Thlaspi arvense

Fan weed

Family: Brassicaceae · Type: annual · Not Native

Fan weed is a naturalized annual found in California in disturbed areas, fields, thickets, bluffs, floodplains, and woodland at elevations below 2,000 meters. Flowering from March to August, this plant produces small white flowers approximately 3 to 4 millimeters long. Growing with glabrous stems 15 to 55 centimeters tall, it develops a distinctive branching structure. Its basal leaves are oblanceolate to obovate, 1 to 5 centimeters long with wavy or toothed margins, while upper stem leaves are sessile. The fruit is uniquely obovate, 0.7 to 2 centimeters wide with a deeply notched tip and distinctive wing-like margins.

Habitat: Disturbed areas, fields, thickets, bluffs, floodplains, woodland

Bloom period: Mar-Aug

Elevation: < 2000 m

Bioregions: CA

California counties: Inyo, Lassen, Modoc, Siskiyou, Los Angeles, Fresno, Yolo, San Bernardino, Alpine, Nevada, Sierra, Plumas, Marin, Sonoma, Placer, Shasta, San Mateo, Butte, Napa, Humboldt, San Diego, Alameda, Stanislaus, Sacramento, Monterey

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