Limnobium laevigatum
(South American spongeplant)

Pictures

Picture	Title	Caption	Copyright
Title Habit Caption Limnobium laevigatum (West Indian spongeplant); habit, in an aquarium. July 2007. Copyright Public Domain - Released by Cardex/via wikipedia	Habit	Limnobium laevigatum (West Indian spongeplant); habit, in an aquarium. July 2007.	Public Domain - Released by Cardex/via wikipedia
Title Habit and flower Caption Limnobium laevigatum (West Indian spongeplant); habit and flower. July 2011. Copyright ©Show ryu, Japan/via wikipedia - CC BY-SA 3.0	Habit and flower	Limnobium laevigatum (West Indian spongeplant); habit and flower. July 2011.	©Show ryu, Japan/via wikipedia - CC BY-SA 3.0

Identity

Preferred Scientific Name

• Limnobium laevigatum (Humb. & Bonpl. ex Willd.) Heine

Preferred Common Name

• South American spongeplant

Other Scientific Names

• Hydrocharella echinospora Spruce ex Benth. & Hook.f.
• Hydrocharis stolonifera (G.Mey.) Kuntze
• Hydromystria laevigata (Humb. & Bonpl. ex Willd.) Hunz.
• Hydromystria sinclairii (Benth.) Hauman
• Hydromystria stolonifera G.Mey.
• Jalambicea repens Cerv.
• Limnobium bogotense (H.Karst.) Delay
• Limnobium sinclairii Benth.
• Limnobium spongia subsp. laevigatum (Humb. & Bonpl. ex Willd.) Lowden
• Limnobium stoloniferum (G.Mey.) Griseb.
• Salvinia laevigata Humb. & Bonpl. ex Willd.
• Trianea bogotensis H.Karst.
• Trianea neovisae Romero

International Common Names

• English: Amazon frogbit; smooth frogbit; South American spongeplant; West Indian spongeplant

Local Common Names

• Netherlands: Amazone kikkerbeet

Summary of Invasiveness

L. laevigatum is a floating aquatic plant native to fresh water habitats of tropical and subtropical Central and South America. It has been introduced into California as an ornamental pond plant and as an aquarium plant where it spread dramatically. There are records of this species in Australia, Indonesia, Japan, and Zambia and Zimbabwe. This species has a high reproductive potential as it can reproduce both sexually by seed and vegetatively through offshoots. It also has a high propensity for dispersal. Seeds and fragments of stolons are naturally dispersed by water and wind and can also be accidentally transported by birds and as hitchhikers on watercrafts. It is possible for L. laevigatum to form dense mats on watercourses thereby decreasing biodiversity. The impact of this species is however not fully known but the dense mats are believed to disrupt light regimes and oxygen levels in the water completely altering the habitat structure of a waterbody. Although now regulated and subject to eradication in California, L. laevigatum is still grown and sold by the aquatic nursery plant trade. This species has the potential to spread into a number of states in the USA. A weed risk assessment by USDA-APHIS (2013) for L. laevigatum rated this species as ‘high risk and a ‘major invader’.

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Monocotyledonae
•                     Order: Hydrocharitales
•                         Family: Hydrocharitaceae
•                             Genus: Limnobium
•                                 Species: Limnobium laevigatum

Notes on Taxonomy and Nomenclature

Limnobium is a group of aquatic plants in the Hydrocharitaceae, a flowering plant family found throughout the world but is primarily located in tropical regions. This family contains the genus Hydrilla, with H. verticillata known as “one of the world’s worst submersed-type aquatic weeds” (Anderson and Akers, 2011).

Limnobium was described as a genus in 1814 and contains only two species: L. laevigatum and L. spongia.L. laevigatum was described by Hermann Heine in 1968 (Heine, 1968). Depending on the treatment, the two species within the genus Limnobium are either maintained as different species or they are placed within one species but as two different varieties (L. spongia var. spongia and L. spongia var. laevigatum) (Cook and Urmi-König, 1983; Acevedo-Rodriguez and Strong, 2005).

