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.

Cal-IPC Rating: High

Cal-IPC Assessment

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.

Cal-IPC Newsletter Articles

Cal-IPC 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.

Other Myriophyllum spicatum Information

  • CalPhotos - Images of plants taken mostly in California.
  • CalFlora - Distribution information based on submitted observations and herbarium specimens.
  • 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.