Cirsium scariosum var. congdonii
Rosette thistle, Rosette Thistle
(c) Matt Lavin, some rights reserved (CC BY-SA) · licence
Family: Asteraceae · Type: Perennial · Native
Cirsium scariosum var. congdonii (Rosette thistle) is a native California perennial in the Asteraceae family, recognized by stemless habit with purple flowers diagnostic.
Rosette thistle is a California native perennial found in the Sierra Nevada Mountains, southern Sierra Nevada, and northeastern Sierra Nevada in meadows, springs, and streambanks at elevations of 1,900 to 3,100 meters. Flowering from June to August, this plant produces lavender to purple flowers in heads 2 to 3 centimeters wide, closely surrounded by a basal rosette. Growing with minimal stem development, it forms dense ground-hugging rosettes with leaves that vary from glabrous to cobwebby-hairy on the upper surface. Its leaves are distinctive, ranging from smooth to white-woolly on the undersides, with leaf surfaces showing intricate textural variations. The thistle's flower heads feature involucre phyllaries with spine tips measuring 1 to 4 millimeters long, creating a delicate architectural structure.
Identification and appearance
Key characters: 16 sympatric species; stemless habit with purple flowers diagnostic
Habitat and range
Habitat: Meadows, springs, streambanks
Elevation: 1900-3100 m
California counties: San Bernardino, Mono, Inyo, Tulare, San Diego, Riverside
Outside California: Nevada
Bloom period
Cirsium scariosum var. congdonii blooms Jun-Aug.
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 scariosum var. congdonii native to California?
Yes. Cirsium scariosum var. congdonii is native to California (recorded as native).
When does Cirsium scariosum var. congdonii bloom?
Cirsium scariosum var. congdonii blooms Jun-Aug.
Where in California does Cirsium scariosum var. congdonii grow?
Cirsium scariosum var. congdonii occurs in San Bernardino, Mono, Inyo, Tulare, San Diego, Riverside, at elevations of 1900-3100 m.
What plant family does Cirsium scariosum var. congdonii belong to?
Cirsium scariosum var. congdonii is in the Asteraceae family, genus Cirsium.
What habitat does Cirsium scariosum var. congdonii grow in?
Cirsium scariosum var. congdonii grows in Meadows, springs, streambanks.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-06
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.