The species name Laevigatum means smooth. Common names for this species include South American spongeplant and Amazon or smooth frogbit (Encyclopedia of Life, 2016).

Description

L. laevigatum is a floating or emergent aquatic herb. Leaves are subcircular, floating, glabrous and glossy above, with a thick layer of air-filled spongy tissue beneath, base rounded or shallowly cordate. Juvenile plants grow in rosettes of floating leaves that lie prostrate upon the water surface. A distinguishing character of the juvenile plant is the presence of spongy aerenchyma tissue upon the underside of the leaf. Mature plants grow up to 50 cm tall and have emergent leaves borne on petioles that are not swollen or inflated like the spongy leaf stalks of water hyacinth. The plant produces stolons which bear ramets which may be the main source of new plants where flowers are unknown.

Flowers are small, white, and unisexual. Female flowers have an inferior ovary. The fruit is a fleshy, berry-like capsule 4–13 mm long and 2–5 mm in diameter, borne on a recurved pedicel, developing in mud or under water. The fruit contains up to 100 seeds. The seeds are 1 mm long, ellipsoid, and hairy (Cook and Urmi-König, 1983; Encyclopedia of Life, 2016).

Distribution

L. laevigatum originates from fresh water habitats of tropical and subtropical regions in Mexico, Central and South America and the Caribbean. It is native to Mexico, Brazil, Antigua, Cuba, Dominican Republic, Guadeloupe, Martinique, Montserrat, Puerto Rico, St. Lucia, Trinidad, Costa Rica, El Salvador, Guatemala, Nicaragua, Panama, French Guiana, Guyana, Suriname, Venezuela, Argentina, Chile, Paraguay, Uruguay, Colombia, Ecuador and Peru (Bove, 2016; USDA-ARS, 2016). There are however contradictory reports on whether it’s native to Chile or not. According to the USDA-ARS (2016) it is native to Chile however Hyde et al., (2016) state that L. laevigatum is not present in Chile.

The species has been introduced to California, USA and has escaped into greater waterways including areas surrounding Redding and Arcata, the Sacramento River delta and the San Joaquin River and ponds and irrigation canals. L. laevigatum is now present in 12 counties in California (Calflora, 2016; Encyclopedia of Life, 2016).

There are some reports on occurrences outside of the Americas. The Council of Heads of Australasian Herbaria (2016) reports that populations of L. laevigatum have naturalized in the states of New South Wales and Queensland, Australia. Hyde et al., (2016) report that L. laevigatum is rare at a national level in Zimbabwe, but abundant in some dams near Harare. There is a report of this species in Zambia (Bingham et al., 2016) and Howard et al. (2016) report more localities in both Zimbabwe and Zambia. Kadono (2004) reports on a few occurrences of L. laevigatum in Japan. 

Distribution Table

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.

History of Introduction and Spread

L. laevigatum was introduced to North American waterways through use in aquariums and aquascapes (Encyclopedia of Life, 2016). It was first detected in California in 2003 in two small, isolated locations in Redding and Arcata (Anderson and Akers, 2011). After an initial quiet phase lasting about four years, it began to spread quickly (Akers, 2010). Despite active control efforts, L. laevigatum spread along several waterways in twelve counties in California, (Akers, 2010; Calflora, 2016). It has been reported in areas surrounding Redding and Arcata, the Sacramento River delta and the San Joaquin River and ponds and irrigation canals (Calflora, 2016; Encyclopedia of Life, 2016).

Introductions

Risk of Introduction

L. laevigatum is a popular aquatic plant that is readily available for sale from nurseries and via the internet. Once introduced into a new area it is likely to spread rapidly due to its high reproductive potential and high propensity for dispersal (Anderson and Akers, 2011).

