Xanthium spinosum

Spiny cocklebur, spiny clotbur

Family: Asteraceae · Type: annual · Native

Spiny cocklebur is a naturalized annual found in the California Floristic Province in disturbed, seasonally wet sites including grasslands, marshes, and watercourses at elevations below 1,875 meters. Flowering from July to October, this plant produces small, inconspicuous flowers in heads without an involucre. Growing with minutely strigose stems 10 to 60 centimeters tall, occasionally reaching up to 120 centimeters in height, it spreads across disturbed landscapes with a weedy growth habit. Its leaves are pinnately veined and often pinnately 3-lobed, with blades 4 to 8 centimeters long and 1 to 3 centimeters wide, featuring entire or slightly toothed margins. The plant produces distinctive spiny burs 10 to 12 millimeters long that easily attach to clothing and animal fur.

Habitat: Disturbed, seasonally wet, often alkaline sites, in grassland, marshes, watercourses

Bloom period: Jul-Oct

Elevation: < 1875 m

Bioregions: CA-FP

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