Lactuca virosa
Bitter lettuce
(c) Andreas Rockstein, some rights reserved (CC BY-SA) · licence
Family: Asteraceae · Type: Herb · Not Native
Lactuca virosa (Bitter lettuce) is a non-native California herb in the Asteraceae family, recognized by . Key features: persistent basal rosette, unique wing-margined fruits.
Bitter lettuce is a naturalized biennial found in northern San Francisco Bay and northern South Coast Ranges on disturbed, shrubby, and wooded slopes at elevations below 600 meters. Flowering from June to August, this plant produces pale yellow flowers in clusters with heads 3 to 4 centimeters in diameter. Growing 0.6 to 2 meters tall with an erect stem that is glabrous or bristly near the base, it forms a persistent basal rosette of oblanceolate to obovate leaves. Its leaves range from dentate to shallowly lobed, with lower leaves having winged petioles and upper leaves widely clasping the stem with prickly-bristly midveins. The fruit has 5 to 9 ribs on each face, with a dark body, wing-margined edges, and a white beak approximately equal in length to the body.
Identification and appearance
Key characters: 2 sympatric species. Key features: persistent basal rosette, unique wing-margined fruits
Habitat and range
Habitat: Disturbed, shrubby and wooded slopes
Elevation: < 600 m
Outside California: native to Europe
Bloom period
Lactuca virosa blooms Jun-Aug.
How to tell it apart
vs Sonchus: Look at seeds - Lactuca seeds have a distinct beak/neck, Sonchus bristles attach directly to seed.; vs Taraxacum: Taraxacum has all basal leaves on leafless stalks, Lactuca has leafy branching stems.; vs Helminthotheca: Helminthotheca has spiny-bristly outer phyllaries and yellow-orange flowers, Lactuca has smooth phyllaries.; vs Brassica: Brassica has 4-petaled cruciform flowers and long seed pods, not composite heads with bristly seeds.; vs Stephanomeria: Stephanomeria has only 3-9 flowers per small head, Lactuca has many more flowers per head.
Frequently asked questions
Is Lactuca virosa native to California?
No. Lactuca virosa is not native to California (recorded as not native).
When does Lactuca virosa bloom?
Lactuca virosa blooms Jun-Aug.
What plant family does Lactuca virosa belong to?
Lactuca virosa is in the Asteraceae family, genus Lactuca.
What habitat does Lactuca virosa grow in?
Lactuca virosa grows in Disturbed, shrubby and wooded slopes.
Related species
Other California species in the same genus, family, or bioregion.
- Lactuca biennis — Biennial wild lettuce
- Lactuca canadensis — Canada lettuce
- Lactuca ludoviciana — Biannual lettuce
- Lactuca saligna — Narrow leaved wild lettuce
- Lactuca serriola — Prickly lettuce
- Lactuca sp. — Lettuce
- Laennecia coulteri — Coulter's horseweed
- Laennecia sp.
- Lagophylla diabolensis — Diablo Range hare-leaf
- Lagophylla dichotoma — Forked hareleaf
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.