Cirsium eatonii var. murdockii

S. L. Welsh

Great Basin Naturalist 42: 200. 1982.

Common names: Northern mountain thistle
IllustratedEndemicConservation concern
Synonyms: Cirsium murdockii (S. L. Welsh) Cronquist Cirsium polyphyllum (Rydberg) Petrak Cirsium tweedyi (Rydberg) Petrak
Treatment appears in FNA Volume 19. Treatment on page 152. Mentioned on page 126, 151, 156.

Stems erect or ascending, stout, 10–75 cm. Leaf faces glabrous or nearly so or abaxial ± villous and/or tomentose with septate or non-septate trichomes. Heads sessile or short-pedunculate in erect, few-headed, subcapitate or spiciform arrays. Involucres 2–3 cm, thinly to densely tomentose with septate or non-septate trichomes (phyllaries sometimes obscured by tomentum). Phyllaries green or purplish-tinged; outer with few lateral spines; apical spines slender. Corollas white to pink or lavender, 17–23 mm, tubes 6–10 mm, throats 5–8 mm, lobes 3–6 mm. Pappi 11–18 mm. 2n = 34 (as C. tweedyi).

Phenology: Flowering summer (Jul–Sep).
Habitat: Talus slopes, rocky subalpine and alpine ridges, openings in subalpine forests, subalpine meadows
Elevation: 2300–3900 m



Colo., Idaho, Mont., Nev., Utah, Wyo.


Of conservation concern.

Variety murdockii grows in the central Rocky Mountains from central Idaho and southern Montana to western Wyoming and northern Colorado. It also grows in the Ruby Mountains of northern Nevada and the Uintah Mountains of northeastern Utah. Considerable variation occurs in quantity and quality of pubescence of the involucres of var. murdockii. In some individuals the pubescence is so dense that it obscures the phyllary bodies whereas in others the individual phyllaries are clearly visible. Most commonly the pubescence consists primarily of septate trichomes, but sometimes finer non-septate trichomes predominate. Both types of trichomes may be present.

Variety murdockii is known to hybridize with Cirsium pulcherrimum var. pulcherrimum and C. scariosum var. scariosum in Wyoming.

Selected References


Lower Taxa

David J. Keil +
S. L. Welsh +
Cnicus eatonii +
Northern mountain thistle +
Colo. +, Idaho +, Mont. +, Nev. +, Utah +  and Wyo. +
2300–3900 m +
Talus slopes, rocky subalpine and alpine ridges, openings in subalpine forests, subalpine meadows +
Flowering summer (Jul–Sep). +
Great Basin Naturalist +
Illustrated +, Endemic +  and Conservation concern +
Cirsium murdockii +, Cirsium polyphyllum +  and Cirsium tweedyi +
Cirsium eatonii var. murdockii +
Cirsium eatonii +
variety +