Elodea canadensis (Canadian pondweed)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- History of Introduction and Spread
- Habitat List
- Biology and Ecology
- Latitude/Altitude Ranges
- Air Temperature
- Water Tolerances
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Economic Impact
- Environmental Impact
- Social Impact
- Risk and Impact Factors
- Uses List
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Elodea canadensis Rich. in Michx. (1803)
Preferred Common Name
- Canadian pondweed
Other Scientific Names
- Anacharis alsinastrum Bab.
- Anacharis canadensis (Michx.) Planch.
- Elodea ioensis Wylie
- Elodea planchonii Casp.
- Udora canadensis (Michx) Nutt.
International Common Names
- English: American duckweed; Canadian elodea; Canadian waterweed; common elodea; ditch weed; elodea; oxygen weed; water thyme; waterweed
- Spanish: broza del Canada
- French: elodee du Canada
- Portuguese: estrume-novo
Local Common Names
- Cuba: elodea
- Germany: Kanadische Wasserpest
- Italy: elodea; peste d'acqua
- Japan: kanadamo
- Netherlands: waterpest
- South Africa: Kanadese waterpes
- Sweden: vattenpest
- ELDCA (Elodea canadensis)
Summary of InvasivenessTop of page
E. canadensis is a submerged aquatic species of slower flowing rivers, native to North America. It has been intentionally introduced into areas outside of its native range as an ornamental aquarium species. This species has a wide ecological tolerance and grows relatively fast, but prefers neutral to calcareous open water that is not turbid or strongly affected by environmental influences such as water turbidity or wind fetch. E. canadensis is a perennial, overwintering in the deeper water, reproducing asexually. Disturbance increases the dispersal of numerous propagules and the vigorous re-growth is enhanced through changes in availability of nutrients. E. canadensis is considered a pioneer species, rapidly colonising new areas, however, it is often later replaced by other aquatic weeds such as E. nutallii. E. canadensis can form dense mats which can interfere with recreational activities, navigation and port infrastructure. In addition to this, the dense mats outcompete native plant species and therefore decrease the biodiversity in an area. It also accentuates the accumulation of finer and organic silts which enhances its growth further as nutrients are released. Control of this species is complicated and loss of fragments should be minimised to prevent further spread. E. canadensis is considered a serious weed in Australia and as a principal weed in Denmark, England, Germany, Italy, New Zealand, The Netherlands, Norway, Poland, Sweden and parts of the USA.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Monocotyledonae
- Order: Hydrocharitales
- Family: Hydrocharitaceae
- Genus: Elodea
- Species: Elodea canadensis
Notes on Taxonomy and NomenclatureTop of page
Historically there has been much confusion in the classification of the species of the genus Elodea (Family Hydrocharitaceae). However, Cook and Urmi-König (1985), in the latest revision of the genus, recognise five species of Elodea, all of them from the New World: E. potamogeton (Bert) Espinosa and E. callitrichoides (Rich.) Caspary are endemic to South America, while E.bifoliata St. John, E. canadensis and E. nuttallii grow in North America.
The name E. canadensis Michx. is universally accepted for this common, widespread waterweed. Four varieties are recognised by Missouri Botanical Gardens (2014), var. angustifolia (Muhl.) Farw., var. gigantea Hort. In Bailey, var. latifolia (Casp.) Asch. & Graebn and var. planchonii Farw. ITIS (2014), however, does not recognise any of these.
DescriptionTop of page
E. canadensis is a dioecious, perennial, submerged aquatic macrophyte with elongated flexuous stems and long internodes which are clothed with whorls of sessile, minutely-serrate leaves and rooted from their nodes typically in mud substrates. The middle and upper leaves, typically three per whorl, are elliptic, approximately 2-5 mm wide; leaves in the upper whorls grow closely together. In autumn, turions or short densely-leaved resistant stems develop then break off to float around the waterbody before they sink to the bottom where they rest until they regrow in spring. Male flowers are pedunculate by the elongate, filiform base of the floral tube, not released from the plant at anthesis; sepals 3.5-5.0 mm long, petals 5 mm long. The staminate spathe has a pedunculate base, inflated, 7 mm long, 4 mm wide. The female flower stalk is approximately 15 cm long; sepals and petals 2-3 mm long. Petals white. Pistillate spathe cylindrical. Female flowers are common, male flowers are absent in Europe and apparently rare elsewhere. Seed buds mostly without stems, sometimes with short stems and seeds are glabrous.
DistributionTop of page
E. canadensis originates from North America, but now occurs throughout the USA. The plant was introduced to the UK in the mid-1800s and has spread eastwards in Western Europe with the apparent exception, so far, of Iberia and northern Scandinavia. It is widespread in Australia and New Zealand, but has, so far, been recorded in only a few Asiatic countries.
