Cirsium arizonicum var. tenuisectum
Desert mountain thistle
(c) Jim Morefield, some rights reserved (CC BY) · licence
Family: Asteraceae · Type: Perennial · Native
Conservation status: CNPS 1B.2
Cirsium arizonicum var. tenuisectum (Desert mountain thistle) is a native California perennial in the Asteraceae family, recognized by geographic isolation in desert mountains and deeply divided leaves distinguish it.
Desert mountain thistle is a rare (CNPS 1B.2) California native perennial found in the eastern Desert Mountains, including Clark and New York Mountains, in washes, rocky slopes, scrubland, and woodland at elevations of 1,600 to 2,300 meters. Flowering from July to November, this plant produces pink to red-purple flowers with blossoms 25 to 35 millimeters long, featuring delicate tubular petals. Growing with tall, robust stems reaching up to 1 meter, it develops a distinctive thistle-like structure with sharp spines. Its leaves are deeply divided, covered in cobwebby-like hair on the underside, with main spines measuring 5 to 30 millimeters long. The fruit develops with characteristic thistle-like features, with style tips 1 to 2 millimeters in length.
Identification and appearance
Key characters: 5 sympatric species; geographic isolation in desert mountains and deeply divided leaves distinguish it
Habitat and range
Habitat: Washes, rocky slopes, scrubland, woodland
Elevation: 1600-2300 m
California counties: San Bernardino, Inyo
Outside California: to southern Nevada
Bloom period
Cirsium arizonicum var. tenuisectum blooms Jul-Nov.
Conservation status
CNPS 1B.2
How to tell it apart
vs Carduus: Cirsium has fluffy, feathery seed tufts; Carduus has rough bristles or no pappus and continuous spiny wings down the stem.; vs Silybum: Cirsium leaves are plain green; Silybum has bright white marbling along the leaf veins.; vs Sonchus: Cirsium has thistle-type flowers with spine-tipped bracts; Sonchus has dandelion-like flowers and milky sap.; vs Cynara: Cirsium heads are 1-6 cm across; Cynara heads are massive (4-15 cm, tennis ball sized) with fleshy bases.; vs Centaurea: Cirsium has linear bracts without appendages; Centaurea bracts have fringed or comb-like tips.
Frequently asked questions
Is Cirsium arizonicum var. tenuisectum native to California?
Yes. Cirsium arizonicum var. tenuisectum is native to California (recorded as native).
When does Cirsium arizonicum var. tenuisectum bloom?
Cirsium arizonicum var. tenuisectum blooms Jul-Nov.
Where in California does Cirsium arizonicum var. tenuisectum grow?
Cirsium arizonicum var. tenuisectum occurs in San Bernardino, Inyo, at elevations of 1600-2300 m.
What plant family does Cirsium arizonicum var. tenuisectum belong to?
Cirsium arizonicum var. tenuisectum is in the Asteraceae family, genus Cirsium.
Is Cirsium arizonicum var. tenuisectum rare or endangered?
Cirsium arizonicum var. tenuisectum carries California Rare Plant Rank 1B.2, state rank S2.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
Last updated 2026-09-30
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.