Azolla pinnata (mosquito fern)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Plant Type
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Hosts/Species Affected
- Biology and Ecology
- Air Temperature
- Rainfall Regime
- Natural enemies
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Plant Trade
- Impact Summary
- Environmental Impact
- Impact: Biodiversity
- 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
- Azolla pinnata R. Br.
Preferred Common Name
- mosquito fern
International Common Names
- English: African azolla; feathered mosquito fern; ferny azolla; pinnate mosquito fern; water velvet
Local Common Names
- Australia: red azolla; red water fern; water moss
- Germany: Afrikanischer Algenfarn; Gefiederter Algenfarn
- Japan: aka-ukikusa
- Vietnam: beo-dau
- AZOPI (Azolla pinnata)
Summary of InvasivenessTop of page
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Pteridophyta
- Class: Filicopsida
- Family: Azollaceae
- Genus: Azolla
- Species: Azolla pinnata
Notes on Taxonomy and NomenclatureTop of page
DescriptionTop of page
Plant TypeTop of page
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: 25 Feb 2021
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Central African Republic||Present, Localized||Native|
|Congo, Democratic Republic of the||Present, Localized||Native|
|Congo, Republic of the||Present, Localized||Native|
|Côte d'Ivoire||Present, Localized||Native|
|Sierra Leone||Present, Localized||Native|
|South Africa||Present, Localized||Native|
|-Assam||Present, Widespread||Native||Original citation: Devashish and Kar Barbhuiya (2001)|
|-Bihar||Present, Widespread||Native||Original citation: Srivastava and Amarjeet Singh (1984)|
|-Jammu and Kashmir||Present, Widespread||Native|
|North Korea||Present, Localized|
|Sri Lanka||Present, Localized||Native|
|-New South Wales||Present||Native|
|-Northern Territory||Present, Localized||Native|
|New Zealand||Present, Localized||Introduced||Invasive|
|Papua New Guinea||Present, Localized||Native|
History of Introduction and SpreadTop of page
Risk of IntroductionTop of page
HabitatTop of page
Habitat ListTop of page
|Terrestrial||Natural / Semi-natural||Riverbanks||Present, no further details|
|Terrestrial||Natural / Semi-natural||Wetlands||Present, no further details|
|Freshwater||Present, no further details||Harmful (pest or invasive)|
Hosts/Species AffectedTop of page
Biology and EcologyTop of page
Known chromosome counts for the genus Azolla are centred around n=22, with many variations. This probably indicates that a tetraploid n=22 was the original count, deriving from n=11. A. pinnata has been reported as n=22 (tropical Africa), n=33 (Asia) and n=44 (Australia) (Knouse, 1997).
Physiology and Phenology
Growth occurs all year round in tropical and sub-tropical areas. Reproduction by spores is often triggered by crowding, as is a change to red coloration, although there is no definitive link between sporulation and colour change. Fronds divide vegetatively, with doubling possible every 3 days, leading to very rapid growth rates and colonization of new lakes and ponds. Development of the red coloration of A. pinnata is also promoted by phosphorus starvation (Nirmala Gunapala and Amarasiri, 1983).
The upper surfaces of the leaves are totally water repellent and, if completely submerged, the plants quickly refloat with the right side up (Croft, 1986). Deoxyanthocyanins are present in A. pinnata and act as a feeding deterrent to molluscs (Cohen et al., 2002a).
Vegetative reproduction is by fragmentation of the fronds. Sexual reproduction leads to the formation of spores that are released into the water. Azolla is heterosporous, a clear adaptation to an aquatic environment. Sporangia are borne in sporocarps, usually paired micro- and megasporocarps, borne in the axils of the submerged lobes, basally on the branches, quite enclosed by a thin indusium. The microsporocarp is large, globose, containing several to many globose microsporangia, each containing 32-64 microspores. The megasporocarp is smaller, containing a single megasporangium with a single megaspore. Spores are globose, trilete, smooth to variously pitted or sculptured. Microspores are imbedded in the outer edge of several mucilaginous masses (massulae) in the microsporangium, the massulae bearing several to many, hooked (glochidiate) or non-hooked, septate or non-septate processes on one or all sides. Megaspores have three or nine apical massulae or 'floats'.
