MYRIOPHYLLUM SPICATUM L.
Eurasian water-milfoil; spike water-milfoil
pronounced: mirio-file-um / spi-ka-tum
from: myrios (G.): numberless
phyllon (G.): leaf
spica (L.): spike
"a plant with many leaf divisions, and a spike of flowers"
is submersed. It tolerates a wide range of
conditions, and often forms large infestations.
Eurasian water-milfoil stems are reddish-brown to whitish-pink. They are branched and
commonly grow to lengths of six to nine feet. The leaves are deeply divided,
soft and feather-like. Leaves are about two inches long. The leaves are arranged in whorls of
three to six leaves about the stem. The flowers of Eurasian water-milfoil
reddish and very small. They are held above the water on an emersed flower spike that is several
- Eurasian water-milfoil is a submersed, rooted, perennial
- its stems can "top out" in 20 feet of water, but the plant is most often found in water 0.5 to
3.5 m deep (Aiken et al. 1979)
- often forms large infestations; often is the most abundant submersed species in a locale
- spreads and reproduces mainly by regrowth of plant fragments; spreads locally by stolons
- will halt boat traffic on rivers; will fill a lake surface from shore to shore
- an aquatic weed worldwide
- seems to prefer lakes, ponds and slow-moving rivers and streams but can also grow in
fast-moving water (Newroth 1985)
- tolerates a wide range of water conditions, including spring water and even brackish water of
tidal creeks and bays with salinity of up to 10 parts per thousand (Beaven 1960)
- temperature tolerance: Eurasian water-milfoil is winter-hardy, able to overwinter in frozen
lakes and ponds in northern states and Canada; but is also able to grow in shallow, over-heated
bays such as Chassahowitzka Bay in Florida
Myriophyllum spicatum L.
Original description: Linnaeus 1753
- dicot, perennial
- there are a number of water-milfoils, native and non-native, that are confusable; this
water-milfoil has decidedly feathery-looking leaves
- plants submersed rooted, attached to the
- stems slender, smooth, 6 to 20 ft. long; stems reddish-brown to
branching several times near the water surface
- leaves are olive-green, less than 2 in. long,
soft, deeply divided, feather-like; each leaf with a central axis (midrib) and 14 to 24 or so very
slender (filiform) segments on each side of the axis
- leaf whorls are arranged along the stems in whorls of 3 to 6 (usually 4)
leaves; whorl nodes are about 3/8 in. apart
- flowers on an emersed spike, held erect above
the water, the spike to 8 inches long; flowers reddish; arranged in 4-flowered whorls along spike; petals 4; petals 1/8 in. long; sepals 4;
stamens 8; flowering in Canada from late July to early August
- fruit 4-lobed; splitting into 4 nutlets
- roots fibrous; often developing on plant fragments
Myriophyllum spicatum might be confused with a number of other
submersed plants, including other water-milfoils and other submersed plants.
- native northern water-milfoil (Myriophyllum
sibiricum = M. exalbescens):
-- has fewer than 12 leaf segments on each side of the leaf axis, whereas Eurasian
water-milfoil leaves have 14 or more leaf segments on each side of the leaf axis; and has
stouter stems than does Eurasian water-milfoil
- native coontail (Ceratophyllum demersum):
-- leaves are toothed and the plant feels rough when pulled through the hand, whereas
Eurasian water-milfoil leaves are not toothed and the plant does not feel rough
How it got here:
- Myriophyllum spicatum, Eurasian water-milfoil was probably
intentionally introduced, possibly by federal authorities, into the U.S. and was first found in 1942
in Washington, D.C. (Couch & Nelson 1985); or the plant was introduced in the late 1800s,
possibly in ship ballast, in the Chesapeake Bay area (Aiken et al. 1979)
- may have been spread as packing material for worms sold to fishermen in Oklahoma (Couch
& Nelson 1985)
- was first observed in Ontario in the 1960s; was first observed in British Columbia in 1970 in
- first found in Minnesota in Lake Minnetonka, in 1987; by 1990 it was in 37 waterbodies; by
1991, 51; and in 1999 was found in 100 waterbodies (R.M. Newman, pers. com.)
- Eurasian water-milfoil is not on the U.S. Federal Noxious Weed List; it continues to be sold
through aquarium supply dealers and over the Internet.
