Carduus acanthoides subsp. acanthoides

Plumeless thistle, Plumeless Thistle

Family: Asteraceae · Type: biennial · Not Native

Conservation status: Cal-IPC Yes

Plumeless thistle is a naturalized biennial found in northern California coastal ranges, northern Sierra Nevada, northern central Coast Ranges, and the Modoc Plateau in roadsides, pastures, and disturbed areas at elevations below 1,300 meters. Flowering from July to November, this aggressive plant produces distinctive purple flowers in spheric or hemispheric heads 1 to 2.5 centimeters in diameter. Growing 3 to 5 meters tall with strongly spiny-winged stems that are nearly glabrous to loosely woolly, it forms dense clusters of flowering heads. Its basal leaves are 10 to 30 centimeters long, deeply lobed with spiny teeth and sparse hairs, creating a formidable and prickly appearance. The fruit is golden to brown, with a pappus 11 to 13 millimeters long, allowing efficient wind dispersal across disturbed landscapes.

Habitat: Roadsides, pastures, disturbed areas

Bloom period: Jul-Nov

Elevation: < 1300 m

Bioregions: NCoRI, n SN, n CCo, n SCoRO, MP

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