Lagarosiphon major (African elodea)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Plant Type
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Biology and Ecology
- Soil Tolerances
- Natural enemies
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Impact Summary
- Economic Impact
- Environmental Impact
- Social Impact
- Risk and Impact Factors
- Uses List
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Links to Websites
- Distribution Maps
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IdentityTop of page
Preferred Scientific Name
- Lagarosiphon major (Ridley) Moss, 1928
Preferred Common Name
- African elodea
Other Scientific Names
- Elodea crispa
- Lagarosiphon muscoides Harvey, 1841
- Lagarosiphon muscoides var. major Ridley, 1886
International Common Names
- English: African curly leaved waterweed; African oxygen-weed; African waterweed; coarse oxygen weed; curly water thyme; curly waterweed; fine oxygen weed; Lagarosiphon; oxygen weed; oxygen-weed; South African oxygen weed; submerged onocotyledon
- French: elodée africaine; grand lagarosiphon
Local Common Names
- Germany: Große Wasserpest; Wassergirlande; Wechselbatt-Wasserpest
- South Africa: babergras; bobbejaantou; fynbabergras; growwe babergras; waterblommetjie
Summary of InvasivenessTop of page
L. major is an aquatic, submerged plant that can grow in dense mats up to 2-3 m thick and cause many negative environmental and economic impacts. Some of these impacts include displacing native plant species, decreasing water quality, reducing biodiversity, blocking hydroelectric intakes, impeding recreational activities, and diminishing aesthetic value. L. major is very difficult to control, and its ability to form new plants vegetatively facilitates its spread to new locations. The trade and potential escape of L. major through the aquarium and water garden industry plays a large role in its spread to new locations (Australia Natural Heritage Trust, 2003), as does the transportation of this plant on recreational equipment moving between water bodies (Cronk and Fuller, 1995). L. major is declared a noxious weed in New Zealand (Winterton and Scher, 2007), the United States (USDA-NRCS, 2006), and is on the Alert List for Environmental Weeds in Australia (Australia Natural Heritage Trust, 2003). L. major is already well established in New Zealand and parts of Europe. Other species of the family Hydrocharitaceae also have the potential to become invasive, and Elodea canadensis, Egeria densa, and Hydrilla verticillata, have been recorded as problematic outside of their native range.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Monocotyledonae
- Order: Hydrocharitales
- Family: Hydrocharitaceae
- Genus: Lagarosiphon
- Species: Lagarosiphon major
Notes on Taxonomy and NomenclatureTop of page
The genus Lagarosiphon (family Hydrocharitaceae) is generally accepted as containing approximately 15-18 species, which occur primarily in Africa, Madagascar, and India (UFL-CAIP, 2001; IPNI-GBIF, 2007). The genus name comes from the Greek lagaros meaning ‘narrow, thin’ and siphon meaning ‘tube’, probably referring to the long thin tubes that allow the female flowers to reach the water’s surface (UFL-CAIP, 2001). Lagarosiphon major was first named Lagarosiphon muscoides Harvey in 1841, was revised to L. muscoides var. major by Ridley in 1886, and further revised to its current accepted scientific name, L. major (Ridl.) Moss in 1928. L. major is synonymous with 'Elodea crispa', a name that is often used by those using the plant in aquaria (Mason, 1960). The English common name ‘oxygen weed’ refers to the species ability to “oxygenate” the water, however, the dense mats of vegetation that are characteristic of this species when introduced outside of its native range actually decrease the oxygen levels by limiting water circulation and increasing decomposition.
DescriptionTop of page
L. major is a dioecious, perennial submerged aquatic plant with adventitious roots and rhizomes that attach the plant to the substrate. The brittle, sparsely branched stem can grow up to 20 feet long, is 3-5 mm in diameter and curves like a ‘J’ towards the base. The dark green leaves are alternately spiralled around the stem, though often crowded towards the stem tip. The leaves are minutely toothed, 5-20 mm long, 2-3 mm wide and generally have tapered tips that curve down towards the stem, though in low alkalinity waters the leaves can appear straight (Australia Natural Heritage Trust, 2003). The female flower is very small, with three transparently white/pink petals that are attached to a filament-like stalk above the water’s surface. Only the female plant is known outside of its native range. The fruit is a beaked capsule, containing approximately nine seeds, each seed being approximately 1/8 inch long (UFL-CAIP, 2001).
