Eurasian water-milfoil
Myriophyllum spicatum L.

SOURCE: The following information on this species is taken, in part, from the Plant Conservation Alliance, Alien Plant Working Group, Weeds Gone Wild website, Fact Sheets. The Fact Sheet information for this species can be found at http://www.nps.gov/plants/alien/factmain.htm. Modifications include additional pictures (from www.invasives.org) and resource information. Species management and control information is provided elsewhere. Check the website link provided to check for future updates. The last update for this fact sheet is April 2004.

NATIVE RANGE: Eurasia and Africa

DESCRIPTION: Eurasian watermilfoil, also called spike watermilfoil, is an emergent, herbaceous aquatic plant. Stems grow to the water surface, usually extending 3 to 10, but as much as 33, feet in length and frequently forming dense mats. Stems of Eurasian milfoil are long, slender, branching, hairless, and become leafless toward the base. New plants may emerge from each node (joint) on a stem, and root upon contact with mud.

Photo: Alison Fox, University of Florida, www.invasive.org

 

Photo: Leslie J. Mehrhoff, Univ. of Connecticut, IPANE, http://invasives.eeb.uconn.edu/ipane

ECOLOGICAL THREAT: Eurasian milfoil can form large, floating mats of vegetation on the surface of lakes, rivers, and other water bodies, preventing light penetration for native aquatic plants and impeding water traffic. The plant thrives in areas that have been subjected to various kinds of natural and manmade disturbance.

Photo: Robert L. Johnson, Cornell University, www.invasive.org.

DISTRIBUTION IN THE UNITED STATES: Watermilfoil occurs in thirty-three states east of the Mississippi River and has recently been found in Colorado. It is abundant in the Chesapeake Bay, the tidal Potomac River, and several Tennessee Valley reservoirs. Click here to see another distribution map.

HABITAT IN THE UNITED STATES: Typical habitat for Eurasian watermilfoil includes fresh to brackish water of fish ponds, lakes, slow-moving streams, reservoirs, estuaries, and canals.. It is tolerant of many water pollutants. Eurasian watermilfoil tends to invade disturbed areas where native plants cannot adapt to the alteration. It does not spread rapidly into undisturbed areas where native plants are well established. By altering waterways, humans have created a new and unnatural niche where milfoil thrives.

BACKGROUND: Eurasian watermilfoil was accidentally introduced from Eurasia in the 1940s. Two theories exist as to how it entered North America: (1) it escaped from an aquarium, or (2) it was brought in attached to commercial or private boats. A resort owner is thought to have introduced watermilfoil into the Tennessee Valley Authority reservoir system in 1953.

BIOLOGY & SPREAD: Most regeneration of Eurasian watermilfoil is from rhizomes, fragmented stems, and axillary buds that develop throughout the year. Flower spikes often remain above water until pollination is complete, then resubmerge. Although seeds are usually viable, they are not an important means of dispersal.

For more information on Eursian watermilfoil, please contact:
Al Cofrancesco, U.S. Army Corps of Engineers (cofrana@ex1.wes.army.mil)
Center for Aquatic and Invasive Plants, University of Florida and Sea Grant - Non- Native Invasive Aquatic Plants in the United States - http://plants.ifas.ufl.edu/seagrant/myrspi2.html#hpcontrol
Delaware River Invasive Plant Partnership - Invasive Plant Fact Sheets - http://www.paflora.org/Invasive%20species%20fact%20sheets.htm - prepared by: Ann F. Rhoads and Timothy A. Block, Morris Arboretum of the University of Pennsylvania - April 2000.
Invasive Plant Atlas of New England - University of Connecticut http://webapps.lib.uconn.edu/ipane/browsing.cfm?descriptionid=78
Ken Langeland, University of Florida Institute of Food and Agriculture (kal@gnv.ifas.ufl.edu)
Kris Johnson, Great Smoky Mountains National Park, Gatlinburg TN
Ohio Department of Natural Resources - Invasive Plant Fact Sheets - http://www.dnr.state.oh.us/dnap/invasive/12milfoil.htm - January 8, 2003
Plant Invaders of Mid-Atlantic Natural Areas, National Park Service and U.S. Fish and Wildlife Service, http://www.invasive.org/eastern/midatlantic/mysp.html
Southeast Exotic Pest Plant Council, Invasive Plant Manual, SE-EPPC http://www.se-eppc.org/manual/watermilfoil.html
Van Driesche, R., et al., 2002, Biological Control of Invasive Plants in the Eastern United States, USDA Forest Service Publication FHTET-2002-04, 413 p. http://www.invasive.org/eastern/biocontrol/6EurasianMilfoil.html.
Virginia Natural Heritage Program Fact Sheet-Eurasian watermilfoil -http://www.dcr.virginia.gov/dnh/fsmysp.pdf
Wisconsin Department of Natural Resources - Invasive Plant Fact Sheets - Eurasian Water-milfoil -http://www.dnr.state.wi.us/org/land/er/invasive/factsheets/milfoil.htm - September 3, 2004.

SUGGESTED ALTERNATIVE PLANTS: SUGGESTED ALTERNATIVE PLANTS: Yellow nelumbo (Nelumbo lutea), pond weed (Potamogeton nodosus), butterweed (Senecio glabellus) are some alternative plants to consider for the eastern U.S.
AUTHORS: Tom Remaley, Great Smoky Mountains National Park, Gatlinburg, TN. EDITORS: Jil M. Swearingen, U.S. National Park Service, Washington, DC. Alison A. Dalsimer, Consultant, Legacy Resource Management Program, Washington, D.C.
REFERENCES: B.C. Ministry of Environment 1989. Eurasian Water Milfoil in British Columbia (Pamphlet). Gleason, H.A., A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. 2nd ed. The New York Botanical Garden, 910.

Plant Conservation Alliance, Alien Plant Working Group.

Management and Control Information

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