Cirsium fontinale var. fontinale
Fountain thistle, Crystal Springs Fountain Thistle
(c) Madeleine Claire, some rights reserved (CC BY), uploaded by Madeleine Claire · licence
Family: Asteraceae · Type: Herb · Native
Conservation status: CNPS 1B.1 · Endangered
Cirsium fontinale var. fontinale (Fountain thistle) is a native California herb in the Asteraceae family, recognized by NONE sympatric; geographically isolated at Crystal Springs Reservoir.
Fountain thistle is a rare (CNPS 1B.1) California native perennial found in the southwestern San Francisco Bay Area at Crystal Springs Reservoir in San Mateo County, growing in serpentine seeps and streams at elevations of 120 to 150 meters. Flowering from May to August, this plant produces purple-red flowers in nodding heads with spiny, reddish phyllaries up to 20 millimeters long. Growing up to 1.3 meters tall with somewhat reddened stems, it develops an intricate structure with thinly cobwebby leaves covered in velvety hairs. Its leaves are characterized by soft, almost velvet-like surfaces with subtle cobwebby textures that help distinguish this delicate thistle. The fruit is small, measuring 4 to 5 millimeters long, with a distinctive style tip extending 3 to 4 millimeters.
Identification and appearance
Key characters: NONE sympatric; geographically isolated at Crystal Springs Reservoir
Habitat and range
Habitat: Serpentine seeps and streams
Elevation: 120-150 m
Bloom period
Cirsium fontinale var. fontinale blooms May-Aug.
Conservation status
CNPS 1B.1 · Endangered
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 fontinale var. fontinale native to California?
Yes. Cirsium fontinale var. fontinale is native to California (recorded as native).
When does Cirsium fontinale var. fontinale bloom?
Cirsium fontinale var. fontinale blooms May-Aug.
What plant family does Cirsium fontinale var. fontinale belong to?
Cirsium fontinale var. fontinale is in the Asteraceae family, genus Cirsium.
Is Cirsium fontinale var. fontinale rare or endangered?
Cirsium fontinale var. fontinale carries California Rare Plant Rank 1B.1, state rank S1.
What habitat does Cirsium fontinale var. fontinale grow in?
Cirsium fontinale var. fontinale grows in Serpentine seeps and streams.
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 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.