Flora of North America species comparison

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Cirsium eatonii var. viperinum
Photo is of parent taxon

Snake Range thistle
Stems

erect or ascending, 25–40 cm.
Leaf

faces glabrous or nearly so.
Involucres

3–5 cm, thinly arachnoid with non-septate trichomes, individual phyllaries evident.
Corollas

lavender to purple, 29–35 mm, tubes 9–12.5 mm, throats 9–12 mm, lobes 9–11 mm.
Phyllaries

green or purplish-tinged;

outer with numerous lateral spines;

apical spines stout.
Heads

1–5, subsessile or short-pedunculate, in erect, racemiform or corymbiform arrays.
Pappi

20–25 mm.

Cirsium eatonii var. viperinum
Phenology Flowering summer (Jul–Sep).
Habitat Rocky subalpine slopes, open bristlecone pine forests
Elevation 3300–3500 m (10800–11500 ft)
Distribution
from FNA
NV
[BONAP county map]
Discussion

Variety viperinum is apparently endemic to upper elevations of the Snake Range of White Pine County, Nevada. Heads of var. viperinum are similar in size to those of var. clokeyi. These taxa can be distinguished readily by the features in the key. Ranges of the two varieties are separated by about 340 km. Hybridization with Cirsium inamoenum is suspected based upon apparently intermediate specimens.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 19, p. 151.
Parent taxa Asteraceae > tribe Cardueae > Cirsium > Cirsium eatonii
Sibling taxa
C. eatonii var. clokeyi, C. eatonii var. eatonii, C. eatonii var. eriocephalum, C. eatonii var. hesperium, C. eatonii var. murdockii, C. eatonii var. peckii
Name authority D. J. Keil: Sida 21: 212. (2004)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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