Cirsium occidentale var. compactum
Compact cobwebby thistle
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Family: Asteraceae · Type: Herb · Native
Conservation status: CNPS 1B.2
Cirsium occidentale var. compactum (Compact cobwebby thistle) is a native California herb in the Asteraceae family, recognized by distinctive low growth form and large heads.
Compact cobwebby thistle is a rare (CNPS 1B.2) California native biennial found in northern San Luis Obispo and Monterey counties on coastal bluffs at elevations below 50 meters. Flowering from February to July, this plant produces dark rose-purple flowers in dense, cobwebby heads up to 8 centimeters wide. Growing as a low, mound-like plant 3 to 30 centimeters tall, it forms compact clusters with closely packed stems. Its leaves are large and closely subtend the flower heads, with the middle phyllary tips spreading and reaching 1 to 2 centimeters long. This distinctive thistle creates dense, low-growing clusters that blend seamlessly into coastal bluff landscapes.
Identification and appearance
Key characters: 11 sympatric species; distinctive low growth form and large heads are diagnostic
Habitat and range
Habitat: Bluffs
Elevation: < 50 m
Bloom period
Cirsium occidentale var. compactum blooms Feb-Jul.
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 occidentale var. compactum native to California?
Yes. Cirsium occidentale var. compactum is native to California (recorded as native).
When does Cirsium occidentale var. compactum bloom?
Cirsium occidentale var. compactum blooms Feb-Jul.
What plant family does Cirsium occidentale var. compactum belong to?
Cirsium occidentale var. compactum is in the Asteraceae family, genus Cirsium.
Is Cirsium occidentale var. compactum rare or endangered?
Cirsium occidentale var. compactum carries California Rare Plant Rank 1B.2, state rank S2.
What habitat does Cirsium occidentale var. compactum grow in?
Cirsium occidentale var. compactum grows in Bluffs.
Related species
Other California species in the same genus, family, or bioregion.
- Cirsium occidentale var. coulteri — Coulter's thistle
- Cirsium occidentale var. lucianum — Cuesta ridge thistle
- Cirsium occidentale var. occidentale — Cobwebby thistle
- Cirsium occidentale var. venustum — Venus thistle
- Cirsium ochrocentrum var. ochrocentrum — Yellowspine thistle
- Cirsium praeteriens — Lost thistle
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.