Lepidium didymum
Lesser swine cress
Photo by Chez Brungraber
Family: Brassicaceae · Type: Herb · Not Native
Lepidium didymum (Lesser swine cress) is a non-native California herb in the Brassicaceae family, recognized by spectacle-shaped fruits, fetid odor, tubercled valve walls.
Lesser swine cress is a naturalized annual found throughout California in disturbed areas, fields, and pastures at elevations below 1,000 meters. Flowering from March to July, this plant produces small white flowers in delicate clusters with petals less than 0.5 millimeters long. Growing with erect to decumbent stems 10 to 45 centimeters tall that branch extensively near the top, it can form dense clusters from multiple stems emerging at the base. Its leaves are distinctively divided, with basal leaves 1 to 6 centimeters long that are 1 to 2-pinnately dissected and gradually becoming smaller and less complex toward the stem tips. The fruit is a unique spectacle-shaped pod, flattened and about 1.5 millimeters long with thick, strongly veined walls.
Identification and appearance
Key characters: 25 sympatric species; key features are spectacle-shaped fruits, fetid odor, tubercled valve walls
Habitat and range
Habitat: Common. Disturbed areas, fields, pastures
Elevation: < 1000 m
California counties: Alameda, Contra Costa, Humboldt, Los Angeles, Mendocino, Orange, Riverside, San Mateo, Sonoma, San Francisco, Butte, Marin, Monterey, Santa Cruz, San Diego, Ventura, Yolo, San Bernardino, Santa Barbara, Solano, Nevada, Sacramento, San Joaquin, Kern, Santa Clara, El Dorado, Amador, San Luis Obispo, Yuba, Glenn, Merced, Napa
Outside California: North America, native to South America, introduced worldwide
Bloom period
Lepidium didymum blooms Mar-Jul.
How to tell it apart
vs Capsella: Small round-to-oval pods versus distinctive triangular heart-shaped pods.; vs Cotula: Mustard with seed pods and 4 petals versus composite with disk flowers only.; vs Soliva: Mustard with flattened seed pods versus composite with spiny achenes.; vs Thysanocarpus: Fruits stand upright or spread versus hanging downward in Thysanocarpus.; vs Lobularia: Flattened oval pods with 1-2 seeds versus inflated round pods with 2 seeds.
Frequently asked questions
Is Lepidium didymum native to California?
No. Lepidium didymum is not native to California (recorded as not native).
When does Lepidium didymum bloom?
Lepidium didymum blooms Mar-Jul.
Where in California does Lepidium didymum grow?
Lepidium didymum occurs in Alameda, Contra Costa, Humboldt, Los Angeles, Mendocino, Orange, Riverside, San Mateo and other counties, at elevations of < 1000 m.
What plant family does Lepidium didymum belong to?
Lepidium didymum is in the Brassicaceae family, genus Lepidium.
What habitat does Lepidium didymum grow in?
Lepidium didymum grows in Common. Disturbed areas, fields, pastures.
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.