Sonchus arvensis subsp. arvensis
Photo: parent species Sonchus arvensis · (c) Dmitriy Bochkov, some rights reserved (CC BY), uploaded by Dmitriy Bochkov · licence
Family: Asteraceae · Type: Herb · Not Native
Sonchus arvensis subsp. arvensis is a non-native California herb in the Asteraceae family.
Perennial sow thistle is a naturalized plant found in southern San Francisco Bay, southern Sacramento Valley (now eradicated), and southern California coastal areas in disturbed, damp soil environments at elevations below 1,800 meters. Flowering from March to June, this plant produces yellow flowers in stalked clusters with glandular-hairy flower heads. Growing with branching stems that can reach moderate heights, it spreads as an agricultural weed in moist agricultural and disturbed landscapes. Its leaves are deeply lobed and arranged alternately along the stem, typical of the sow thistle genus. As an introduced species, it is considered an invasive plant in agricultural and ruderal habitats.
Identification and appearance
Key characters: 3 sympatric species; key differentiators are perennial habit with rhizomes vs annual growth form of co-occurring species
Habitat and range
Habitat: Uncommon. Weed in damp soil
Elevation: < 1800 m
Outside California: North America, native to Europe
Bloom period
Sonchus arvensis subsp. arvensis blooms Mar-Jun.
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 arvensis subsp. arvensis native to California?
No. Sonchus arvensis subsp. arvensis is not native to California (recorded as not native).
When does Sonchus arvensis subsp. arvensis bloom?
Sonchus arvensis subsp. arvensis blooms Mar-Jun.
What plant family does Sonchus arvensis subsp. arvensis belong to?
Sonchus arvensis subsp. arvensis is in the Asteraceae family, genus Sonchus.
What habitat does Sonchus arvensis subsp. arvensis grow in?
Sonchus arvensis subsp. arvensis grows in Uncommon. Weed in damp soil.
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.