Nitrogen levels are relatively unimportant for growth of Azolla, although growth rates are higher in eutrophic conditions. In southeast Asian countries, it is especially common in (wet) rice fields. It is used as a natural fertilizer, which takes advantage of the nitrogen-fixing abilities of the symbiotic blue-green algae (Moore 1969; Lumpkin and Plucknett, 1980).
A feature of the genus is the symbiotic association of the cyanobacterium Anabaena azollae. This alga lives endophytically in the inter-cellular spaces of basal leaves of Azolla. Atmospheric nitrogen is fixed by heterocysts in the algal cell, and transferred as ammonia to Azolla.
Air TemperatureTop of page
|Parameter||Lower limit||Upper limit|
|Absolute minimum temperature (ºC)||4|
|Mean annual temperature (ºC)||14||23|
|Mean maximum temperature of hottest month (ºC)||14||35|
|Mean minimum temperature of coldest month (ºC)||12||29|
Rainfall RegimeTop of page
Natural enemiesTop of page
Notes on Natural EnemiesTop of page
Dath and Singh (1998) reported that A. pinnata was very susceptible to the fungus Rhizoctonia solani [Thanatephorus cucumeris], and Shahjahan et al. (1980) reported inhibition of growth of A. pinnata by Sclerotium rolfsii [Corticium rolfsii] and Rhizoctonia sp. These fungal pathogens are opportunists and also a attack a range of crop plants. Fannah (1987) reported a completed life cycle of Elophila africalis on A. pinnata in Sierra Leone which was followed up by Roberts et al. (1998). Sands and Kassulke (1986) reported oviposition by females of Paulinia acuminata after feeding on A. pinnata. However, P. acuminata was introduced into Africa, India and Fiji for the control of Salvinia molesta but is not host specific and did not contribute significantly to control (Julien and Griffiths, 1998). Therefore, it is unlikely that it is an important constraint on A. pinnata.
The frond-feeding weevil Stenopelmus rufinasus was imported into quarantine for testing as a potential natural enemy for the A. filiculoides in South Africa (Hill, 1998). Both the adults and larvae severely reduced A. filiculoides in the laboratory. Of 31 plant species in 19 families tested, adult feeding, oviposition and larval development were only recorded on the Azolla species (A. filiculoides, A. pinnata subsp. poss. asiatica, A. pinnata subsp. africana and A. nilotica). A. filiculoides was the most suitable host for the weevil. Low adult emergence from A. nilotica and A. pinnata subsp. africana would probably prevent the weevil from establishing on them in the field. A. pinnata subsp. poss. asiatica supported greater development.
Means of Movement and DispersalTop of page
Vegetative fragments and spores can spread easily downstream, and be carried with floodwaters to colonize new areas.
It is sometimes introduced and used by farmers as a natural fertilizer for its ability to fix atmospheric nitrogen in rice paddies. It is thought to have been spread in New Guinea with cattle between drinking ponds (Croft, 1986).
It has been introduced as an ornamental pond and aquarium plant.
Plant TradeTop of page
|Plant parts not known to carry the pest in trade/transport|
|Fruits (inc. pods)|
|Growing medium accompanying plants|
|Stems (above ground)/Shoots/Trunks/Branches|
|True seeds (inc. grain)|
Impact SummaryTop of page
|Fisheries / aquaculture||Negative|
ImpactTop of page
Environmental ImpactTop of page
Impact: BiodiversityTop of page
Risk and Impact FactorsTop of page
- Invasive in its native range
- Proved invasive outside its native range
- Highly adaptable to different environments
- Highly mobile locally
- Has high reproductive potential
- Has propagules that can remain viable for more than one year
- Damaged ecosystem services
- Ecosystem change/ habitat alteration
- Negatively impacts agriculture
- Negatively impacts tourism
- Reduced amenity values
- Reduced native biodiversity
- Competition - monopolizing resources
- Highly likely to be transported internationally accidentally
- Highly likely to be transported internationally deliberately
UsesTop of page
Satapathy and Singh (1985) reported suppression of weed quantity by up to 50% in rice crops when A. pinnata was present, in agreement with the results of Kannaiyan et al. (1983) and Janiya and Moody (1984).
It is used as an ornamental pond and aquarium plant.
