Alternanthera philoxeroides

Alternanthera philoxeroides_alligatorweed_JM DiTomaso
Photo courtesy Joseph DiTomaso

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) and in Los Angeles County. It invades lakes, streams, canals, ponds and irrigation ditches. It was previously used in the aquarium trade.

Rating: High

Cal-IPC Resources

  • 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.
  • CalWeedMapper - Statewide maps, climate models, and reports.
  • Cal-IPC News - Our quarterly newsletter. Each issue is available as a pdf.
  • Cal-IPC Symposium Proceedings - Presentations and papers from our annual Symposium.
  • Don't Plant a Pest! - Select your region to find non-invasive alternatives to ornamental species. Also see our statewide brochure on trees.

    Other Resources

    Symposium Presentations

    • Chornesky, E. A. and C. M. Palmer (1995). Use of biologically based methods to control pest plants:Issues related to federal research, regulation, and implementation. Proceedings California Exotic Pest Plant Council Symposium '95. Pacific Grove, CA.
    • Leavitt, J. R. and C. Pirosko (2002). A brief overview of the California Dept. of Food and Agriculture's A-rated noxious weed education and eradication program. California Exotic Pest Plant Council Symposium 2002. Sacramento, CA.
    • O'Connell, R. A. (1997). Hydrilla: A case study: The state of California's noxious weed eradication programs. California Exotic Pest Plant Council Symposium '97. Concord, CA.
    • O'Connell, R. A. (1999). The state of California's noxious weed eradication programs. California Exotic Pest Plant Council. Sacramento, CA.

    Cal-IPC News Articles

    • Pitcairn, M. (2000). All weeds that have approved biological control agents, accidental introductions and others. CalEPPC News. 8.