Potential to spread elsewhere in U.S.:
- Eurasian water-milfoil is being spread by transport of fragments from one
water body to another, both by boats and other vehicles and by water currents (Aiken et
- Minnesota authorities found aquatic plants on 23% of all boats and trailers inspected
- it is also cold hardy and tolerant of a variety of water quality conditions
- Myriophyllum spicatum grows quickly to form dense infestations
shade out and replace native plants (Smith & Barko 1990; Madsen 1994; Madsen et
- Eurasian water-milfoil infestations negatively affect birds and fish (Aiken et al. 1979; Madsen et al. 1995)
- decaying mats of Eurasian water-milfoil reduce oxygen levels in the water (Honnell 1992)
Due to decades of university, state and federal research and experience with Myriophyllum spicatum in the U.S. and Canada, several methods have been
developed to help in its management.
the use of mechanical harvestors and chopping machines should be carefully
considered because resulting plant fragments may easily regrow or be carried downstream to
create new infestations; harvesting machines are effective at reducing a large biomass in a short
time, however harvesting may have to be done several times per year
In Okanagan Lake, British Columbia, authorities have apparently successfully experimented with
management by simultaneously rototilling plants and roots and underwater vacuuming (Newroth 1988)
Water level manipulation (drawdown) has been used effectively to control
Eurasian water-milfoil in Tennessee reservoirs (Bates et al. 1985)
years of research to find insect
biocontrols has resulted in the successful introduction of insects which are
believed to be helping keep Eurasian water-milfoil under control; biocontrol
fish also have been successfully used (Bonar et al. 1993.)
registered aquatic herbicides such as endothall, 2,4-D and fluridone do
temporary control of Eurasian water-milfoil, but efforts to eradicate the plant "are rarely, if ever,
likely to succeed" (Smith & Barko 1990)
From the University of Florida Aquatic Weed Management Guide, Vandiver 1999:
According to this Guide, a number of aquatic herbicides may be used to manage
"watermilfoil", including formulations of endothall, diquat, copper, 2,4-D, and fluridone. A
concentration of 5 ppm 2,4-D for 1 h will kill all plants (Steward & Nelson 1972). As always,
comply with federal law by following the herbicide
label instructions, permissible sites and application rates.
What can you do?
Transporting Eurasian water-milfoil fragments on boats, trailers, and in livewells
the main introduction route to new lakes and rivers. So, clean your
boat before you leave the ramp!
But, there's plenty more you can do to help.
Laws and lists:
- is "state-listed" in Florida, Minnesota, North Carolina, South Carolina and
- is on the Florida Prohibited Plants list, Florida Department of Environmental
- is on lists of government agencies and/or pest plant councils in 21 states
- is on the Florida Exotic Pest Plant Council list:
Category II - "species that have shown a potential to disrupt native plant communities in
Want to know more?
The information contained on this wep page was extracted from
published scientific literature and agency reports. It is important to know that plant research, like most
areas of scientific research, is still relatively young and incomplete--much may have been
published about the physiology of one plant but not about its management; much may have been
published about how to culture and grow another plant but not about its natural ecology.
Thousands of research articles may have been published about one invasive plant, but perhaps
only a dozen about another.
If you want to read the research yourself, perhaps to clarify or expand an area of information
contained here, or to help determine your own line of research, you are welcome to query the
world's largest collection of international scientific literature about aquatic, wetland and invasive
plants, the APIRS bibliographic database, which contains more than 54,000 citations and their content
keywords. Or you might want to ask us to do
it for you and mail or e-mail the search results to you.
This is the literature about Myriophyllum spicatum that was used to
develop this web page. More research items about this plant may be found at APIRS:
- Aiken SG, Newroth PR, Wile I. 1979. The biology of
weeds. 34. Myriophyllum spicatum L. Canadian J. Plant Sci. 59:201-215
- Barko JW. 1983. The growth of Myriophyllum spicatum in
relation to selected characteristics of sediment and solution. Aquatic Botany 15:91-103
- Bates AL, Smith CS. 1994. Submersed plant invasions and declines in
southeastern United States. Lake and Reservoir Management 10(1):53-55
- Bertholdt W. 1958. Your aquarium needs Myriophyllum -- plant of
delicate beauty. Aquarium Journal 29:106-107
- Bonar SA, Thomas GL, Thiesfield SL, Pauley GB, Stables TB. 1993.
Effect of triploid grass carp on the aquatic macrophyte community of Devil's Lake, Oregon.
North American Journal Fisheries Management 13(4):757-765
- Bratager M, Crowell W, Enger S, Montz G, Perleberg D, Rendall WJ, Skinner L,
Welling CH, Wright D. 1996. Harmful Exotic Species of Aquatic Plants and WIld
Animals in Minnesota. Annual Report. Minnesota Department of Natural Resources, St. Paul.
- Budd J, Lillie RA, Rasmussen P. 1995. Morphological characteristics of
the aquatic macrophyte, Myriophyllum spicatum L. in Fish LAke, Wisconsin.
of Freshwater Ecology 10:19-31
- Couch R, Nelson E. 1985. Myriophyllum spicatum in North
America. In: Anderson LWJ, ed., First International Symposium on Watermilfoil
Related Haloragaceae Species, 23-24 July 1985, Vancouver, BC. Aquatic Plant Management
Society, Vicksburg, MS.