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|China||Present||Introduced||Holm et al., 1979; Lia et al., 2009|
|India||Present||Introduced||Holm et al., 1979; Q-bank, 2014|
|Malaysia||Present||Introduced||Revilla et al., 1991|
|Saudi Arabia||Present||Introduced||Mohamed and Al-Shehri, 2010|
|Singapore||Present||Introduced||Revilla et al., 1991|
|Thailand||Present||Introduced||Revilla et al., 1991|
|Egypt||Present||Introduced||Holm et al., 1979|
|Mauritius||Present||Introduced||Holm et al., 1979|
|South Africa||Widespread||Introduced||Spicer and Catling, 1988; Invasive Species South Africa, 2014|
|Canada||Present||Present based on regional distribution.|
|-Alberta||Widespread||Native||Haag, 1979; Spicer and Catling, 1988; Alberta Biodiversity Monitoring Institute, 2014|
|-British Columbia||Widespread||Spicer and Catling, 1988; E-Flora, 2014|
|-Manitoba||Widespread||Godfrey and Wooten, 1997|
|-New Brunswick||Present||USDA-NRCS, 2014|
|-Nova Scotia||Present||USDA-NRCS, 2014|
|-Ontario||Widespread||Spicer and Catling, 1988|
|-Quebec||Widespread||Spicer and Catling, 1988|
|-Saskatchewan||Widespread||Godfrey and Wooten, 1997|
|Mexico||Present||Holm et al., 1979; USDA-NRCS, 2014|
|USA||Present||Present based on regional distribution.|
|-Alabama||Widespread||Native||Godfrey and Wooten, 1997|
|-Alaska||Present||Native||Alaska Plant Materials Center, 2014; USDA-NRCS, 2014|
|-Arizona||Widespread||Native||Godfrey and Wooten, 1997|
|-Arkansas||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Colorado||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Connecticut||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Delaware||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Florida||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Hawaii||Present||Native||Holm et al., 1979|
|-Idaho||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Illinois||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Indiana||Widespread||Native||Willey et al., 1974|
|-Kansas||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Kentucky||Widespread||Westerdahl and Getsinger, 1988|
|-Louisiana||Widespread||Westerdahl and Getsinger, 1988; Aquatic plant species in Louisiana, 2014|
|-Maine||Widespread||Native||Godfrey and Wooten, 1997|
|-Maryland||Widespread||Godfrey and Wooten, 1997|
|-Michigan||Widespread||Native||Nichols et al., 1989|
|-Minnesota||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Mississippi||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Missouri||Widespread||Westerdahl and Getsinger, 1988|
|-Montana||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Nebraska||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Nevada||Widespread||Native||Westerdahl and Getsinger, 1988|
|-New Hampshire||Widespread||Native||Westerdahl and Getsinger, 1988|
|-New Jersey||Widespread||Native||Westerdahl and Getsinger, 1988|
|-New Mexico||Widespread||Native||Godfrey and Wooten, 1997|
|-New York||Widespread||Native||Peverly and Johnson, 1979; Peverly and Kopka, 1991|
|-North Carolina||Widespread||Native||Westerdahl and Getsinger, 1988|
|-North Dakota||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Ohio||Widespread||Native||Quinn et al., 1977|
|-Oklahoma||Widespread||Godfrey and Wooten, 1997|
|-Oregon||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Pennsylvania||Widespread||Native||Godfrey and Wooten, 1997|
|-Rhode Island||Widespread||Native||Westerdahl and Getsinger, 1988|
|-South Carolina||Widespread||Westerdahl and Getsinger, 1988|
|-South Dakota||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Tennessee||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Texas||Widespread||Westerdahl and Getsinger, 1988|
|-Utah||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Vermont||Widespread||Native||Westerdahl and Getsinger, 1988|
|-Virginia||Widespread||Native||Godfrey and Wooten, 1997|
|-West Virginia||Widespread||Native||Godfrey and Wooten, 1997|
|-Wyoming||Widespread||Native||Westerdahl and Getsinger, 1988|
Central America and Caribbean
|Belize||Present||Holm et al., 1979|
|Cuba||Present||Introduced||Invasive||Oviedo Prieto et al., 2012|
|Puerto Rico||Present||Introduced||Holm et al., 1979|
|Argentina||Present||Introduced||Holm et al., 1979|
|Chile||Present||Introduced||Missouri Botanical Garden, 2008|
|Ecuador||Present||Introduced||Missouri Botanical Garden, 2008|
|Austria||Widespread||Introduced||Wychera et al., 1990|
|Czechoslovakia (former)||Widespread||Introduced||Adamec and Ondok, 1992|
|Finland||Present||Introduced||1884||Dandy, 1980; NOBANIS, 2014||Extremely common in southern and central Finland and still expanding its range|
|Germany||Present||Introduced||1859||Sculthorpe, 1971; Krausch, 1987; NOBANIS, 2014|
|Hungary||Widespread||Introduced||Keresztes and Horvath, 1977|
|Ireland||Widespread||Introduced||Sculthorpe, 1971; NOBANIS, 2014|
|Italy||Present||Introduced||Holm et al., 1979|
|Lithuania||Widespread||Introduced||1884||Stepanaviciene, 2000; NOBANIS, 2014|
|Netherlands||Widespread||Introduced||van Oostsroom, 1973; Best, 1979|
|Norway||Widespread||Introduced||1925||Rorslett, 1995; NOBANIS, 2014|
|Poland||Widespread||Introduced||1859||Dandy, 1980; NOBANIS, 2014|
|Russian Federation||Widespread||Introduced||Sculthorpe, 1971|
|-Central Russia||Present||Introduced||Dandy, 1980|
|-Russia (Europe)||Present||Introduced||1880||Dandy, 1980|
|-Siberia||Widespread||Introduced||Sculthorpe, 1971; Kozhova and Izhboldina, 1993|
|Spain||Widespread||Introduced||Palet et al., 1991|
|Sweden||Widespread||1871||Sculthorpe, 1971; NOBANIS, 2014|