Broiler chicken diets have been supplemented with up to 5% A. pinnata resulting in improved live weight, production number, protein efficiency and feed conversion ratios (Basak et al., 2002). A. pinnata was assessed as a promising additive to abalone feed by Reyes and Fermin (2003). Dried, powdered A. pinnata has also been used to supplement carp diets (Basudha and Vishwanath, 1997).
A. pinnata has been investigated for use in the decontamination of land in India (Kaur, 2001). Bacterial flocs produced on decaying A. pinnata enhanced degradation of diesel in experimental microcosms by up to 100% (Cohen et al., 2002b).
There is some evidence to suggest that extracts of A. pinnata have inhibitory effects on root-knot nematodes (Thakar et al., 1988; Patel et al., 1994, Malek et al., 1996; Ramakrishnan et al. 1996; Hossain et al. 2002,), on Cucumber green mottle mosaic virus (Tewari et al., 2001) and on the mollusc Biomphalaria alexandrina (Abdel-Hafez, 1997; Zidan et al., 1998).
Uses ListTop of page
Animal feed, fodder, forage
- Fodder/animal feed
Similarities to Other Species/ConditionsTop of page
A. mexicana (northern South America to western North America); A. microphylla (tropical and subtropical Americas); A. rubra (Australia and New Zealand); A. nilotica (tropical Africa).
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.Chemical Control
A. pinnata is susceptible to applications of diquat, glyphosate and terbutryn. A mixture of kerosene and a wetting agent is used for control of A. pinnata in Australia (Wall, 1994).
ReferencesTop of page
Abdel-Hafez AM; Zidan ZH; Abdel-Megeed MI; El-Emam MA; Ragab FM; El-Deeb FA, 1997. Effect of the plant Azolla pinnata on survival, growth rate, fecundity and hatchability of egg-masses of Biomphalaria alexandrina snails. Journal of the Egyptian Society of Parasitology, 27(3):825-841.
Basak B; Pramanik AH; Rahman MS, 2002. Azolla (Azolla pinnata) as a feed ingredient in broiler ration. International Journal of Poultry Science 1:29-34.
Basudha C; Vishwanath W, 1997. Formulated feed based on aquatic weed Azolla and fish meal for rearing medium carp Osteobrama belangeri (Valenciennes). Journal of Aquaculture in the Tropics, 12(3):155-164; 21 ref.
Bravo MVA, 1991. Aquatic weeds in the Philippines: a general assessment of scenario. BIOTROP Special Publication, No. 40:47-49; [A symposium on aquatic weed management held in Bogor, Indonesia, 15-17 May 1990].
Chapman AL; Shaw W; Renaud S, 1981. Effect of temperature on the growth and acetylene reduction activity of Azolla pinnata from the Darwin region of northern Australia. Journal of the Australian Institute of Agricultural Science, 47(4):223-225.
Cohen MF; Williams J; Yamasaki H, 2002. Biodegradation of diesel fuel by an Azolla-derived bacterial consortium. Journal of Environmental Science and Health. Part A, Toxic/Hazardous Substances & Environmental Engineering, 37(9):1593-1606.
Croft JR, 1985. Ferns and Fern Allies. In: Leach GJ, Osborne PL, eds. Freshwater Plants of Papua New Guinea. University of Papua New Guinea, 33-74.
Croft JR, 1986. The aquatic Pteridophytes of New Guinea. Australian National Herbarium, Centre for Plant Biodiversity Research. http://www.anbg.gov.au/projects/fern/aquatic/.
Dyer RA; Codd LE; Rycroft HB, 1963. Flora of Southern Africa-Volume 26. Myrsinaceae, Primulaceae, Plumbaginaceae, Sapotaceae, Ebenaceae, Oleaceae, Salvadoraceae, Loganiaceae, Gentianaceae, and Apocynaceae. 1963. pp. vii + 307. Many refs. Price Rands 4.60. Government Printer, Pretoria.
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Exell AW; Wild H, 1960. Flora Zambesiaca, Vol. 1. London, UK: Crown Agents for Oversea Governments and Administrations.
Gopal GV, 2000. Azolla pinnata r.br. Pteridophyte; Salviniales (Azollaceae) in the management of lake agro ecosystem. In: Ramachandra TV, Rajasekara Murthy C, Nhalya, N, eds. Proceedings of Lake 2000. International Symposium on Restoration of Lakes and Wetlands, 27th to 29th November 2000, Indian Institute of Science, Bangalore. India.
