Sisymbrium irio
London rocket
Photo by Chez Brungraber
Family: Brassicaceae · Type: Herb · Not Native
Conservation status: Cal-IPC Yes
Sisymbrium irio (London rocket) is a non-native California herb in the Brassicaceae family, recognized by fruits overtopping flowers and thin pedicels.
London rocket is a naturalized annual found in the Great Valley, central Coast, southern Coast Ranges, southwestern California, White and Inyo Mountains, and desert regions in disturbed areas, fields, and pastures at elevations below 1,700 meters. Flowering from January to April, this plant produces yellow flowers 2.5 to 3.5 millimeters long with delicate petals. Growing with erect stems 20 to 60 centimeters tall, it has a smooth or slightly hairy base. Its basal leaves are pinnately lobed with 2 to 6 lateral lobe pairs, ranging from 3 to 12 centimeters long and varying from entire to slightly dentate. The fruit is a long, slender linear pod 3 to 4 centimeters in length that overtops the flowers.
Identification and appearance
Key characters: 4 sympatric species; distinguished by fruits overtopping flowers and thin pedicels
Habitat and range
Habitat: Disturbed areas, fields, pastures
Elevation: < 1700 m
California counties: Los Angeles, Kern, Riverside, San Bernardino, Inyo, Ventura, Alameda, Imperial, Orange, San Diego, San Francisco, San Luis Obispo, Tulare, Fresno, Mono, Santa Barbara, Kings, Glenn, Santa Clara, San Joaquin, Monterey, Santa Cruz, Yolo, Merced, Sacramento, Stanislaus, Butte, San Benito, Colusa, Sutter, Mariposa
Outside California: to Utah, Texas, Baja California, also eastern United States, native to Europe
Bloom period
Sisymbrium irio blooms Jan-Apr.
Conservation status
Cal-IPC Yes
How to tell it apart
vs Hirschfeldia: Sisymbrium pods are unsegmented; shortpod has segmented pods with beaded appearance.; vs Brassica: Sisymbrium pod valves have 3 veins; mustard pod valves have 1 vein.; vs Descurainia: Sisymbrium has undivided leaves on stem; tansy mustard has finely dissected feathery leaves.; vs Caulanthus: Sisymbrium petals are flat; jewelflower petals are crinkled or wavy.; vs Mutarda: Sisymbrium has 3-veined pod valves; check pod surface for vein count.
Frequently asked questions
Is Sisymbrium irio native to California?
No. Sisymbrium irio is not native to California (recorded as not native).
When does Sisymbrium irio bloom?
Sisymbrium irio blooms Jan-Apr.
Where in California does Sisymbrium irio grow?
Sisymbrium irio occurs in Los Angeles, Kern, Riverside, San Bernardino, Inyo, Ventura, Alameda, Imperial and other counties, at elevations of < 1700 m.
What plant family does Sisymbrium irio belong to?
Sisymbrium irio is in the Brassicaceae family, genus Sisymbrium.
Is Sisymbrium irio invasive in California?
Sisymbrium irio is listed by Cal-IPC with an invasiveness rating of Yes.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.