|Switzerland||Widespread||Introduced||Sher-Kaul et al., 1995|
|UK||Widespread||Introduced||Sculthorpe, 1971||First reported in Scotland in 1854|
|Ukraine||Present||Introduced||Kharchenko et al., 2008|
|Yugoslavia (former)||Present||Introduced||Dandy, 1980|
|Australia||Widespread||Introduced||Mitchell, 1978; Burdon and, 1986; Royal Botanic Gardens Sydney, 2008|
|-New South Wales||Widespread||Introduced||Ripper Madin, 1984|
|-South Australia||Present||Introduced||Royal Botanic Gardens Sydney, 2008|
|New Zealand||Widespread||Introduced||Forsyth and Howard-Williams, 1983; Coffey and Clayton, 1987|
History of Introduction and SpreadTop of page
The following extract is taken from NOBANIS, (2011) - ‘Elodea canadensis was first observed in Europe in 1836, in an Irish pond, where it had already been established for some time. It has been introduced to a large number of European countries and was first reported in Scotland in 1854, in Germany near Berlin in 1859 and also in Poland at about this time. The first report of E. canadensis in Scandinavia is from Denmark in 1870, Sweden in 1871 and Finland in 1884. In Finland E. canadensis was intentionally planted in the Botanical Garden of the University of Helsinki (Hintikka 1917), from which it spread with water and birds to the entire country. Although E. canadensis was first observed in Norway near Oslo in 1925, it did not begin to spread to other areas until the 1960s. E. canadensis was observed for the first time in the European part of Russia in 1880, in Latvia in 1872, in Lithuania in1884 and in Estonia in 1905.’
The introduction of the closely related and invasive E. nuttallii into Europe resulted in the displacement of E. canadensis from many localities where it had become well established (Simpson, 1990; Thiébaut et al., 1997; Barrat-Segretain, 2001; Larson, 2007).
IntroductionsTop of page
|Introduced to||Introduced from||Year||Reason||Introduced by||Established in wild through||References||Notes|
|Natural reproduction||Continuous restocking|
|Australia||1876||Yes||Council of Heads of Australasian Herbaria (2014)||First recorded in Tasmania|
|New Zealand||1868||Aquaculture (pathway cause)||Yes||THOMSON (1922)|
HabitatTop of page
E. canadensis can grow in a range of habitats, but prefers quiet ponds, lakes and slow-moving water with a peaty or muddy silt substrates. E. canadensis is a common species in nutrient rich, or eutrophic, relatively quiet or slower water flows of many inland freshwater bodies (ponds, lakes, ditches, irrigation channels) and is often associated with organic-rich muds.
Habitat ListTop of page
|Terrestrial ‑ Natural / Semi-natural||Wetlands||Secondary/tolerated habitat||Productive/non-natural|
|Irrigation channels||Principal habitat||Harmful (pest or invasive)|
|Rivers / streams||Principal habitat||Productive/non-natural|
|Ponds||Principal habitat||Harmful (pest or invasive)|
Biology and EcologyTop of page
As exotic populations in Europe appear to only reproduce vegetatively, depending on the number of different introductions, the genetic diversity is likely to be small. Molecular studies are however, needed, however, to clarify this issue.
E. canadensis is an aggressively competitive weed, which spreads mainly by vegetative plant fragments, but also to some extent by seeds. Over-wintering buds and fragments of the brittle branches are easily detached by waves, currents, foraging animals and boat traffic. New roots develop quickly on the nodes of these fragments which are carried downstream to form new stands. This method of propagation gives E. canadensis a considerable advantage over annual species and resulted in its rapid spread throughout Europe following its introduction from North America (Holm et al., 1997; NOBANIS, 2011). Sexual reproduction in the field is believed to be very rare because of infrequent flowering and the differing abundance of the two sexes in nature. In Europe, only female flowers occur, making sexual reproduction impossible, so that spread occurs entirely by vegetative fragments. When both pistillate and staminate flowers are present at a site, the reproductive structures are pushed from the spathe, raised to the water surface by thread-like hypanthia and anthesis and pollination occur. At dehiscence the anthers open explosively and pollen is scattered over the water where it drifts to the stigmas.
Physiology and Phenology
Perennation is by densely leaved crowded apices or turions. During autumn, apices cease to elongate and come to bear tightly clustered dark green leaves, which contain much starch and are slightly more cuticularized than the normal foliage leaves. These apices may be liberated when the parent stems disintegrate and sink to the bottom, or remain attached throughout winter. The apices remain dormant until spring, when the leaves expand, adventitious roots develop from the lower nodes, the axis elongates and a new plant is formed. E. canadensis begins to grow during the spring season in temperate zones as the temperature rises to between 10-15°C. At ambient light levels, shoot biomass increases with temperature up to 28°C; root biomass shows an opposite tendency (Barko et al., 1982). Growth of this species is greatly stimulated under eutrophic conditions (Hughes, 1976; Barko and Smart, 1983; Kraush, 1987).
Erhard and Gross (2006) suggested that the production by both of allelochemicals that interfere with the growth of cyanobacteria and algae by E. canadensis and the closely related E. nuttallii could at least play some role in the success of these two species as invasives.
