Sonchus oleraceus
Common sow thistle
Photo by Chez Brungraber
Family: Asteraceae · Type: Herb · Not Native
Sonchus oleraceus (Common sow thistle) is a non-native California herb in the Asteraceae family, recognized by acute clasping lobes, deeply lobed leaves, and cross-wrinkled dark brown fruits.
Common sow thistle is a naturalized annual found throughout California in disturbed places at elevations below 2,500 meters. Flowering all year, this plant produces yellow flowers in heads 10 to 13 millimeters long with ligules approximately equal to the flower tube. Growing with branched stems 10 to 140 centimeters tall, it has a spreading habit that allows it to quickly colonize open areas. Its leaves are primarily lobed, with terminal leaflets often widely arrowhead-shaped, and lower leaves typically tapering or wing-petioled. The fruit is dark brown, 2.5 to 3.8 millimeters long, with cross-wrinkled surfaces and prominent ribs.
Identification and appearance
Key characters: Co-occurs with 5 species; distinguished by acute clasping lobes, deeply lobed leaves, and cross-wrinkled dark brown fruits
Habitat and range
Habitat: Abundant. Disturbed places
Elevation: < 2500 m
Outside California: North America, native to Europe
Bloom period
Sonchus oleraceus blooms All year.
How to tell it apart
vs Taraxacum: Taraxacum has all basal leaves on leafless stalks, Sonchus has tall leafy branching stems.; vs Lactuca: Check seeds - Sonchus has no beak, Lactuca seeds have distinct neck before bristles.; vs Helminthotheca: Helminthotheca has spiny-bristly outer phyllaries creating a prickly appearance, Sonchus phyllaries are smooth.; vs Cirsium: Cirsium has spiny flower heads and disk flowers only, Sonchus has smooth heads with ray flowers.; vs Senecio: Senecio has yellow disk and ray flowers, Sonchus has only yellow ray flowers.
Frequently asked questions
Is Sonchus oleraceus native to California?
No. Sonchus oleraceus is not native to California (recorded as not native).
When does Sonchus oleraceus bloom?
Sonchus oleraceus blooms All year.
What plant family does Sonchus oleraceus belong to?
Sonchus oleraceus is in the Asteraceae family, genus Sonchus.
What habitat does Sonchus oleraceus grow in?
Sonchus oleraceus grows in Abundant. Disturbed places.
Related species
Other California species in the same genus, family, or bioregion.
- Sonchus sp. — Sow thistle
- Sonchus tenerrimus — Slender sow thistle
- Sonchus arvensis — Perennial sow thistle
- Sonchus arvensis subsp. arvensis
- Sonchus arvensis subsp. uliginosus
- Sonchus asper subsp. asper — Prickly sow thistle
- Sphaeromeria cana — Gray chickensage
- Sphaeromeria potentilloides — Fivefinger chickensage
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.