Plant TypeTop of page Aquatic
DistributionTop of page
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.Last updated: 23 Apr 2020
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Botswana||Present||Native||ISSG (2006); EPPO (2020)|
|Lesotho||Present||Native||ISSG (2006); EPPO (2020)|
|Mauritius||Absent, Unconfirmed presence record(s)||EPPO (2020); PIER (2007)|
|-Rodrigues||Present||Introduced||Invasive||PIER (2007)||Population located on the Mascarene Islands|
|South Africa||Present||Native||ISSG (2006); EPPO (2020)|
|Zambia||Present||Native||ISSG (2006); EPPO (2020)|
|Zimbabwe||Present||Native||ISSG (2006); EPPO (2020)|
|Austria||Absent||EPPO (2020); Scher (2007)|
|France||Present, Widespread||Introduced||Invasive||ISSG (2006); EPPO (2020)|
|Germany||Present||Introduced||1966||NOBANIS (2005); EPPO (2020)|
|Ireland||Present||Introduced||1966||BioChange (2007); EPPO (2020)|
|Italy||Present||Introduced||ISSG (2006); EPPO (2020)|
|Netherlands||Present||Introduced||Thompson et al. (1995); EPPO (2020)|
|Switzerland||Present||Introduced||ISSG (2006); EPPO (2020)|
|United Kingdom||Present||Introduced||1944||CAPM-CEH (2004); EPPO (2020)|
|-Channel Islands||Present||Introduced||Australia, Natural Heritage Trust (2003)|
|Australia||Present, Only in captivity/cultivation||Introduced||Invasive||Australia, Natural Heritage Trust (2003); EPPO (2020)|
|-New South Wales||Absent, Eradicated||Australia, Natural Heritage Trust (2003)||Small population near Newcastle eradicated in the late 1970s|
|-Queensland||Present, Only in captivity/cultivation||Introduced||1990||Australia, Natural Heritage Trust (2003)||Cultivated population|
|-Victoria||Absent, Eradicated||Australia, Natural Heritage Trust (2003)||Small population near Melbourne eradicated in the late 1970s|
|New Zealand||Present||Introduced||1950||Invasive||ISSG (2006); EPPO (2020)|
History of Introduction and SpreadTop of page
L. major was first reported as being naturalized in New Zealand in 1950, and by 1957 the population had grown to nuisance levels in Lake Rotorua. It is believed that L. major was intentionally introduced to Lake Rotorua with the intention of improving the oxygen levels (Cronk and Fuller, 1995), although the dense mats of vegetation that occurred actually decreased the lake oxygen levels. L. major spread to Lake Taupo around 1966, and was probably introduced to the lake by recreational boat traffic (Cronk and Fuller, 1995). L. major continues to spread to many other freshwater lakes in New Zealand, and is a major concern in the region.
L. major was first recorded in a chalk pit in Britain in 1944, and has since spread to several other locations throughout Europe. L. major was first recorded both in Germany and Ireland in 1966, and its introductions were intentional horticultural and ornamental releases (NOBANIS, 2005; BioChange, 2007). In Ireland, the occurrence of L. major between 1987-1999 was recorded as being present in 7 hectads (1 hectad = 10km X 10km)(BioChange, 2007), though many additional L. major occurrences have been reported during the last five years (NBGI, 2007).
