''Myriophyllum spicatum'' (Eurasian watermilfoil or spiked water-milfoil) is a submerged

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

aquatic plant Aquatic plants, also referred to as hydrophytes, are vascular plants and Non-vascular plant, non-vascular plants that have adapted to live in aquatic ecosystem, aquatic environments (marine ecosystem, saltwater or freshwater ecosystem, freshwater ...

which grows in still or slow-moving water. Eurasian watermilfoil is native to

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

, and

North Africa North Africa (sometimes Northern Africa) is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region. However, it is sometimes defined as stretching from the Atlantic shores of t ...

, but has a wide geographic and climatic distribution among some 57 countries, extending from northern

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

. It is considered to be a highly

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

Description

Eurasian watermilfoil has slender stems up to long. The submerged

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

(usually between 15–35 mm long) are borne in pinnate whorls of four, with numerous thread-like leaflets roughly 4–13 mm long. Plants are

monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system comparable with gynomonoecy, andromonoecy and trimonoecy, and contras ...

with

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

s produced in the leaf axils (male above, female below) on a spike 5–15 cm long held vertically above the water surface, each flower is inconspicuous, orange-red, 4–6 mm long. Eurasian watermilfoil has 12–21 pairs of leaflets while northern watermilfoil ''M. sibiricum'' only has 5–9 pairs. The two can hybridize and the resulting hybrid plants can cause taxonomic confusion as leaf characters are intermediate and can overlap with parent species.

Chemistry

''Myriophyllum spicatum'' produces ellagic, gallic and

pyrogallic acid Pyrogallol is an organic compound with the formula C6H3(OH)3. It is a water-soluble, white solid although samples are typically brownish because of its sensitivity toward oxygen. It is one of three isomers of benzenetriols. Production and reac ...

s and (+)-

catechin Catechin is a flavan-3-ol, a type of secondary metabolite providing antioxidant roles in plants. It belongs to the subgroup of polyphenols called flavonoids. The name of the catechin chemical family derives from ''catechu'', which is the tannic ...

, allelopathic polyphenols inhibiting the growth of blue-green alga ''

Microcystis aeruginosa ''Microcystis aeruginosa'' is a species of freshwater cyanobacteria that can form harmful algal blooms of economic and ecological importance. They are the most common toxic cyanobacterial bloom in eutrophic fresh water. Cyanobacteria produce neu ...

''.Myriophyllum spicatum-released allelopathic polyphenols inhibiting growth of blue-greenalgaeMicrocystis aeruginosa. Satoshi Nakai, Yutaka Inoue, Masaaki Hosomi and Akihiko Murakami, Water Research, Volume 34, Issue 11, 1 August 2000, Pages 3026–3032,

Distribution

''Myriophyllum spicatum'' is found in disperse regions of

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

, and

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

Invasive species

Introduced areas

''Myriophyllum spicatum'' was likely first introduced to

in the 1940s where it has become an

in some areas. By the mid 1970s, watermilfoil had also covered thousands of hectares in British Columbia and Ontario, Canada, and spread some downstream via the

Columbia River The Columbia River (Upper Chinook language, Upper Chinook: ' or '; Sahaptin language, Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river headwater ...

system into the

Pacific Northwest The Pacific Northwest (PNW; ) is a geographic region in Western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though no official boundary exists, the most common ...

of the United States.

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

n watermilfoil is now found across most of Northern America where it is recognized as a noxious weed.

Impact

In lakes or other aquatic areas where native aquatic plants are not well established, the Eurasian watermilfoil plant can spread quickly. Eurasian watermilfoil has been known to crowd out native plants and create dense mats that interfere with recreational activity. Dense growth of Eurasian milfoil can also have a negative impact on fisheries by creating microhabitats for juvenile fish and obstructing space for larger fish, ultimately disrupting normal feeding patterns. Due to the Eurasian milfoil plant's inability to provide the same microhabitat for invertebrates created by native aquatic plant species, densely populated areas of Eurasian milfoil create an ecosystem with fewer food sources for the surrounding fish. Dense Eurasian milfoil growth can also create hypoxic zones by blocking out sun penetration to native aquatic vegetation, preventing them from photosynthesizing. Eurasian watermilfoil grows primarily from broken off stems, known as shoot fragments, which increases the rate at which the plant can spread and grow. In some areas, the Eurasian Watermilfoil is an Aquatic Nuisance Species. Eurasian watermilfoil is known to hybridize with the native northern watermilfoil (''M. sibiricum'') and the hybrid taxon has also become invasive in North America. This hybridization has been observed across the upper midwestern United States (Indiana, Minnesota, Michigan, Wisconsin) and in the Northwest (Idaho, Washington).

