Cirsium fontinale var. campylon

Mount hamilton thistle, Mount Hamilton Fountain Thistle

Family: Asteraceae · Type: perennial · Native

Conservation status: CNPS 1B.2

Mount hamilton thistle is a rare (CNPS 1B.2) California native perennial found in eastern San Francisco Bay Area bioregion in serpentine seeps and streams at elevations below 750 meters. Flowering from March to October, this plant produces white to purple flowers in distinctive nodding heads with intricate phyllary structures. Growing up to 2 meters tall with green stems, it develops a robust form with densely cobwebby leaves covered in velvety hairs. Its leaves feature longer spines to 18 millimeters, with cauline leaves particularly notable for their complex texture and defensive spiny margins. The plant's uniquely structured flower heads include 65 to 85 phyllaries, with outer phyllaries up to 30 millimeters long and strongly recurved.

Habitat: Serpentine seeps and streams

Bloom period: Mar-Oct

Elevation: < 750 m

Bioregions: e SnFrB.

California counties: Santa Clara, Stanislaus, Alameda

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Jepson eFlora, Cal-IPC, and more.