Greene’s thistle

Involucres 1.5–5 cm diam. Corollas white or pale lavender. 2n = 32, 34, 36 (as C. subniveum).

Flowering summer (Jun–Aug). Arid slopes, roadsides, grasslands, sagebrush scrub, pinyon-juniper woodlands, montane coniferous forests; 750–2800 m; Calif., Idaho, Nev., Oreg., Utah, Wash., Wyo.

Variety inamoenum grows from the rainshadow slopes of the Sierra Nevada and Cascades eastward across the northern Basin and Range province to the mountains of southern Idaho, western Wyoming, and northeastern Utah. On the slopes of Steens Mountain in eastern Oregon it forms hybrids with Cirsium eatonii var. peckii. In the Snake Range it apparently hybridizes with C. eatonii var. viperinum.