Myriophyllum spicatum

Photo courtesy Joseph DiTomaso

Common names: spike watermilfoil

Myriophyllum spicatum (Eurasian watermilfoil) is a common submersed aquatic perennial (family Haloragaceae). Eurasian watermilfoil can be found in freshwater lakes, ponds, and canals with slow-moving waters in northern and central California, particularly in the San Francisco Bay and San Joaquin Valley regions and Lake Tahoe. This plant grows and spreads rapidly, creating dense mats on the water surface. These monotypic mats out-compete native aquatic plants, reducing species diversity.

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

  • Shaw, D., Z. Hymanson, et al. (2011). Effectiveness of aquatic invasive plant control in Emerald Bay, Lake Tahoe. Cal-IPC 2011 Symposium. Tahoe City, CA, California Invasive Plant Council.
  • Caterino, P., D. Freeland, et al. (2008). Lake Tahoe Aquatic Invasive Species Pilot Project - Measuring and adapting standard methods of control for use in an alpine environment. California Invasive Plant Council Symposium 2008. Chico, CA, California Invasive Plant Council.
  • Hunt, T., J. M. DiTomaso, et al. (2007). Applied ecology of Eurasian watermilfoil (Myriophyllum spicatum L.) in Fall River. California Invasive Plant Council Symposium 2007. San Diego, CA, California Invasive Plant Council.
  • Anderson, L. (2003). Aquatic weeds: Policy, prevention, and control. California Invasive Plant Council Symposium 2003. Kings Beach, California, CA.
  • Anderson, L., K. Zaremba, et al. (2004). Aquatic working group. California Invasive Plant Council Symposium 2004. Ventura, California, CA.
  • Donaldson, S., W. West, et al. (2003). Getting the job done: Working within the regulatory environment at Lake Tahoe to manage weeds. California Invasive Plant Council Symposium 2003. Kings Beach, CA.
  • Donaldson, S. G. (1997). Flood-borne noxious weeds: Impacts on riparian areas and wetlands. California Exotic Pest Plant Council Symposium '97. Concord, CA.

Cal-IPC News Articles

  • Stack, L. B. (2009). Chasing weeds from Maine to California. Cal-IPC News. 16: 10,12.
  • Donaldson, S. (2003). Fighting weeds in the Tahoe basin. CalEPPC News. 11: 7.