Cirsium vulgare

Bull thistle

Family: Asteraceae · Type: biennial · Not Native

Conservation status: Cal-IPC Yes

Bull thistle is a naturalized biennial found in California Floristic Province and Great Basin regions in disturbed areas at elevations below 2,350 meters. Flowering from May to October, this aggressive plant produces purple flowers in clustered heads 3 to 4 centimeters wide with distinctive spiny involucres. Growing with tall stems 30 to 200 centimeters high that are loosely tomentose and often glandular-hairy, it spreads widely in open landscapes. Its large leaves are deeply lobed with rigidly spreading spine-margined segments, becoming progressively spinier toward the stem tips with main spines up to 15 millimeters long. The fruit is small, 3 to 4.5 millimeters in length, with a pappus 20 to 30 millimeters long that aids in wind dispersal.

Habitat: Common. Disturbed areas

Bloom period: May-Oct

Elevation: < 2350 m

Bioregions: CA-FP, GB

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