Sinapis alba
White mustard
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Family: Brassicaceae · Type: Herb · Not Native
Sinapis alba (White mustard) is a non-native California herb in the Brassicaceae family, recognized by key differences in petal color intensity and fruit width.
White mustard is a naturalized plant found in the central coastal, southern coastal, and northern coastal interior coast ranges in fields and disturbed areas at elevations below 1,500 meters. Flowering from March to September, this plant produces pale yellow flowers 8 to 12 millimeters wide with delicate petals. Growing 2.5 to 10 meters tall with hairy stems, it develops robust and spreading vegetation. Its leaves are pinnately lobed with 1 to 3 pairs of lateral lobes, ranging 5 to 14 centimeters long and varying from oblong to ovate in shape. The fruit develops in elongated pods 2 to 4.2 centimeters long with spreading pedicels.
Identification and appearance
Key characters: 1 sympatric species; key differences in petal color intensity and fruit width
Habitat and range
Habitat: Fields, disturbed areas
Elevation: < 1500 m
Outside California: North America, native to Eurasia
Bloom period
Sinapis alba blooms Mar-Sep.
How to tell it apart
vs Hirschfeldia: Sinapis pods angle outward from stem; Hirschfeldia pods press flat against stem like they're glued.; vs Raphanus: Sinapis pods clearly two-segmented with multiple veins; Raphanus pods fat and sausage-like without segmentation.; vs Rorippa: Sinapis has large yellow flowers with reflexed sepals; Rorippa has tiny flowers and slim cylindrical pods.
Frequently asked questions
Is Sinapis alba native to California?
No. Sinapis alba is not native to California (recorded as not native).
When does Sinapis alba bloom?
Sinapis alba blooms Mar-Sep.
What plant family does Sinapis alba belong to?
Sinapis alba is in the Brassicaceae family, genus Sinapis.
What habitat does Sinapis alba grow in?
Sinapis alba grows in Fields, disturbed areas.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · 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.