Cirsium occidentale var. occidentale
Cobwebby thistle, Cobwebby Thistle
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Family: Asteraceae · Type: Herb · Native
Cirsium occidentale var. occidentale (Cobwebby thistle) is a native California herb in the Asteraceae family, recognized by cobwebby phyllaries and coastal habitat.
Cobwebby thistle is a California native biennial found in southern Northern Coast, western Central Western, and western Southwestern California in grasslands, coastal dunes, oak woodlands, and scrublands, typically at elevations below 200 meters. Flowering from March to July, this plant produces lavender to bright purple flowers in large heads approximately 3 to 4 centimeters in diameter. Growing erect with stems 30 to 150 centimeters tall, it develops distinctive cobwebby involucres with needle-like to lanceolate phyllaries that spread outward. Its leaves are arranged to create a striking architectural form, with phyllaries that appear delicately interwoven like spider silk. The flower heads are well-elevated above the plant's lower leaves, creating a dramatic silhouette in its native grassland habitats.
Identification and appearance
Key characters: 32 sympatric species; cobwebby phyllaries and coastal habitat help distinguish
Habitat and range
Habitat: Grassland, coastal dunes, oak woodland, scrubland, often disturbed areas
Elevation: generally < 200 m
Bloom period
Cirsium occidentale var. occidentale blooms Mar-Jul.
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. occidentale native to California?
Yes. Cirsium occidentale var. occidentale is native to California (recorded as native).
When does Cirsium occidentale var. occidentale bloom?
Cirsium occidentale var. occidentale blooms Mar-Jul.
What plant family does Cirsium occidentale var. occidentale belong to?
Cirsium occidentale var. occidentale is in the Asteraceae family, genus Cirsium.
What habitat does Cirsium occidentale var. occidentale grow in?
Cirsium occidentale var. occidentale grows in Grassland, coastal dunes, oak woodland, scrubland, often disturbed areas.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
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.