Hall JW, 1969. Studies on fossil Azolla. American Journal of Botany, 56:1173-1180.
Hossain M; Ahmad MU; Ahmed N; Hossain MA; Alim MA, 2002. A study on control of root knot nematode (Meloidogyne javanica) of wheat. Indian Agriculturist, 46:121-128.
Johns RJ, 1991. Pteridophytes of Tropical East Africa. Kew, UK: Royal Botanic Gardens.
Kaur H, 2001. Biomass production of Azolla pinnata R. BR. in contaminated soils of Punjab (India). 5th International Biomass Conference of the Americas, Florida 2001.
Knouse JA, 1997. Genus Azolla: the mosquito ferns. http://www.jaknouse.athens.oh.us/ferns/g_azol.html#top.
Konar RN; Kapoor RK, 1974. Anatomical studies on Azolla pinnata. Phytomorphology, 22:211-223.
Konar RN; Kapoor RK, 1975. Embryology of Azolla pinnata. Phytomorphology, 24:228-261.
Loyal DS, 1974. Chromosome size and structure in some heterosporous ferns with a bearing on evolutionary problems. In: Kachroo P, ed. Advancing Frontiers in Cytogenetics, 293-298.
Loyal DS; Gollen AK; Ratra R, 1982. Morphological and cytotaxonomic observations on Azolla pinnata. Fern Gazette, 12:230-232.
Mansor M; Sam SK, 1992. The competition between three species of small-leaf floating plants which are frequently found in rice growing areas of northern Peninsula Malaysia. Proceedings of the 3rd international conference on plant protection in the tropics, Genting Highlands, Malaysia, 20-23 March 1990., Vol. 6:242-246.
Moore AW, 1969. Azolla: biology and agronomic significance. Botanical Review, 35:17-35.
Owen SJ, 1997. Ecological weeds on conservation land in New Zealand: a database. Wellington, New Zealand: Department of Conservation.
Patel HR; Patel DJ; Patel CC; Thakar NA, 1994. Effectivity of Clerodendron inerme L., Catharanthus roseus (L.) G. Don. and Azolla pinnata R. Br. for management of root-knot nematodes in okra. Pakistan Journal of Nematology, 12(1):95-98; 9 ref.
Ramakrishnan S; Gunasekaran CR; Vadivelu S, 1996. Effect of bio-fertilizers Azolla and Azospirillum on root-knot nematode, Meloidogyne incognita and plant growth of okra. Indian Journal of Nematology, 26(2):127-130; 9 ref.
Reed CF, 1965. Distribution of Salvinia and Azolla in South America and Africa in connection with studies for control by insects. Phytologia, 12:121-130.
Satapathy KB; Chand PK, 1984. Studies on the ecology of Azolla pinnata R. Br. of Orissa. Journal of the Indian Botanical Society, 63:44-52.
Sevichan PJ; Madhusoodanan PV, 1995. Comparative performance of three species of Azolla as a biofertilizer with different levels of chemical nitrogen fertilizer in the paddy fields. Journal of Economic and Taxonomic Botany, 19(3):683-686.
Thakar NA; Patel CC; Patel HR, 1988. Effect of extracts of Azolla pinnata on egg hatching of root knot nematodes Meloidogyne incognita and M. javanica. Madras Agricultural Journal, 75(7-8):297-299; 6 ref.
Thomas KJ, 1976. Observations on the aquatic vegetation of Trivandrum, Kerala. Aquatic weeds in S. E. Asia. Proceedings of a Regional Seminar on Noxious Aquatic Vegetation, New Delhi 1973. W. Junk. The Hague Netherlands, 99-102
Thuoc NH; Tinh NH; Nhu DX; Thong NW; Thach HN, 1978. Anh huo’ng cua anh sang va nhiet do den sinh truong va quang hop cua beo dau. (Vliyanie sveta i temperatury na rost i fotosintez Azolla pinnata.) Khoa Hoc va Kythuat Nong Nghiep, 2:91-95.
USDA-ARS, 2005. 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, 2004. The PLANTS Database, Version 3.5. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov.
