Synonyms: Carduus marianus L., Carduus mariae Crantz, Cirsium maculatum Scop., Cathamus maculatum (Scop.) Lam., Silybum maculatum (Scop.) Moench, Silybum mariae (Crantz) Gray, Mariana lactea Hill
Common names: milk thistle; variegated thistle; blessed milk thistle; Virgin Mary's thistle; Lady's milk; Holy thistle; spotted thistle; cabbage thistle; spotted thistle; St. Mary's thistle; white thistle
Silybum marianum (blessed milk thistle) is a winter annual or biennial with prickly leaves (family Asteraceae). It is widely spread throughout California in overgrazed pastures and along fencelines and other disturbed areas. Blessed milk thistle produces tall, dense stands that outcompete native species.Cal-IPC Rating: Limited
Plant Assessment Form - Information gathered by Cal-IPC on the impacts, rate of spread, and distribution of invasive plants in California. Does not include management information.
Weed RIC Management Notes
- Management Notes - Information on management techniques and effectiveness from the University of California Cooperative Extension’s Weed Research & Information Center.
Cal-IPC Newsletter Articles
- Weed biological control agents approved for California. Pitcairn, Michael J.; Smith, Lincoln; Moran, Patrick. Vol 22, Issue 1
- Taking to the air to locate, prioritize and treat effectively. Burger, Jutta C.. Vol 21, Issue 2
- Wildland Weed News. editor. Vol 17, Issue 2
- More about Italian thistle. Massera, Jack. Vol 09, Issue 2
- Control of exotic plants in an herbaceous understory. Perala, Christine; Hoover, Doris A.; Parra-Szijj, E.A.. Vol 01, Issue 3
Cal-IPC Symposium Presentations
Presentations are linked where available. Where a presentation is not available, find more information by reading the abstract in the Cal-IPC Symposia Archive.
- Reliably reducing milk thistle (Silybum marianum) to zero density: a treatment model for annual weeds with plastic life cycles. Summers, Tony M. (2012)
- Control methods: Biological control. Pitcairn, Michael J.; Woods, Dale M. (1998)
Other Silybum marianum Information
- CalPhotos - Images of plants taken mostly in California.
- Calflora - See the distribution of this species on Calflora's map of California.
- CalWeedMapper - Distribution information with ability to determine regional priorities.
- Jepson Online Interchange for California Flora - Information on taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
- USDA PLANTS Database - Federal database with information on identification and distribution, and links to websites in individual states.
- Bugwood - National database from the Center for Invasive Species and Ecosystem Health at the University of Georgia.