Synonyms: Bucholzia philoxeroides Mart., Telanthera philoxeroides (Mart.)
Common names: alligatorweed
Alternanthera philoxeroides (alligatorweed) is a noxious herbaceous aquatic perennial (family Amaranthaceae), that forms dense floating mats. This weed grows in the San Joaquin Valley (Tulare and Kings counties), Los Angeles County, and the Sacramento Delta. It invades lakes, streams, canals, ponds and irrigation ditches. It was previously used in the aquarium trade and is currently rapidly expanding in waterways across California.Cal-IPC Rating: High?
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.
Special ReportsYolo County Weed Alert by Brenda Grewell, April 2020
Weed 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
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.
- Continued management and monitoring of alligatorweed (Alternanthera philoxeroides) in the Sacramento-San Joaquin Delta and Suisun Marsh. Kwong, Michael; Earl-Gould, Leslie; Grewell, Brenda; Martinez, Jose (2020)
- The role of public gardens as sentinels of plant invasion. Culley, Theresa; Dreisilker, Kurt; Ryan, Clair; Landel, Hans; Cavallin, Nadia; Arcate Schuler, Jessica; Shultz, Brittany; Gettig, Roger; Havens, Kayri (2020)
- The sky is not the limit – controlling invasive plants with survey and spray drones. Takekawa, John; Edmunds, Tim; Reynolds, Bill; Potter, Chris; Chappell, Steven (2020)
- Weed alerts and other invasive plant highlights for 2020. Burger, Jutta; Price, Robert (2020)
- Alligatorweed in the Delta an early detection rapid response story. O'Brien, Jon (2018)
- New weeds in California: An update. Kelch, Dean (2017)
- Hydrilla: A case study: The state of California’s noxious weed eradication programs. O'Connell, Ross A. (1997)
- Use of biologically based methods to control pest plants:Issues related to federal research, regulation, and implementation. Chornesky, Elizabeth A.; Palmer, Cynthia M. (1995)
Other Alternanthera philoxeroides Information
- Bugwood - National database from the Center for Invasive Species and Ecosystem Health at the University of Georgia.
- CalPhotos - Images of plants taken mostly in California.
- Calflora - Distribution map and records of this species in California.
- CalWeedMapper - Distribution map of this species in California with ability to determine regional priorities.
- EDDMapS - Distribution of this species in North America.
- GBIF - Global distribution information.
- Jepson Interchange - Information on this plant's taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
- USDA PLANTS Database - Information on identification and distribution, with links to websites in individual states.