Myriophyllum spicatum

Myriophyllum spicatum_spike watermilfoil_John Madsen_cropped
Photo: John Madsen

Common names: spike watermilfoil, Eurasian watermilfoil

Myriophyllum spicatum (spike watermilfoil) is a common submersed aquatic perennial (family Haloragaceae). Spike 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?

CDFA Rating: None?


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.

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

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.

Other Myriophyllum spicatum Information

  • 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.
  • 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.
  • Additional photos

    Myriophyllum spicatum_leaves and stems_ZoyaAkulova
    Myriophyllum spicatum (spike watermilfoil) leaves and stems. Photo: Zoya Akulova
    Myriophyllum spicatum_inflorescence_ZoyaAkulova
    Myriophyllum spicatum (spike watermilfoil) inflorescence. Photo: Zoya Akulova
    Myriophyllum spicatum_growth habit_ZoyaAkulova
    Myriophyllum spicatum (spike watermilfoil) growth habit. Photo: Zoya Akulova