IntroductionsTop of page
|Introduced to||Introduced from||Year||Reason||Introduced by||Established in wild through||References||Notes|
|Natural reproduction||Continuous restocking|
|Germany||Africa||1966||Horticulture (pathway cause)||NOBANIS (2005)|
|Ireland||Southern Africa||1966||Ornamental purposes (pathway cause)||Yes||BioChange (2007)|
|New Zealand||Africa||1950||Ornamental purposes (pathway cause)||Yes||NZPCN (2005)|
Risk of IntroductionTop of page
L. major is a popular aquarium and water garden plant, and the ability to order this plant over the internet and through mail order gives it the ability to travel to all parts of the world (Australia Natural Heritage Trust, 2003). It has escaped confinement and has been intentionally introduced on several occasions outside of its native range. In the locales to which it has been introduced, it has often become the dominant plant species, outcompeting both native and previously established exotic species, in addition to displacing other species which depend on the ecosystem. L. major has the potential to colonize large areas within a growing season by means of vegetative propagation, and is listed as a noxious weed in many parts of the world.
HabitatTop of page
L. major prefers lakes, reservoirs, and slow moving rivers with silty or sandy bottoms. L. major is also known to occur in wetlands, water courses, riparian zones (ISSG, 2006), canals and drainage ditches (CAPM-CEH, 2004). It prefers the cool waters of the temperate zone, and grows best under high light intensity. L. major can grow to depths of 6.6 m (Coffey and Wah, 1988), but may grow to only 1 m in murky water (Australia Natural Heritage Trust, 2003). L. major grows best in areas sheltered from wind, waves, and current.
Habitat ListTop of page
|Terrestrial ‑ Natural / Semi-natural||Wetlands||Present, no further details||Harmful (pest or invasive)|
|Secondary/tolerated habitat||Harmful (pest or invasive)|
|Lakes||Principal habitat||Harmful (pest or invasive)|
|Reservoirs||Secondary/tolerated habitat||Harmful (pest or invasive)|
|Rivers / streams||Principal habitat||Harmful (pest or invasive)|
|Ponds||Principal habitat||Harmful (pest or invasive)|
Biology and EcologyTop of page
L. major can live in a range of nutrient levels, however, in lakes with accelerated eutrophication and severely decreased water clarity, L. major abundance declines. L. major prefers high light intensity, and its best growth is recorded at 600 micro-einsteins/m2/h (Schwarz and Howard-Williams, 1993). L. major is able to withstand a relatively high pH, and its own photosynthetic activity has been recorded as raising pH levels to 10-10.4 in the surrounding water (CAPM-CEH, 2004). In conjunction with pH, L. major can survive in high alkalinity conditions as well. The optimum temperature of L. major is 20-23°C, with a maximum temperature of approximately 25°C. L. major is thought to be absent below temperatures of 10°C (Australia Natural Heritage Trust, 2003).
ClimateTop of page
|B - Dry (arid and semi-arid)||Tolerated||< 860mm precipitation annually|
|BS - Steppe climate||Tolerated||> 430mm and < 860mm annual precipitation|
|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||Tolerated||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)|
Soil TolerancesTop of page
- very alkaline
Natural enemiesTop of page
Notes on Natural EnemiesTop of page
McGregor and Gourlay (2002) report the nematode Aphelenchoides fragariae attacking the apical tips of L. major. Nymphula nitens has also been reported as feeding on several aquatic weeds, though it is not specific to L. major.