E. canadensis has a wide climatic tolerance, present from Alaska to Puerto Rico, though it may be less common as the extremes of its range, being predominant in temperate areas of North America and Europe. Pip and Simmons (1986) in Canada and Sheldon and Boylen (1977) in the USA, studied the maximum depths at which a number of submerged aquatic plants were found and the maximum recorded for any species was 12-14 m for Elodea. In North America it has been recorded in neutral to slightly alkaline inland waters and in fresh to slightly brackish coastal waters (Holm et al., 1997).
Riis et al. (2012), compared the effects of temperature and light availability on the growth and morphology of E. canadensis, Egeria densa and Lagarosiphon major and suggested that, in general, subject to variations due to timing of introductions, E. densa will dominate warmer, shallower waters, L. major will dominate in colder, clear-water lakes, whilst E. canadensis will continue its role as a pioneer species which is rapidly replaced by the two taller species after their arrival.
ClimateTop of page
|C - Temperate/Mesothermal climate||Preferred||Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C|
|Cf - Warm temperate climate, wet all year||Tolerated||Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year|
|Cs - Warm temperate climate with dry summer||Preferred||Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers|
|Cw - Warm temperate climate with dry winter||Preferred||Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)|
Latitude/Altitude RangesTop of page
|Latitude North (°N)||Latitude South (°S)||Altitude Lower (m)||Altitude Upper (m)|
Air TemperatureTop of page
|Parameter||Lower limit||Upper limit|
|Absolute minimum temperature (ºC)||-1||4|
Water TolerancesTop of page
|Parameter||Minimum Value||Maximum Value||Typical Value||Status||Life Stage||Notes|
|Conductivity (µmhos/cm)||200||1000||Optimum||2000 tolerated|
|Depth (m b.s.l.)||1||Optimum||3 (-12) tolerated|
|Dissolved oxygen (mg/l)||Optimum||metabolism creates range of 40-250%|
|Hardness (mg/l of Calcium Carbonate)||20||300||Optimum||<20 - >400 tolerated|
|Salinity (part per thousand)||0||Optimum||0.05 seawater tolerated|
|Velocity (cm/h)||0||700||Optimum||0-20 cm/sec|
|Water pH (pH)||7||8.5||Optimum||8.5-10 tolerated|
|Water temperature (ºC temperature)||10||25||Optimum||4-28 tolerated but probably temperature adaptive|
Notes on Natural EnemiesTop of page
The snails Lymnea peregra and Bithynia spp. are natural herbivores of E. canadensis. Populations of these species can expand enormously if not controlled by natural predators and under such circumstances snails can serve as a biological control agent. However, Pieczynska (2003) studied the damage inflicted on a population of E. canadensis by the snail L. stagnalis and concluded that although the snail caused a substantial reduction in biomass and severe damage to E. Canadensis, the plant fragments remaining after grazing showed a high capacity to regenerate new plants.
Means of Movement and DispersalTop of page
E. canadensis is spread locally downstream along rivers, streams and channels.
Pieces of fragment may become attached to water animals, mammals, fish or birds and transferred locally.
Accidental spread of E. canadensis may also occur via attachment of fragments to fishing nets or boats.
E. canadensis was intentionally introduced into countries outside of its native range as an ornamental aquarium species.
Pathway CausesTop of page
Pathway VectorsTop of page
Economic ImpactTop of page
Both E. canadensis and the closely related E. nuttallii have the potential to develop into dense submerged beds. This prevents the use of water for recreational and professional purposes (Larson, 2003), navigation and port infrastructure (CPS-SKEW, 2008). The plant can also clog and impede drainage waterways. Water flow in irrigation channels may slow and become blocked, reducing water supply to irrigation fed crops, such as rice in Asiatic countries and cotton in the USA. In Australia, Elodea is one of the main problems in 8000 km of canals and irrigation channels which feed the farm areas of Victoria (Bill, 1969). Mehta et al. (1973) reported that about 1500 ha of the Chambal irrigation system was infested with aquatic weeds, causing a reduction in the water carrying capacity by as much as 80%. Elsewhere, infestations have been reported to reduce water flow in canals and streams by up to 80%, this in turn may interfere with water traffic, disturb hydroelectric and urban water supplies, limit recreational water use and change the aquatic environment. Blockage of larger channels may inhibit ship movements, thus affecting trade. Submerged plants in general, have been proven to interfere with fishing operations, causing loss of revenue (Dutta and Gupta, 1973). In New Zealand a number of submerged aquatic weeds including E. canadensis cause considerable losses to hydropower stations (Howard-Williams, 1993).
Environmental ImpactTop of page
E. canadensis can from dense monospecific stands which can outcompete native plants for both space and nutrients resulting in a decrease in biodiversity and potentially local extinctions (DAISIE, 2014; NOBANIS, 2014). Changes to invertebrate communities have also been reported (RAFTS, 2009). Species of Elodea are also known to accumulate metals from the sediment and release them into the waterbody (RAFTS, 2009).
Social ImpactTop of page
E. canadensis can form large and dense stands that interfere with boating, fishing and thereby adversely affect recreation activities.
