Centaurea jacea ssp. pratensis
Synonyms: Centaurea debeauxii Gren. & Godr., Centaurea x pratensis; Centaurea jacea L. x Centaurea nigra L.
Common names: meadow knapweed
Centaurea jacea ssp. pratensis (=Centaurea debeauxii or C. jacea x C. nigra or C. x pratensis) (meadow knapweed) is a bushy perennial (family Asteraceae) found in a small number of disturbed areas in Siskiyou, Del Norte, and Humboldt Counties in northwestern California. Meadow knapweed reproduces by seed and via shoots from the parent plant, and is known to resprout from root fragments after cultivation. The seeds can also be spread by irrigation systems and vehicles. Meadow knapweed spreads very rapidly and is listed as a noxious weed in several western states as well as California.Cal-IPC Rating: Moderate — Alert
CDFA Rating: A
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.
Species ID Card
Invasive Species ID Card - To support field identification of early detection species, Cal-IPC has designed a set of Species ID cards that can be downloaded, printed double-sided, and trimmed to size.
Weed Management NotesNo Weed RIC Management Notes are available for this species. Check for information on other species in the genus on the Weed RIC site.
Cal-IPC Newsletter Articles
- Celebrating park stewards. Cal-IPC. Vol 24, Issue 2
- CDFA expands noxious weed list and revises process. Kelch, Dean. Vol 23, Issue 2
- Weed biological control agents approved for California. Pitcairn, Michael J.; Smith, Lincoln; Moran, Patrick. Vol 22, Issue 1
- Jepson Manual 2nd ed. invasive plant name changes. Brusati, Elizabeth. Vol 20, Issue 2
- New weed alerts!. DiTomaso, Joe. Vol 13, Issue 4
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.
- 2005 Cal-IPC weed alerts, new invasions, recent expansions, and a few others to be on the look-out for. DiTomaso, Joseph M. (2005)
- 2003 Cal-IPC red alert! New invasions, recent expansions, and a few others to be on the look-out For…. Tu, Mandy; Randall, John M. (2003)
- 2002 Red alert! New introductions and recent expansions in California. Tu, Mandy; Randall, John M. (2002)
Other Centaurea jacea ssp. pratensis Information
- CalPhotos - Images of plants taken mostly in California.
- Calflora - See the distribution of this species on Calflora's map of California.
- 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.
- EDD MapS - North American distribution based on Early Detection and Distribution Mapping System.