Means of Movement and DispersalTop of page
Natural Dispersal (Non-Biotic)
Pathway CausesTop of page
|Aquaculture||Yes||Cronk and Fuller, 1995|
|Escape from confinement or garden escape||Yes||Australia Natural Heritage Trust, 2003|
|Flooding and other natural disasters||Yes||Australia Natural Heritage Trust, 2003|
|Intentional release||Yes||Yes||Cronk and Fuller, 1995|
|Interconnected waterways||Yes||ISSG, 2006|
|Internet sales||Yes||Australia Natural Heritage Trust, 2003|
|Ornamental purposes||Yes||Yes||USDA-ARS, 1997|
Pathway VectorsTop of page
|Aircraft||seaplanes, float planes||Yes||McGregor and Gourlay, 2002|
|Floating vegetation and debris||Yes||Cronk and Fuller, 1995|
|Land vehicles||Vegetation moving between water bodies on vehicles, moving boats, trailers, recreational equipment||Yes||Yes||Cronk and Fuller, 1995|
|Mail order||Yes||Australia Natural Heritage Trust, 2003|
|Pets and aquarium species||Yes||Australia Natural Heritage Trust, 2003|
|Ship structures above the water line||Vegetation moving between water bodies on boats, trailers, recreational equipment, etc.||Yes||Cronk and Fuller, 1995|
|Water||Yes||Cronk and Fuller, 1995|
Impact SummaryTop of page
Economic ImpactTop of page
L. major has blocked intakes of hydroelectric systems and has the potential to limit flow in irrigations channels. In addition, the loss of recreational and aesthetic value associated with L. major can also cause a decline in lakefront property values, as well as possible declines in tourism-related revenue for the community.
Environmental ImpactTop of page
Social ImpactTop of page
L. major can form dense mats that impede recreational activities such as boating, fishing, swimming, water skiing, canoeing, and kayaking. In addition, unsightly mats of vegetation decrease aesthetic values. These declines in recreational and aesthetic values can decrease tourism, which can be a major source of income within the community.
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Highly mobile locally
- Fast growing
- Has high reproductive potential
- Has propagules that can remain viable for more than one year
- Reproduces asexually
- Damaged ecosystem services
- Ecosystem change/ habitat alteration
- Modification of hydrology
- Modification of natural benthic communities
- Modification of nutrient regime
- Monoculture formation
- Negatively impacts cultural/traditional practices
- Negatively impacts livelihoods
- Negatively impacts aquaculture/fisheries
- Negatively impacts tourism
- Reduced amenity values
- Reduced native biodiversity
- Threat to/ loss of native species
- Transportation disruption
- Competition - monopolizing resources
- Competition - shading
- Interaction with other invasive species
- Rapid growth
- Highly likely to be transported internationally deliberately
- Difficult to identify/detect as a commodity contaminant
- Difficult to identify/detect in the field
- Difficult/costly to control
UsesTop of page
Ornamental plants of L. major, often sold under the name 'Elodea crispa', are sold for aquariums and ponds, though the specific economic value of this particular species in the ornamental plant trade is unknown. L. major was also once sold as capable of 'water purification', though the continuance of this practice is unknown (NBGI, 2007).
The utilization of L. major as fodder for stock food was explored as a possible usage of harvested biomass, though the high levels of arsenic accumulated by the plants proved unsuitable (ISSG, 2006).
L. major is enjoyed by many aquarium hobbyists due to the minimal maintenance required and ease of growth.
In severely disturbed ecosystems where exotics are the only plants capable of surviving, removal of plants such as L. major can further degrade the habitat. L. major can provide some habitat for aquatic fauna, its leaf surface supports periphyton, and plant stands can increase sedimentation, which could be beneficial in some areas (McGregor and Gourlay, 2002).
Uses ListTop of page
Animal feed, fodder, forage
- Fodder/animal feed
- Botanical garden/zoo
- Pet/aquarium trade
Detection and InspectionTop of page
Similarities to Other Species/ConditionsTop of page
Several other species in the family Hydrocharitaceae look very similar to L. major, including Egeria densa, Elodea canadensis, and Hydrilla verticillata. However, unlike the leaves of the other species, which grow in groups or whorls circularly around the stem, the leaves of L. major are distinguishably alternately spiralled (Australia Natural Heritage Trust, 2003). The presence of recurved leaves and a downward curving stem towards the apex also help to distinguish L. major from these similar species (Scher, 2007). L. major is often also mislabelled as 'Elodea crispa', usually by those dealing with the plant in the aquarium trade.
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
Cultural control and sanitary measures
Several regions where aquatic invasives have established now require that recreationists drain all water and clean off all gear (boats, trailers, fishing equipment, etc.) used on water bodies in order to minimize the chance of spreading aquatic invasive species, such as L. major, to other areas.