- Creed RP. 2000. The weevil-watermilfoil interaction at different spatial
scales: what we know and what we need to know. J. Aquat. Plant Manage. 38:78-81
- Creed RP, Sheldon SP. 1995. Weevils and watermilfooil: did a North
American herbivore cause the decline of an exotic plant? Ecological Applications 5:1113-1121
- Engel S. 1995. Eurasian watermilfoil as a fishery management tool.
- Fernald ML. 1919. Two new Myriophyllums and a species new to the
United States. Rhodora 21:120-124
- Goldsby TL, Bates AL, Stanley RA. 1978. Effect of water level
fluctuation and herbicide on Eurasian watermilfoil in MElton Hill Reservoir. Journal of Aquatic
Plant Management 16:34-38
- Holm LG, Plucknett DL, Pancho JV, Herberger JP. 1977. The
world's worst weeds: distribution and biology. Honolulu: University Press of Hawaii. 609 pp.
- Honnell D, Madsen JD, Smart RM. 1992. Effects of aquatic plants on
water quality in pond ecosystems. In: Proceedings, 26 Annual Meeting, Aquatic
Plant Control Research Program, Report A-92-2. US Army Corps of Engineers Waterways
Experiment Station, Vicksburg, MS.
- Johnson RL, Van Dusen PJ, Toner JA, Hairston NG. 2000. Eurasian
watermilfoil biomass associated with insect herbivores in New York. J. Aquat. Plant Manage.
- Keast A. 1984. The introduced aquatic macrophyte, Myriophyllum
spicatum, as habitat for fish and their macroinvertebrate prey. Can. J. Zool. 62:1289-1303
- Lillie RA. 2000. Temporal and spatial changes in milfoil distribution and
biomass associated with weevils in Fish Lake, WI. J. Aquat. Plant Manage. 38:98-104
- McCann JA et al. 1996. Nonindigenous aquatic and selected terrestrial
species of Florida-Status, pathway, and time of introduction, present distribution, and significant
ecological and economic effects. Southeastern Biological Science Center, Gainesville, 256 pp.
- Madsen JD, Smart RM, Dick GO, Honnell DR. 1995. The influence of
an exotic submersed aquatic plant, Myriophyllum spicatum, on water quality,
vegetation and fish populations of Kirk Pond, Oregon. In: Proceedings, 29 Annual
Meeting, Aquatic Plant Control Research Program, US Army Corps of Engineers Waterways
Experiment Station, Vicksburg, MS.
- Nelson LS. 1996. Growth regulation of Eurasian watermilfoil with
flurprimidol. Journal of Plant Growth Regulation 15:33-38
- Newman RM, Biesboer DD. 2000. A decline of Eurasian watermilfoil in
MInnesota associated with the milfoil weevil, Euhrychiopsis lecontei 2000. J.
Plant Manage. 38:105-111.
- Nichols SA, Buchan LA. 1997. Use of native macrophytes as indicators
suitable Eurasian watermilfoil habitat in Wisconsin lakes. Journal of Aquatic Plant Management
- Sheldon SP. 1994. Invasions and declines of submersed macrophytes in
New England, with particular reference to Vermont lakes and herbivorous invertebrates in New
England. Lake and Reservoir Management 10(1):13-17
- Smith CG, Barko JW. 1990. Ecology of Eurasian watermilfoil. Journal
of Aquatic Plant Management 28:55-64
- Smith CG, Barko, JW. 1996. Evaluation of a Myriophyllum
spicatum decline in reservoirs of the Tennessee and Cumberland rivers. Tech. Report
A-96-6, US Army Corps of Engineers Waterways Experiment Station, Vicksburg, MS
- Solarz SL, Newman RM. 1996. Oviposition specificity and behavior of
the watermilfoil specialist Euhrychiopsis lecontei. Oecologia 106:337-344
- Steward KK, Nelson LL. 1972. Evaluations of controlled release PVC
and Attaclay formulations of 2,4-D on Eurasian watermilfoil. Hyacinth Control J. 10:35-37
- Stuckey RL, Moore DL. 1995. Return and increase in abundance of
aquatic flowering plants in Put-in-Bay Harbor, Lake Erie, Ohio. Ohio J. Sci. 95(3):261-266
- Vandiver VV. 1999. Florida aquatic weed management guide. Univ. of
FL, IFAS, Cooperative Extension Service, Publ. SP-55, 130 pp.
- Verma U, Charudattan R. 1993. Host range of Mycoleptodiscus
terrestris, a microbial herbicide candidate for Eurasian watermilfoil, Myriophyllum
spicatum. Biological Control 3:271-280
Other web sites that treat Eurasian water-milfoil:
|| This web page was authored in June, 2001, by Victor Ramey (Center for Aquatic and Invasive Plants, University of Florida), with significant contribution from Barbara Peichel (Sea Grant, University of Minnesota). The information contained herein is based on the literature found in the APIRS database.