L. laevigatum is listed as a state Noxious Weed (List Q) by the California Department of Food and Agriculture (CDFA) and is subject to eradication (Calflora, 2016; DiTomaso, 2010). A weed risk assessment by USDA-APHIS (2013) for L. laevigatum rated this species as ‘high risk’ and a ‘major invader’. Although L. laevigatum is now regulated and subject to eradication in California (USDA-APHIS, 2013), it’s still grown and sold by the aquatic nursery plant trade (Hrusa et al., 2002) so new introductions are likely. It has been estimated that about 29% of the USA would be suitable for L. laevigatum to establish (USDA-APHIS, 2013). This includes states in the western coast of the USA (Washington, Oregon and California) and the southern states (Texas, Arkansas, Louisiana, Mississippi, Alabama, Georgia, South and North Carolina, Florida, Hawaii and parts of Arizona and New Mexico).

The Hawkesbury River County Counsel (2014) have also declared this species to be a Noxious Weed in an area close to Sydney, Australia and therefore requires its removal.

Habitat

L. laevigatum originates from fresh water habitats of tropical and subtropical Central and South America (Encyclopedia of Life, 2016). It occurs in rivers, ponds, lakes, canals and other aquatic habitats (Cook and Urmi-König, 1983). In Puerto Rico it is reported to grow in shallow ponds, sluggish shaded rivers, fresh-water ditches and swamps at or near sea level (USDA-APHIS, 2013).

In Brazil L. laevigatum occurs in a wide range of habitats from the Amazon Rainforest, Caatinga (xerophilous thorny forest and scrub of the drylands of north-eastern Brazil), Central Brazilian Savanna, Atlantic Rainforest, Pampa (grasslands from Southern Brazil) and Pantanal (periodically flooded grasslands by the rivers Paraná and Paraguay in Central-Western Brazil) (Bove, 2016).

Habitat List

Biology and Ecology

Reproductive Biology

L. laevigatum can reproduce sexually through flower pollination and seed production (Encyclopedia of Life, 2016). The species is monoecious (there are separate male and female flowers on the same plant) (Acevedo-Rodriguez and Strong, 2005) and plants are autogamous (pollen from male flowers pollinate female flowers on the same plant). After pollination the pedicel of female flowers bends downward, forcing the fruit to develop in the water or in the mud (Cook and Urmi-König, 1983). The seeds can germinate underwater (Cook and Urmi-König, 1983). The survival time of seeds is not known. But at a pond in Redding, California seedlings of this species were appearing despite populations being almost completely suppressed for three years. This suggests that there may be a seed bank (Akers, 2010). It can also reproduce vegetatively through fragmentation of stolon segments which connect rosettes (Cook and Urmi-König, 1983).

Population Size and Structure

L. laevigatum reproduces sexually by seed and vegetatively through offshoots and as such this species can rapidly form dense floating or rooted mats on the water surface (USDA-APHIS, 2013). In one place in California 2,500 plants m^-2 were recorded (Akers, 2010).

Associations

L. laevigatum often forms sub-communities with Eichhornia azurea (Murphy et al., 2003) and often grows and floats with Eichhornia crassipes (Howard et al., 2016).

Environmental Requirements

L. laevigatum originates from fresh water habitats in the tropics and subtropics. The USDA-APHIS (2013) reports on a minimum annual precipitation of 250 mm. But as an aquatic plant, precipitation is probably not a direct limiting factor. Cold temperatures are more likely to limit its distribution. It grows in full sun, but in Puerto Rico it is also reported to grow in shady streams (Acevedo-Rodriguez and Strong, 2005; USDA-APHIS, 2013). The preferred water temperature is between 15-28°C and the preferred water’s acidity is between 6-8 pH. Although it originates from fresh water habitats, it also grows in slightly saline waters and even outcompetes other species in this environment (Perryman, 2013). In South America this species has been recorded at altitudes of more than 2,000 m (Acevedo-Rodriguez and Strong, 2005).