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Is a habitat generalist
- Pioneering in disturbed areas
- Tolerant of shade
- Long lived
- Fast growing
- Has high reproductive potential
- Reproduces asexually
- Damaged ecosystem services
- Ecosystem change/ habitat alteration
- Modification of hydrology
- Modification of natural benthic communities
- Modification of nutrient regime
- Modification of successional patterns
- Monoculture formation
- Negatively impacts cultural/traditional practices
- Negatively impacts livelihoods
- Negatively impacts aquaculture/fisheries
- Reduced native biodiversity
- Threat to/ loss of endangered species
- Threat to/ loss of native species
- Transportation disruption
- Competition - monopolizing resources
- Competition - shading
- Competition - smothering
- Competition - strangling
- Rapid growth
- Highly likely to be transported internationally accidentally
- Highly likely to be transported internationally deliberately
- Highly likely to be transported internationally illegally
UsesTop of page
Although E. canadensis frequently occurs as a noxious weed, in warmer climates it is important to fish as a direct food source and for shade/shelter and as food for many birds, including ducks, coots, geese, grebes, swans, marsh birds, shore birds and game birds (Sculthorpe, 1971).
Uses ListTop of page
Animal feed, fodder, forage
- Fodder/animal feed
- Wildlife habitat
- Pet/aquarium trade
Similarities to Other Species/ConditionsTop of page
Identification of E. canadensis in its vegetative form can be confused with E. nuttallii and with another member of the Hydrocharitaceae family, Hydrilla verticillata, which both have similar habits within the USA.
Distinction between E. canadensis and E. nuttallii is possible from inflorescences: E. nuttallii has sessile male flowers, which are released at anthesis and female flowers with a shorter floral tube (up to 9 cm). E. nuttallii can also occur as a common waterweed in the same geographic regions as it is rapidly expanding its distribution, but it is not yet as widespread, though is found in similar conditions and often seems to grow slightly more vigorously. The identification of both species is however sometimes confused and misidentifications occur. E. canadensis is characterised by a flat elongate leaf blade and a leaf length to width ratio of 3:1, whereas E. nuttallii has a ratio of 6:1 and typically has an obvious twist of at least half a turn along the length of the leaf blade. In some countries, the perceived occurrence of the two species of Elodea has been further confused because E. nutallii, introduced to Britain in 1939, has displaced E. canadensis in many European waterways (Barrat-Segretain et al., 2002).
Distinction between E. canadensis and H. verticillata is easy after flowering, when H. verticillata forms short branchlets on the internodes and subterranean tubers on the rootstocks (Godfrey and Wooten, 1997). Holm et al. (1997) suggest that H. verticillata may be distinguished in the vegetative stage by its conspicuously toothed leaves, while confusion with Egeria densa is avoided by the fact that the latter has leaves in whorls of four or five, not three.
Prevention and ControlTop of page
Vehicles, boats, equipment and clothing should all be checked for fragments of the plant to prevent E. canadensis from being spread into new locations (RAFT, 2009).
The drying out of lakes, ditches, ponds and irrigated fields is widely used, but is satisfactory only in countries with a prolonged dry season, or elsewhere in habitats which are easily drained (Surber, 1949; Clark, 1954; Walker, 1959). The technique has been moderately successful in the rice fields of tropical countries in eradicating E. canadensis and other submerged macrophytes. It is often supplemented by ploughing the dry soil with disks to a depth of about 25 cm. Effective removal by mechanical means is possible if the growth of the weed is in a reasonably early stage, e.g. pre-emptive control. Modifying the channel environment, however small a change and wherever possible, all helps to reduce aquatic plant growth. Demonstrated effects include reducing direct sunlight by correctly-orientated marginal shade from vegetation, or even artificial materials near the water surface or also reducing in the light penetration of water (Dawson, 1986). Environmental changes may include manipulation of water flow periodic or regular brief increases in water flow to washout out less stable vegetation or substrates, restructuring or reshaping channel shape, etc. (Dawson and Brabben, 1991; Bolton and Dawson, 1992). Restricting nutrient availability for example, the use of salt-rich water for secondary irrigation in Australia, is also likely to severely restrict the growth of freshwater plants.
Where submerged aquatic weeds cause blockage of penstock intake screens in New Zealand, the three methods commonly used for preventing such blockage are floating booms at an angle across the current to collect floating weed masses and concentrate them at a single site on the shore, mechanical screen cleaners on the intake screens, or lake draw-downs in summer to desiccate weed masses and in winter to freeze kill weed masses in shallow water (Howard-Williams, 1993).
In North America and Western Europe, special barges are used which cut the weeds and remove them from the water, alternatively, cutting machines are mounted on boats or tractors. These are used to cut the weeds in streams and small rivers letting the cut plant material float downstream (Westlake and Dawson, 1986). Mechanical mowing and rolling are widely practised in the control of weeds in irrigation ditches (Dunk and Tisdall, 1954; Seaman, 1958).
Controlling aquatic weeds with herbicides has progressed most in the USA, Western Europe, Australia and New Zealand. A datasheet on control for the UK is available (Newman, 2005). In tropical countries, the use of herbicides is far more limited. For submerged plants, a number of chemicals were used but many are now prohibited in the USA (IARC, 2014) and elsewhere. Bensulfuron methyl has given fair control of E. canadensis in Australian irrigation channels (McCorkelle et al., 1990). An overview of chemical control methods published by the US Army Corps of Engineers, Waterways Experiment Station, lists dichlobenil, diquat alone and diquat with complexed copper as 'excellent' methods; and acrolein, Endothall [endothal] demethylalkylamine salts and fluridone as 'good' methods (Westerdahl and Getsinger, 1988).
Glomski et al. (2005) established that diquat gives excellent control of E. canadensis, even at low concentrations. Diquat is often used as the herbicidal component of gels that carry the herbicide into direct contact with the weed (Barratt, 1978; Chandrasena et al., 2012).
