Sonchus tenerrimus
Slender sow thistle
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Family: Asteraceae · Type: Herb · Not Native
Sonchus tenerrimus (Slender sow thistle) is a non-native California herb in the Asteraceae family, recognized by finely divided, lacy leaves and low elevation southern California distribution.
Slender sow thistle is a naturalized annual to perennial herb found in the Central Valley, southern California Coast, Channel Islands, and Peninsular Ranges in disturbed sites at elevations generally below 500 meters. Flowering from March to May, this plant produces pale yellow to white flowers in delicate, stalked heads 10 to 12 millimeters long. Growing with slender, much-branched stems 10 to 80 centimeters tall, it spreads readily in open areas. Its leaves are deeply lobed with linear to triangular segments, often with secondary lobes, and range from basal clasping forms to cauline leaves 3 to 20 centimeters long. The fruit is red-brown, 2.5 to 3.5 millimeters long with roughened ribs and a pappus nearly twice the fruit's length.
Identification and appearance
Key characters: Co-occurs with 4 species; distinguished by finely divided, lacy leaves and low elevation southern California distribution
Habitat and range
Habitat: Uncommon. Disturbed sites
Elevation: generally <= 500 m
Outside California: native to southern Europe
Bloom period
Sonchus tenerrimus blooms Mar-May.
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 tenerrimus native to California?
No. Sonchus tenerrimus is not native to California (recorded as not native).
When does Sonchus tenerrimus bloom?
Sonchus tenerrimus blooms Mar-May.
What plant family does Sonchus tenerrimus belong to?
Sonchus tenerrimus is in the Asteraceae family, genus Sonchus.
What habitat does Sonchus tenerrimus grow in?
Sonchus tenerrimus grows in Uncommon. Disturbed sites.
Related species
Other California species in the same genus, family, or bioregion.
- Sonchus arvensis — Perennial sow thistle
- Sonchus arvensis subsp. arvensis
- Sonchus arvensis subsp. uliginosus
- Sonchus asper subsp. asper — Prickly sow thistle
- Sonchus oleraceus — Common sow thistle
- Sonchus sp. — Sow thistle
- Sphaeromeria cana — Gray chickensage
- Sphaeromeria potentilloides — Fivefinger chickensage
- Sphaeromeria potentilloides var. nitrophila — Alkali tansy-sage
- Sphaeromeria potentilloides var. potentilloides — Cinquefoil tansy
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.