Cirsium pulcherrimum var. pulcherrimum

Common names: Wyoming thistle
Treatment appears in FNA Volume 19. Treatment on page 126. Mentioned on page 128, 152.

Stems from branched or unbranched rootstocks, 15–60(–90) cm, bases often thickened. Adaxial leaf faces glabrous to thinly gray-tomentose. Heads often 4+, in ± elongate arrays. Cypselae often with stramineous apical collars. 2n = 34.


Phenology: Flowering summer (Jun–Aug).
Habitat: Grasslands, sagebrush scrub, coniferous forest openings, roadsides, often in stony soil
Elevation: 1100–2400 m

Distribution

V19-89-distribution-map.gif

Colo., Idaho, Mont., Nebr., Utah, Wyo.

Discussion

Variety pulcherrimum occurs from eastern Montana and northeastern Utah across Wyoming in the Wyoming Basin, Rocky Mountains, and western Great Plains to northern Colorado and northwestern Nebraska. It is likely that it occurs in southeastern Idaho as well. In the online Atlas of the Vascular Flora of Wyoming, several localities are plotted for var. pulcherrimum in Lincoln County, close to the Idaho state line. R. E. Brooks (1986) included Idaho in the range of C. pulcherrimum; I have not seen documentation for such occurrence. Cirsium pulcherrimum (i.e., var. pulcherrimum) is included in the list of Nebraska Plants of Special Concern.

Variety pulcherrimum is known to hybridize with Cirsium eatonii var. murdockii in Wyoming.

Selected References

None.

Lower Taxa

None.
David J. Keil +
(Rydberg) K. Schumann +
Carduus pulcherrimus +
Wyoming thistle +
Colo. +, Idaho +, Mont. +, Nebr. +, Utah +  and Wyo. +
1100–2400 m +
Grasslands, sagebrush scrub, coniferous forest openings, roadsides, often in stony soil +
Flowering summer (Jun–Aug). +
Just’s Bot. Jahresber. +
Compositae +
Cirsium pulcherrimum var. pulcherrimum +
Cirsium pulcherrimum +
variety +