Control by aquatic herbivores has been investigated in numerous countries (NAS, 1976). Species tested include Tilapia melanopleura, T. mossambica and the Chinese grass carp, Ctenopharyngodon idella. Since the latter is an exotic species, introduction is only allowed when the species can be confined to a particular waterbody and, therefore, investment in fences is a prerequisite. Nevertheless, several successful examples of control are known from Western Europe and the USA (Stott et al. 1971; Willey et al., 1974; Mitzner, 1978; Fowler, 1984).
ReferencesTop of page
Alaska Plant Materials Center, 2014. Waterweed - Elodea. Alaska, USA: Alaska Department of Natural Resources Division of Agriculture. http://plants.alaska.gov/invasives/elodea.htm
Alberta Biodiversity Monitoring Institute, 2014. Elodea canadensis (Canada waterweed). http://abmiapp4.srv.ualberta.ca/abmi/biodiversitybrowser/speciesprofile.jsp;jsessionid=AD7FAF57CC59EC684AA132A5FDF6AC37?tsnId=38937&rankId=220&kingdomId=3&categoryId=1&subcategoryId=12&profileId=16
Aquatic plant species in Louisiana, 2014. Noxious aquatic vegetation in Louisiana & measures to contain the plants. 10 pp. http://cpwater.kcwd.com/3lakes/aqua_veg_files/noxious_veg.pdf
Baratt PRF, 1978. Some studies on the use of alginates for the placement and controlled release of diquat on submerged aquatic plants. Pest Management Science, 9(5):425-433.
Barrat-Segretain MH; Elger A; Sagnes P; Puijalon S, 2002. Comparison of three life history traits of invasive Elodea canadensis Michx. and Elodea nuttallii (Planch.) H. St. John. Aquatic Botany, 74(4):299-313. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T4F-46RKNX8-1&_user=10&_coverDate=12%2F31%2F2002&_rdoc=3&_fmt=summary&_orig=browse&_srch=%23toc%234973%232002%23999259995%23351309!&_cdi=4973&_sort=d&_docanchor=&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=e9a0726a45d2cfe064196dfde503fdc7
Best EPH, 1977. Seasonal changes in mineral and organic components of Ceratophyllum demersum and Elodea canadensis. Aquatic Botany, 3(4):337-348
Bill S, 1969. Water weed problems of Australia. Hyacinth Control Journal, 8:1-6.
Bolton P; Dawson FH, 1992. The use of a check-list in assessing possible environmental impacts in planning watercourse improvements. In: Proceedings of the International Symposium on Effects of Watercourse Improvements: Assessment, Methodology, Management Assistance, 10-12 September 1991, Wepion, Namur, Belgium. Department for non-navigable watercourses of the Walloon Region. 29-42.
Burdick GE, 1961. Chemical control of aquatic vegetation in relation to the conservation of fish and wildlife. In: Proceedings Northeast Weed Control Conference, 15:485-492.
Chancellor AP, 1958. The Control of Aquatic Weeds and Algae. London, UK: HMSO.
Chandrasena N; Harper P; Chisholm B, 2012. Developing Hydrogel(r) for selective management of submerged aquatic weeds. Pakistan Journal of Weed Scientific Research, 18:113-123.
Clark WF, 1954. Controlling weeds and algae in farm ponds. External Bulletin Cornell Agricultural Experiment Station.
Council of Heads of Australasian Herbaria, 2014. Australia's virtual herbarium, Australia. http://avh.ala.org.au
DAISIE, 2014. Delivering Alien Invasive Species Inventories for Europe. European Invasive Alien Species Gateway. www.europe-aliens.org/default.do
Dandy JE, 1980. Elodea Michaux. In: Tutin TG, Heywood VH, Burges NA, Moore DM, Valentine DH, Walter SM, Webb DA, eds. Flora Europaea, Volume 5. Alisamtaceae to Orchidaceae Monocotyledones. Cambridge, UK: Cambridge University Press, 4-5.
Dawson FH; Brabben TE, 1991. Conflicts of interest in designing environmentally-sound channels. In: Proceedings of an African Regional Symposium on Techniques for Environmentally Sound Water Resources Development. Alexandria, Egypt, 28-30 September 1991 [ed. by Wooldridge, R.]. London, UK: Pentech Press, 135-154.
Dunk WP; Tisdall AL, 1954. Weed control in irrigation channels and drains. Technical Bulletin St. Johns Rivers Water Supply Communication.
Dutta TR; and Gupta JN, 1976. Some experiments on aquatic weed control in fisheries lakes and streams in Upper Pradesh. In: Aquatic weeds in S. E. Asia, Proceedings of a Regional Seminar on Noxious Aquatic Vegetation, New Delhi, India, 12-17 December, 1973: 249-253.
E-Flora BC, 2014. E-flora BC: Electronic Atlas of the Flora of British Columbia. British Columbia, Canada. http://ibis.geog.ubc.ca/biodiversity/eflora/
Erhard D; Gross EM, 2006. Allelopathic activity of Elodea canadensis and Elodea nuttallii against epiphytes and phytoplankton. Aquatic Botany, 85(3):203-211. http://www.sciencedirect.com/science/journal/03043770
Fowler MC, 1984. Experiments on the effects of the herbivorous fish, grass carp (Ctenopharyngodon idella Val.) on aquatic vascular plants, algae, zooplankton and phytoplankton and the importance of water temperature on the success of weed control. Technical Report, Agricultural and Food Research Council Weed Research Organization, No.77:22pp.
