;

throats abruptly narrowed to tubes, 10–16 mm;

lobes 9–11 mm;

styles conspicuously exserted;

tips 3.5–5 mm, sometimes geniculate.

corollas 20–28 mm, white to cream-colored, occasionally lavender-tinged;

tubes 8–13 mm;

throats 7–11 mm;

lobes 4–6 mm;

style tips 5–6 mm.

Phyllaries

without glutinous ridges;

spines weak, 1–3 mm; outer short, linear-lanceolate, appressed;

margins entire or spiny-ciliate;

tips long-acuminate; inner linear; long; entire;

tips red to purple; flat.

strongly imbricate, with prominent glutinous ridges;

tips reflexed;

spines fine, 2–5 mm.

Fruits

6–7 mm, brown;

pappi 25–40 mm.

5–6 mm; straw-colored to light brown;

pappi 28–34 mm.

Heads

1–6 per branch;

lateral heads widely spaced along distal portions of branches.

1–few.

Cirsium andersonii

Cirsium brevifolium

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

Open grasslands, montane woodlands. Flowering Jul–Sep. 1500–2500 m. ECas. CA, NV. Native.

Cirsium andersonii, while currently rare in Oregon, is well documented in northern California and Nevada.

Meadows, forest edges, sagebrush areas, roadsides. Flowering Jun–Aug. 200–1500 m. BW, Lava, Owy. ID, WA. Native.

Source Flora of Oregon, volume 2, page 225
Bridget Chipman
Flora of Oregon, volume 2, page 225
Bridget Chipman
Sibling taxa
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. 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
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