Cirsium eatonii var. hesperium

(Eastwood) D. J. Keil

Sida 21: 212. 2004.

Common names: Tall mountain thistle
Endemic
Basionym: Cnicus hesperius Eastwood Bull. Calif. Acad. Sci., ser. 3, 1: 122. 1898
Synonyms: Cirsium hesperium (Eastwood) Petrak
Treatment appears in FNA Volume 19. Treatment on page 152. Mentioned on page 151.

Stems strictly erect, 50–150 cm. Leaf faces glabrous or nearly so or abaxially finely arachnoid-tomentose and/or villous to tomentose with septate trichomes on one or both faces. Heads usually sessile in stiffly erect, tight spiciform arrays, sometimes also sessile in distal leaf axils. Involucres 2–2.5 cm, tomentose with septate trichomes; outer phyllaries with a few stiff lateral spines; spines of phyllaries slender. Corollas pink or pale to deep purple, 14–21 mm, tubes 4.5–10 mm, throats 3.5–5 mm, lobes 3.5–7 mm. Pappi 8–17 mm.


Phenology: Flowering summer (Jul–Sep).
Habitat: Rocky slopes, subalpine meadows, forest openings
Elevation: 2700–3400 m

Discussion

Variety hesperium is distributed in the San Juan Mountains and Spanish Peaks area of southern Colorado. It differs from var. eriocephalum in its stiffly erect arrays. Plants from the Spanish Peaks area approach var. eriocephalum.

Selected References

None.

Lower Taxa

None.