Climate

Water Tolerances

Means of Movement and Dispersal

Natural Dispersal

The juvenile plants of L. laevigatum have a great capacity for distribution because they are small, can float and are easily carried along by water currents (Encyclopedia of Life, 2016) and water surface winds (Howard et al., 2016). Seeds, seedlings (which develop in water) and entire plants are all dispersed by water (Lowden, 1992). There are reports of the seeds being spread by wind (Anderson and Akers, 2011).

Vector Transmission

Propagules of L. laevigatum can be dispersed by birds (Akers, 2010).

Accidental Introduction

It is possible for propagules of L. laevigatum to be dispersed as hitchhikers on watercrafts (Akers, 2010).

Intentional Introduction

L. laevigatum was intentionally introduced to North American waterways through use in aquariums and aquascapes (Encyclopedia of Life, 2016). This species is a popular plant around the world.

Impact Summary

Economic Impact

The dense mats of L. laevigatum have been reported to obstruct waterways, which reduces the quality or availability of irrigation water (DiTomaso, 2010). Observations in California confirm that vegetative mats consisting of L. laevigatum move with the current and pile up wherever there is an obstruction. The plants therefore accumulate in infrastructure for moving water and will likely jam weirs, dams, gates, and siphons, as well as being pulled into pumps where they will jam and damage the machinery. During high water, the plants may increase flood risk by piling against obstructions and clogging the channel (Akers, 2010). In South America, its native range, L. laevigatum also forms dense mats which have been reported to disrupt thousands of kilometres of drainage canals dug for transporting timber (Fernández et al., 1990). The economic cost of this species in its introduced and native range is unknown.

Environmental Impact

L. laevigatum can from dense mats across waterbodies (with up to 2,500 plants m^-2 recorded). This can dramatically change the habitat structure, limit access by other species (e.g. some aquatic birds) and block light to the aquatic community below (Akers, 2010). As a result this can decrease the biodiversity in an area (Akers, 2010). Other impacts seem likely, but have not yet been documented for this species. A pest report from California suggests that the floating mats will probably alter many ecosystem processes such as carbon and nutrient cycling. It is likely that high organic inputs into water bodies will also reduce oxygen levels in the systems (Akers, 2010).

Social Impact

Based on preliminary information from California, L. laevigatum mats are likely to affect navigation and recreational use of water bodies (Akers, 2010) just like the related L. spongia (Madsen et al., 1998). 

Risk and Impact Factors

• Invasive in its native range
• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Tolerant of shade
• Fast growing
• Has high reproductive potential
• Has propagules that can remain viable for more than one year
• Reproduces asexually

• Ecosystem change/ habitat alteration
• Monoculture formation
• Reduced native biodiversity
• Threat to/ loss of native species

• Competition - monopolizing resources
• Competition - shading
• Competition - smothering
• Rapid growth

• Highly likely to be transported internationally deliberately

Uses

Economic Value

L. laevigatum is used in aquariums and aquascapes (Encyclopedia of Life, 2016) and is grown and sold by the aquatic nursery plant trade in many parts of the world. Putzke (2009) reports on use of aquatic macrophytes such as L. laevigatum for cultivation of the mushroom, Pleurotus ostreatus in wetlands.

Environmental Services

It has been reported that L. laevigatum has a potential role in bioremediation, the use of organisms to remove or neutralise pollutants from a contaminated site (Aponte and Pacherres, 2013).

Similarities to Other Species/Conditions

With respect to its habit and morphology, L. laevigatum is very similar to Eichhornia crassipes (water hyacinth), which is widely recognised as a significant invader (Pieterse and Murphy, 1990).

L. laevigatum is also similar to the closely related species L. spongia. It can be distinguished from L. spongia by its flowers and leaf characteristics. In addition to this their distributions are different as L. spongia is not known to occur in Western States unlike L. laevigatum (Encyclopedia of Life, 2016).