Control and management

It is impossible to completely eradicate the species once Eurasian watermilfoil is established. As a result, removal must be done to reduce an infestation to levels affordably controlled, with continued maintenance thereafter. Effective management techniques include insect biocontrol and hand-harvesting of the plant. The aquatic moth '' Acentria ephemerella'', the water veneer moth, feeds upon and damages this water milfoil. It has been used as an agent of

biological pest control Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, parasitism, herbivory, or ot ...

against the plant in North America. The milfoil weevil (''

Euhrychiopsis lecontei ''Euhrychiopsis lecontei'', also known as the milfoil weevil, is a type of weevil that has been investigated as a potential biocontrol agent for Eurasian water milfoil. It is found in the eastern and central United States and western Canada. Li ...

'') has also been used as biocontrol. Another method for biocontrol is

Grass Carp The grass carp (''Ctenopharyngodon idella'') is a species of large herbivorous freshwater fish in the family Cyprinidae, native to the Pacific Far East, with a native range stretching from northern Vietnam to the Amur River on the Sino-Russian ...

, (one of the Asian Carp species) which have been bred as

sterile Sterile or sterility may refer to: *Asepsis, a state of being free from biological contaminants * Sterile (archaeology), a sediment deposit which contains no evidence of human activity *Sterilization (microbiology), any process that eliminates or ...

and is sometimes released into affected areas. These fish primarily feed on aquatic plants and have proven effective at controlling the spread. However, the carp prefer many native species over the milfoil and will usually decimate preferred species before eating the milfoil. In Washington State the success rate of Grass Carp has been less than expected, where they were used in 98 lakes, and 39 percent of them had no submerged plant life left after only a short time. Hand-harvesting of invasive milfoils has shown much success as a management technique since around 2000. Several organizations in the New England states have undertaken large scale, lake-wide hand-harvesting management programs with extremely successful results. Well trained divers with proper techniques have been able to effectively control and then maintain many lakes, especially in the Adirondack Park in Northern New York where chemicals, mechanical harvesters, and other disruptive and largely unsuccessful management techniques are banned. After only three years of hand harvesting in Saranac Lake the program was able to reduce the amount harvested from over 18 tons to just 800 pounds per year. In order to prevent damages from mass growth of the plant in lakes, the water level can be lowered. By freezing out the bottom of the bank in the winter months, the population of the plant decreases.

Spread prevention

Trailering boats has proven to be a significant vector by which Eurasian milfoil is able to spread and proliferate across otherwise disconnected bodies of water. Effective methods for mitigating this spread include visual inspections with subsequent hand removal and pressure washing upon boat removal. In the Okanagan River Basin of south-central

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

, a specially-adapted

rototiller A cultivator (also known as a rotavator) is a piece of agricultural equipment used for secondary tillage. One sense of the name refers to frames with ''teeth'' (also called ''shanks'') that pierce the soil as they are dragged through it li ...

is used to

dredge Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features; reshaping land and water features to alter drainage, navigability, and commercial use; constructing ...

shallow water to damage or destroy the root system.

References

External links

*
Species Profile- Eurasian Watermilfoil (''Myriophyllum spicatum'' L.)
National Invasive Species Information Center,

United States National Agricultural Library The United States National Agricultural Library (NAL) is one of the world's largest agricultural research libraries, and serves as a national library of the United States and as the library of the United States Department of Agriculture. Locate ...

. Lists general information and resources for Eurasian Watermilfoil.
Flora Europaea: ''Myriophyllum spicatum''Flora of Taiwan: ''Myriophyllum spicatum''
*
Invading Species.com
Ontario Ministry of Natural Resources and the Ontario Federation of Anglers and Hunters
Jepson Manual Treatment
* USDA ARS
Photo gallery
{{Taxonbar, from=Q158130 spicatum Flora of Lebanon Plants described in 1753 Taxa named by Carl Linnaeus