Glomski LAM; Skogerboe J; Getsinger KD, 2005. Comparative efficacy of diquat for control of two mwmbers of the Hydrocharitaceae: Elodea and Hydrilla. Journal of Aquatic Plant Management, 43:103-105.
Godfrey RK; Wooten JW, 1997. Aquatic and Wetland Plants of Southeastern United States. Monocotyledons. Athens, GA, USA: University of Georgia Press.
Greulich S; Trémolières M, 2006. Present distribution of the genus Elodea in the Alsatian Upper Rhine floodplain (France) with a special focus on the expansion of Elodea nuttallii St. John during recent decades. Hydrobiologia [11th International Symposium on Aquatic Weeds 'Macrophytes in Aquatic Ecosystems: From Biology to Management', Moliets et Maâ, France, 2002.], 570:249-255.
Gupta OP, 1993. Aquatic weed management. Integrated weed management for sustainable agriculture. Proceedings of an Indian Society of Weed Science International Symposium, Hisar, India, 18-20 November 1993., Vol. I:399-406.
Holm L; Doll J; Holm E; Pancho J; Herberger J, 1997. World Weeds. Natural Histories and Distribution. New York, USA: John Wiley and Sons, Inc.
Holm LG; Pancho JV; Herberger JP; Plucknett DL, 1979. A Geographical Atlas of World Weeds. New York, USA: Wiley.
Hooper FF; Cook AB, 1957. Chemical control of submerged water weeds with sodium arsenite. Pamphlet Fisheries Division Michigan Department of Conservation, 16.
Howard-Williams C, 1993. Processes of aquatic weed invasions: the New Zealand example. Journal of Aquatic Plant Management, 31:17-23.
IARC, 2014. Arsenic and arsenic compounds. International Agency for Research on Cancer Monographs. http://monographs.iarc.fr/ENG/Monographs/vol100C/mono100C-6.pdf
Invasive Species South Africa, 2014. Canadian water weed, Elodea canadensis., South Africa: Invasive Species South Africa. http://www.invasives.org.za/component/k2/item/247-canadian-water-weed-elodea-canadensis
ITIS, 2014. Integrated Taxonomic Information System. http://www.itis.gov
Kern-Hansen V; Dawson FH, 1978. The standing crop of aquatic plants of lowland streams in Denmark and the inter-relationships of nutrients in plant, sediment and water. In: Proceedings 5th EWRS International Symposium on Aquatic Weeds, Amsterdam. 143-150.
Kharchenko GV; Klochenko PD; Sosnovskaya OA, 2008. Primary production of phytoepiphyton in water bodies of Kiev. Hydrobiological Journal, 44(4):35-41. http://www.begellhouse.com/journals/38cb2223012b73f2,6d9091b16f9b2067,2c395862584b298f.html
Kozhova OM; Izhboldina LA, 1993. Spread of Elodea canadensis in Lake Baikal [in Russia]. Hydrobiologia, 259(3):203-211.
Larson D, 2003. Predicting the threats to ecosystem function and economy of alien vascular plants in freshwater environments. Literature review. Predicting the threats to ecosystem function and economy of alien vascular plants in freshwater environments. Literature review. Uppsala, Sweden: Department of Environmental Assessment, Swedish University of Agricultural Sciences.
Lia X; Manmana C; Andersonb BC, 2009. Design and performance of a water quality treatment wetland in a public park in Shanghai, China. Ecological Engineering, 35:18-24.
Mackenthun K, 1950. Aquatic weed control with sodium arsenite. Sewage Industrial Wastes, 22:1062-1067.
Mackenthun K, 1955. The control of submergent aquatic vegetation through the use of sodium arsenite. In: Proceedings Northeast Weed Control Conference, 9:545-555.
Mackenthun K, 1960. Some limnological investigations on the long term use of sodium arsenite as an aquatic herbicide. In: Proceedings Annual Northcentral Weed Control Conference, 17:30-31.
Mehta I; Krishna R; Taunk AP, 1973. The aquatic weed problem in the Chambal Irrigated Area and its control using grass carp fish. Abstracts, Regional Seminar on Noxious Aquatic Vegetation in Tropics and Sub-tropics, New Delhi, 1973., 48-49.
Murphy KJ; Barrett PRF, 1990. Chemical control of aquatic weeds. In: Pieterse AH, Murphy KV, Aquatic Weeds. Oxford, UK: Oxford Science Publication, 136-174.
National Academy of Sciences, 1976. Making Aquatic Weeds Useful: Some Perspectives for Developing Countries. Report of an ad hoc panel of the Advisory Committee on Technology Innovation. Board on Science and Technology for International Development Commission on International Relations. Part I. Using Herbivorous Animals, 13-56.
NatureServe, 2014. NatureServe Explorer Comprehensive Species Reports. Arlington, VA, USA: NatureServe. http://explorer.natureserve.org/servlet/NatureServe
NOBANIS, 2014. North European and Baltic Network on Invasive Alien Species. http://www.nobanis.org/
Ooststroom SJ van, 1973. Flora van Nederland. 17th edition. Groningen, Netherlands: Wolters-Noordhoff NV.