Prevention and Control

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.

SPS Measures

L. laevigatum islisted as a noxious weed in California and has been classified as having high invasiveness by the California Invasive Plant Council (Cal-IPC) inventory (Cal-IPC, 2015). In New South Wales, Australia, this species is listed as a Prohibited Weed (NSW Department of Primary Industries, 2016). This means that it must be eradicated from land.

Mechanical Control

For small infestations hand removal of L. laevigatum is possible. The use of choppers and shredders however often result in the small seedlings breaking off and spreading into new areas (DiTomaso et al., 2013).

Chemical Control

A number of aquatic herbicides have been recommended for control of this species. These include diquat, glyphosate, Imazapyr and 2,4-D (DiTomaso et al., 2013; Encyclopedia of Life, 2016).

Gaps in Knowledge/Research Needs

There is currently very little information on the growth rates, nutrient requirements and cold tolerance of L. laevigatum which would help to provide information on the likelihood of this species becoming invasive in other countries. In addition to this, there have been a limited number of studies on the direct impact that this species has on the environment.

References

Acevedo-Rodríguez P; Strong MT, 2005. Monocots and Gymnosperms of Puerto Rico and the Virgin Islands. Contributions from the United States National Herbarium, volume 52:415 pp.

Akers P, 2010. Draft pest profile for Limnobium laevigatum. Unpublished report. Sacramento, California, USA: Department of Food and Agriculture.

Anderson L; Akers P, 2011. Spongeplant: A new aquatic weed threat in the Delta. Cal-IPC News, 19(1):4-5. http://www.cal-ipc.org/resources/news/pdf/Cal-IPC_News_2011Spring.pdf

Aponte H; Pacherres CO, 2013. Growth and propagation of Limnobium laevigatum (Hydrocharitaceae) under different nutrient concentrations. (Crecimiento y propagación de Limnobium laevigatum (Hydrocharitaceae) bajo diferentes concentraciones de nutrientes.) The Biologist (Lima), 11(1):69-78. http://sisbib.unmsm.edu.pe/BVRevistas/biologist/v11_n1/pdf/a6v11n1.pdf

Bingham M; Willemen A; Wursten B; Ballings P; Hyde M, 2016. Flora of Zambia. http://www.zambiaflora.com/

Bove CP, 2016. [English title not available]. (Hydrocharitaceae in Lista de Espécies da Flora do Brasil.) Jardim Botânico do Rio de Janeiro. http://floradobrasil.jbrj.gov.br/jabot/floradobrasil/FB17824

Calflora, 2016. Information on California plants for education, research, and conservation. Berkeley, California, USA: Calflora Database. http://www.calflora.org

Cal-IPC (California Invasive Plant Council), 2015. California Invasive Plants Council. www.cal-ipc.org. Berkeley, California, USA: California Invasive Plants Council.

Cook CDK; Urmi-Ko¨nig K, 1983. A revision of the genus Limnobium including Hydromystria (Hydrocharitaceae). Aquatic Botany, 17(1):1-27.

Council of Heads of Australasian Herbaria, 2016. Australia's Virtual Herbarium., Australia: Council of Heads of Australasian Herbaria. http://avh.ala.org.au

DiTomaso JM, 2010. Watch out for these red alert weeds! Cal IPC News, 17(4):4-7.

DiTomaso JM; Kyser GB; Oneto SR; Wilson RG; Orloff SB; Anderson LW; Wright SD; Roncoroni JA; Miller TL; Prather TS; Ransom C; Beck KG; Duncan C; Wilson KA; Mann JJ, 2013. Weed Control in Natural Areas in the Western United States. Davis, California, USA: Weed Research and Information Center, University of California, 544 pp.

Encyclopedia of Life, 2016. Encyclopedia of Life. http://www.eol.org

Ferna´ndez OA; Sutton DL; Lallana VH; Sabbatini MR; Irigoyen JH, 1990. Aquatic weed problems and management in South and Central America. In: Aquatic weeds: the ecology and management of nuisance aquatic vegetation [ed. by Pieterse, A. H. \Murphy, K. J.]. New York, USA: Oxford University Press, 406-425.

