Cirsium andersonii
Anderson's thistle
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Family: Asteraceae · Type: Herb · Native
Cirsium andersonii (Anderson's thistle) is a native California herb in the Asteraceae family, recognized by large bright rose-purple corollas and distinctive phyllary tips are key.
Anderson's thistle is a California native perennial herb found in the Klamath Ranges, Cascade Range, Sierra Nevada, and North Coast Mountains in open woodland and forest areas at elevations of 1,100 to 3,150 meters. Flowering from July to September, this plant produces bright rose-purple flowers in heads 3 to 5 centimeters wide with distinctive lanceolate phyllaries. Growing with stems 4 to 7 tall with multiple branches that are nearly glabrous or minutely hairy, it develops from runner roots. Its leaves are green on top with a persistently gray-tomentose underside, with lower leaves up to 35 centimeters long featuring coarsely dentate or lobed blades and spiny-winged petioles. The flowers have long, purple-tipped inner phyllaries and a corolla that reaches 30 to 45 millimeters in length.
Identification and appearance
Key characters: 29 sympatric species; large bright rose-purple corollas and distinctive phyllary tips are key
Habitat and range
Habitat: Open places, woodland, forest
Elevation: (250)1100-3150 m
Outside California: to southeastern Idaho, Nevada
Bloom period
Cirsium andersonii blooms Jul-Sep.
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 andersonii native to California?
Yes. Cirsium andersonii is native to California (recorded as native).
When does Cirsium andersonii bloom?
Cirsium andersonii blooms Jul-Sep.
What plant family does Cirsium andersonii belong to?
Cirsium andersonii is in the Asteraceae family, genus Cirsium.
What habitat does Cirsium andersonii grow in?
Cirsium andersonii grows in Open places, woodland, forest.
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.