Clokey or Spring Mountains or white-spine thistle

Cirsium clokeyi S. F. Blake, Proc. Biol. Soc. Wash. 51: 8. 1938

Stems erect or ascending, stout, 40–150 cm. Leaf faces glabrous or nearly so. Heads usually short-pedunculate in erect, racemiform arrays or sometimes long-pedunculate in openly corymbiform arrays. Involucres 3–5 cm, glabrous or thinly arachnoid tomentose, individual phyllaries evident. Phyllaries green or purplish-tinged; outer pectinately spiny ¹/2 their length with many lateral spines; apical spines stout. Corollas purple, 24–33 mm, tubes 3.5–7 mm, throats 11–14 mm, lobes 8–12.5 mm. Pappi 16–18 mm. 2n = 34 (as C. clokeyi).

Flowering summer (Jul–Sep). Gravelly slopes, ravines, montane coniferous forests, subalpine forests, alpine scree; of conservation concern; 2300–3500 m; Nev.

Variety clokeyi is endemic to the Spring Range of Clark County. Its range overlaps that of Cirsium arizonicum var. tenuisectum but no hybrids between the two are known.