Hawkesbury River County Council, 2014. Media Release, New Noxious Weeds List., Australia 6 pp.

Heine HH, 1968. Hydrocharitaceae: Limnobium laevigatum. Adansonia, 8(3):315.

Howard GW; Hyde MA; Bingham; MG, 2016. Alien Limnobium laevigatum (Humb. & Bonpl. Ex Willd.) Heine (Hydrocharitaceae) becoming prevalent in Zimbabwe and Zambia. BioInvasions Records, 5(4):221-225.

Hrusa F; Ertter B; Sanders A; Leppig G; Dean E, 2002. Catalogue of non-native vascular plants occurring spontaneously in California beyond those addressed in The Jepson Manual - Part I. Madroño, 49(2):61-98.

Hyde MA; Wursten BT; Ballings P; Coates Palgrave M, 2016. Flora of Zimbabwe. http://www.zimbabweflora.co.zw

Kadono Y, 2004. Alien Aquatic Plants Naturalized in Japan: History and Present Status. Global Environmental Research, 8(2):163-169.

Lowden RM, 1992. Floral variation and taxonomy of Limnobium LC Richard (Hyrocharitaceae). Rhodora, 94(878):111-134.

Madsen JD; Owens CS; Getsinger KD, 1998. Evaluation of four herbicides for management of American frogbit (Limnobium spongia). Journal of Aquatic Plant Management, 36:148-150.

Murphy KJ; Dickinson G; Thomaz SM; Bini LM; Dick K; Greaves K; Kennedy MP; Livingstone S; McFerran H; Milne JM; Oldroyd J; Wingfield RA, 2003. Aquatic plant communities and predictors of diversity in a sub-tropical river floodplain: the upper Rio Paraná, Brazil. Aquatic Botany, 77(4):257-276.

NSW Department of Pimary Industries, 2016. Frogbit (Limnobium laevigatum). http://weeds.dpi.nsw.gov.au/Weeds/Details/286#declarations

Perryman MJ, 2013. Evaluating the invasive potential of South American spongeplant, Limnobium laevigatum (Humboldt and Bonpland ex Willdenow) Heine, in California's Sacramento-San Joaquin Delta. 20 pp. http://nature.berkeley.edu/classes/es196/projects/2013final/PerrymanM_2013.pdf

Pieterse AH; Murphy KJ, 1990. Aquatic weeds: the ecology and management of nuisance aquatic vegetation. Aquatic weeds: the ecology and management of nuisance aquatic vegetation., 593 pp.

Putzke J, 2009. Aquatic macrophytes in mushroom (Pleurotus sp.) production after waste treatment. (Macrófitas aquáticas na produção de cogumelos comestíveis (Pleurotus ostreatus sp.) após tratamento de esgoto.) Caderno de Pesquisa Serie Biologia, 21(3):81-86. http://www.bioline.org.br/abstract?id=cp09020&lang=en

SERCUL(South East Regional Centre for Urban Landcare), 2013. Amazon Frogbit, Limnobium laevigatum detected naturalized species in Western Australia. Awareness Flyer. http://www.sercul.org.au/docs/Amazon_Frogbit_lr_pdf

USDA-APHIS, 2013. Weed risk assessment for Limnobium laevigatum (Humb. & Bonpl. ex Willd.) Heine (Hydrocharitaceae) - South American spongeplant. Version 4. R. Raleigh, USA: Animal and Plant Health Inspection Service., 16 pp.

USDA-ARS, 2016. Germplasm Resources Information Network (GRIN). National Plant Germplasm System. Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

Contributors

06/02/2016 Original text by:

Ymkje van de Witte, Consultant, Wageningen, The Netherlands

Distribution Maps