Attempts to control L. major has had limited efficacy due to its ability to propagate vegetatively through fragments and underwater roots and rhizomes. Attempts to mechanically harvest only serve as means of creating and introducing more plant fragments, and potentially aiding in dispersal to new locations. There has been some success with mechanical harvesting that is conducted at or near root level (Caffrey and Acevedo, 2007). Suction dredging has also been used, but it is nearly impossible to remove all vegetation and regeneration is highly likely (Australia Natural Heritage Trust, 2003).
Weed mats have been used in small localized areas (ENVBOP, 2003; Caffrey and Acevedo, 2007), but are difficult to maintain. It may also be possible to alter water depth and flow speeds in channels, thereby rendering them uninhabitable, though there are limited practical situations where these control methods can be applied (CAPM-CEH, 2004).
Several countries have banned the importation or sale of exotic plants, such as L. major, in attempts to minimize the chance of introduction to non-native regions.
McGregor and Gourlay (2002) report that the nematode Aphelenchoides fragariae has been recorded attacking the apical tips of L. major, resulting in shoot dwarfing. In addition, Nymphula nitens also feeds on many aquatic weeds and might be a potential biocontrol agent, but it will also consume native vegetation. Neither species has yet been studied for its potential as a biological control agent.
Grass carp have been suggested as a potential biological control method, though studies have shown that L. major is not one of their preferred food sources, and their introduction would negatively impact the remaining native submerged vegetation (CAPM-CEH, 2004).
L. major has been found to be susceptible to herbicides containing terbutryn or dichlobenil. The preferred method of control is an early spring (March or early April in the Northern hemisphere) application of dichlobenil. Terbutryn (Clarosan) should only be used when L. major is the overwhelmingly dominant species, because this herbicide will kill most species of submerged aquatic plants, and has the ability to cause fish kills due to a sudden decline in photosynthesis (CAPM-CEH, 2004). Diquat has also been moderately successful against L. major, though its effectiveness differs greatly among scenarios, and it is not effective in turbid waters (UFL-CAIP, 2001).
ReferencesTop of page
Australia Natural Heritage Trust, 2003. Lagarosiphon - Lagarosiphon major. Weed Management Guide. Australia: Natural Heritage Trust. http://www.weeds.gov.au/publications/guidelines/alert/pubs/l-major.pdf
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
James CS; Eaton JW; Hardwick K, 1999. Competition between three submerged macrophytes, Elodea canadensis Michx, Elodea nuttallii (Planch.) St John and Lagarosiphon major (Ridl.) Moss. In: Hydrobiologia [ed. by Caffrey JM, Barrett PRF, Ferreira MT, Moreira IS, Murphy KJ, Wade PM], 35-40.
Rattray MR; Howard-Williams C; Brown JM, 1994. Rates of early growth of propagules of Lagarosiphon major and Myriophyllum triphyllum in lakes of differing trophic status. New Zealand Journal of Marine and Freshwater Research, 28(3):235-241.
USDA-ARS, 1997. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx
Winterton S; Scher J, 2007. Aquarium and Pond Plants of the World, Edition 2.0, Lucid v. 3.4. USA: USDA/APHIS/PPQ Center for Plant Health Science and Technology, North Carolina State University, and California Department of Food and Agriculture. http://www.lucidcentral.org/keys/aquariumplants2/
Australia, Natural Heritage Trust, 2003. Lagarosiphon - Lagarosiphon major. In: Weed Management Guide, Australia: Natural Heritage Trust. http://www.weeds.gov.au/publications/guidelines/alert/pubs/l-major.pdf
CABI, Undated. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
ContributorsTop of page
08/04/08 Original text by:
Alison Mikulyuk, Wisconsin Dept of Natural Resources, Science Operations Center, 2801 Progress Rd, Madison, WI 53716, USA
Michelle Nault, Wisconsin Department of Natural Resources, 2801 Progress Rd, Madison, WI 53716-3339, USA
Distribution MapsTop of page
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