Wall H, 1994. Water Facts - Control of Azolla (Red Water Fern). Queensland, Australia: Rural Water Advisory Services, Department of Natural Resources.
Waterhouse DF, 1993. The Major Arthropod Pests and Weeds of Agriculture in Southeast Asia. ACIAR Monograph No. 21. Canberra, Australia: Australian Centre for International Agricultural Research, 141 pp.
Zidan ZH; Abdel-Hafez AM; Abdel-Megeed MI; El-Emam MA; Ragab FM; El-Deeb FA, 1998. Susceptibility of Biomphalaria alexandrina to the plant Azolla pinnata and some herbicides in relation to infection with Schistosoma mansoni miracidia. Journal of the Egyptian Society of Parasitology, 28(1):89-100.
Anon, 1963. Flora of Southern Africa-Volume 26. Myrsinaceae, Primulaceae, Plumbaginaceae, Sapotaceae, Ebenaceae, Oleaceae, Salvadoraceae, Loganiaceae, Gentianaceae, and Apocynaceae. [ed. by Dyer R A, Codd L E, Rycroft H B]. Pretoria, South Africa: Government Printer. vii + 307 pp.
CABI, Undated. Compendium record. Wallingford, UK: CABI
CABI, Undated a. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
Chapman A L, Shaw W, Renaud S, 1981. Effect of temperature on the growth and acetylene reduction activity of Azolla pinnata from the Darwin region of northern Australia. Journal of the Australian Institute of Agricultural Science. 47 (4), 223-225.
Croft JR, 1985. Ferns and Fern Allies. In: Freshwater Plants of Papua New Guinea, [ed. by Leach GJ, Osborne PL]. University of Papua New Guinea. 33-74.
Croft JR, 1986. The aquatic Pteridophytes of New Guinea. In: Australian National Herbarium, Centre for Plant Biodiversity Research, http://www.anbg.gov.au/projects/fern/aquatic/
Exell AW, Wild H, 1960. Flora Zambesiaca., 1 London, UK: Crown Agents for Oversea Governments and Administrations.
Johns RJ, 1991. Pteridophytes of Tropical East Africa., Kew, UK: Royal Botanic Gardens.
Kiran G G R, Rao A S, 2013. Survey of weed flora in transplanted rice in Krishna agroclimatic zone of Andhra Pradesh, India. Pakistan Journal of Weed Science Research. 19 (1), 45-51. http://www.wssp.org.pk/4-19-1-45-51.pdf
Mansor M, Sam S K, 1992. The competition between three species of small-leaf floating plants which are frequently found in rice growing areas of northern Peninsula Malaysia. In: Proceedings of the 3rd international conference on plant protection in the tropics, Genting Highlands, Malaysia, 20-23 March 1990. [Proceedings of the 3rd international conference on plant protection in the tropics, Genting Highlands, Malaysia, 20-23 March 1990.], [ed. by Ooi PAC, Lim GS, Teng PS]. Kuala Lumpur, Malaysia: Malaysian Plant Protection Society. 242-246.
Owen SJ, 1997. Ecological weeds on conservation land in New Zealand: a database., Wellington, New Zealand: Department of Conservation.
Satapathy KB, Chand PK, 1984. Studies on the ecology of Azolla pinnata R. Br. of Orissa. In: Journal of the Indian Botanical Society, 63 44-52.
Thomas K J, 1976. Observations on the aquatic vegetation of Trivandrum, Kerala. In: Aquatic weeds in S. E. Asia. Proceedings of a Regional Seminar on Noxious Aquatic Vegetation, New Delhi 1973. [Aquatic weeds in S. E. Asia. Proceedings of a Regional Seminar on Noxious Aquatic Vegetation, New Delhi 1973.], The Hague, Netherlands: W. Junk. 99-102.
Thuoc NH, Tinh NH, Nhu DX, Thong NW, Thach HN, 1978. (Anh huo'ng cua anh sang va nhiet do den sinh truong va quang hop cua beo dau. (Vliyanie sveta i temperatury na rost i fotosintez Azolla pinnata.)). In: Khoa Hoc va Kythuat Nong Nghiep, 2 91-95.
USDA-ARS, 2005. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysimple.aspx
Distribution MapsTop of page
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