Oviedo Prieto R; Herrera Oliver P; Caluff MG, et al. , 2012. National list of invasive and potentially invasive plants in the Republic of Cuba - 2011. (Lista nacional de especies de plantas invasoras y potencialmente invasoras en la República de Cuba - 2011). Bissea: Boletín sobre Conservación de Plantas del Jardín Botánico Nacional de Cuba, 6(Special Issue 1):22-96.
Pip E; Simmons K, 1986. Aquatic angiosperms at unusual depths in Shoal Lake, Manitoba, Canada. Canadian Field Naturalist, 100:354-358.
Q-bank, 2014. Comprehensive databases on quarantine plant pests and diseases., The Netherlands: Q-Bank. http://www.q-bank.eu/
Revilla EP; Sastroutomo SS; Rahim MAA, 1991. Survey on aquarium plants of quarantine importance and their associated nematodes. BIOTROP Special Publication, No. 40:205-215; [a symposium on aquatic weed management held in Bogor, Indonesia, 15-17 May 1990].
Riis T; Olesen B; Clayton JS; Lambertini C; Brix H; Sorrell BK, 2012. Growth and morphology in relation to temperature and light availability during the establishment of three invasive aquatic plant species. Aquatic Botany, 102:56-64.
Sculthorpe CD, 1971. The Biology of Aquatic Vascular Plants. London, UK: Edward Arnold Publishers.
Seaman DE, 1958. Aquatic weed control. Proceedings Soil Crop Society, Florida, 18:210-215.
Sheldon R; Boylan C, 1977. Maximum depth inhabited by aquatic vascular plants. American Midland Naturalist, 97:248-254.
Simsiman GV, 1974. 1. Chemical control of aquatic weeds and its effect on the nutrient and redox status of water and sediment. 2. Persistence of diquat and endothall in the aquatic environment. Dissertation Abstracts International, B, 35(8):3717-3718; [201 pp.].
Snow JR, 1958. A preliminary report on the comparative testing of some of the newer herbicides. Proceedings Annual Conference Southeastern Association Game Fish Commission, 11:125-132.
Stott B; Cross DG; Iszard RE; Robson TO, 1971. Recent work on grass carp in the United Kingdom from the standpoint of its economics in controlling submerged aquatic plants. In: Proceedings of the European Weed Research Council. 3rd International Symposium on Aquatic Weeds, Oxford, UK, 105-116.
Surber EW, 1949. Control of aquatic plants in ponds and lakes. Fishery Leaflet Fish and Wildlife Service United States.
Thiebaut G; Rolland T; Robach F; Tremolieres M; Muller S, 1997. Some consequences of the introduction of two macrophyte species, Elodea canadensis Michaux and Elodea nuttallii St. John, in continental aquatic ecosystems: example of the Alsace plain and the northern Vosges (North-East France). (Quelques conséquences de l'introduction de deux especes de macrophytes, Elodea canadensis Michaux et Elodea nuttallii St. John, dans les écosystèmes aquatiques continentaux: exemple de la Plaine d'Alsace et des Vosges du Nord (Nord-Est de la France).) Bulletin Français de la Pêche et de la Pisciculture, No. 344/345:441-452.
Timmermans JA, 1955. Essais sur le control de la vegetation aquatique a l'aide d'herbicides. Bulletin Research Station Groenendaal, Series D, 17:38.
Turner L; Erickson W, 2003. Acrolein: analysis of risks from the aquatic herbicide use in irrigation supply canals to eleven evolutionarily significant units of Pacific Salmon and Steelhead. Report to the U. Environmental Protection Agency (EPA) Office of Pesticides (OPP). http://www.epa.gov/espp/litstatus/effects/acrolein-analysis.pdf
USDA-ARS, 2014. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx
USDA-NRCS, 2014. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/
Walker CR, 1959. Control of certain aquatic weeds in Missouri farm ponds. Weeds, 7:310-316.
Westerdahl HE; Getsinger KD, 1988. Aquatic plant identification and herbicide use guide. Volume II: Aquatic plants and susceptibility to herbicides. Aquatic Plant Control Research Program. Technical Report, A-88-89.
WHO, 1965. Snail control in the prevention of bilharziasis. Monograph Series World Health Organization.
Wild H, 1961. Harmful aquatic plants in Africa and Madagascar. Krikia, 2:1-66.
Willey RG; Doskocil MJ; Lembi CA, 1974. Potential of the white amur (Ctenopharyngodon idella Val.) as a biological control for aquatic weeds in Indiana. Proceedings of the Indiana Academy of Sciences., Volume 83:173-178.
Wychera U; Dirry P; Janauer GA, 1990. Macrophytes of the "New Danube" (Vienna) - biological and management aspects. Proceedings of the 8th international symposium on aquatic weeds, Uppsala, Sweden, 13-17 August 1990., 249-255.
OrganizationsTop of page
Netherlands: European Weed Research Society - EWRS, Postbus 29, NL-6865 ZG Doorwerth, http://www.ewrs.org
UK: Centre for Ecology and Hydrology - CEH, CEH Wallingford, Maclean Building, Crowmarsh Gifford, Walingford, Oxfordshire, http://www.ceh.ac.uk/
UK: Environment Agency, National Customer Contact Centre PO Box 544, Rotherham S60 1BY, http://www.environment-agency.gov.uk/
ContributorsTop of page
02/10/2014 Updated by:
Ian Popay, Landcare Research, New Zealand
14/01/2008 Updated by:
Hugh Dawson, CEH Wallingford, Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK
Distribution MapsTop of page
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