{{Short description|Subfamily of aquatic plants}} {{for|the Chinese film|Duckweed (film)}} {{Use dmy dates|date=January 2020}} {{Automatic taxobox | image = Duckweeds.jpg | image_caption = Close-up of two different duckweed types: ''Spirodela polyrrhiza'' and ''Wolffia globosa'': The latter are less than 2 mm long. | taxon = Lemnoideae | authority = | subdivision_ranks = Genera | subdivision = * ''Lemna'' * ''Spirodela'' * ''Wolffia'' * ''Wolffiella'' | synonyms = Lemnaceae }} '''Lemnoideae''' is a subfamily of flowering aquatic plants, known as '''duckweeds''', '''water lentils''', or '''water lenses'''. They float on or just beneath the surface of still or slow-moving bodies of fresh water and wetlands. Also known as '''bayroot''', they arose from within the arum or aroid family (Araceae),<ref name="tam">{{cite journal |author1=Sheh-May Tam |author2=Peter C. Boyce |author3=Tim M. Upson |author4=Denis Barabé |author5=Anne Bruneau |author6=Felix Forest |author7=John S. Parker | year = 2004 | title = Intergeneric and infrafamilial phylogeny of subfamily Monsteroideae (Araceae) revealed by chloroplast <011>trnL-F sequences | journal = American Journal of Botany| volume = 91 | issue = 3 | pages = 490–498 | doi = 10.3732/ajb.91.3.490 | doi-access=free | pmid=21653404}}</ref> so often are classified as the subfamily Lemnoideae within the family Araceae. Other classifications, particularly those created prior to the end of the twentieth century, place them as a separate family, '''Lemnaceae'''.
These plants have a simple structure, lacking an obvious stem or leaves. The greater part of each plant is a small organized "thallus" or "frond" structure only a few cells thick, often with air pockets (aerenchyma) that allow it to float on or just under the water surface. Depending on the species, each plant may have no root or may have one or more simple rootlets.<ref>{{cite book |last=Sculthorpe |first=Cyril Duncan |year=1985 |title=The Biology of Aquatic Vascular Plants |publisher=Koeltz Scientific Books|isbn=978-3-87429-257-3 |url=https://archive.org/details/biologyofaquatic0000scul |url-access=registration}}</ref>
Reproduction is mostly by asexual budding (vegetative reproduction), which occurs from a meristem enclosed at the base of the frond. Occasionally, three tiny "flowers" consisting of two stamens and a pistil are produced, by which sexual reproduction occurs. Some view this "flower" as a pseudanthium, or reduced inflorescence, with three flowers that are distinctly either female or male and which are derived from the spadix in the Araceae. Evolution of the duckweed inflorescence remains ambiguous due to the considerable evolutionary reduction of these plants from their earlier relatives.
The flower of the duckweed genus ''Wolffia'' is the smallest known, measuring merely 0.3 mm long.<ref>{{cite book|last=Landolt|first=Elias|title=Biosystematic investigations in the family of duckweeds (Lemnaceae) Vol. 2: The family of Lemnaceae: a monographic study. – Morphology, karyology, ecology, geographic distribution, nomenclature, descriptions|year=1986|publisher=Eidgenössische Technische Hochschule Zürich|location=Zürich}}</ref> The fruit produced through this occasional reproduction is a utricle, and a seed is produced in a bag containing air that facilitates flotation.
== Duckweed in natural environments == One of the more important factors influencing the distribution of wetland plants, and aquatic plants in particular, is nutrient availability.<ref>{{cite book |last=Keddy |first=Paul A. |year=2010 |chapter=Fertility |title=Wetland Ecology: Principles and conservation |edition=2nd |publisher=Cambridge University Press |isbn=978-0-521-73967-2 |page=79 |chapter-url=https://books.google.com/books?id=eVeaSqFy2VgC&pg=PA79 |access-date=7 May 2012}}</ref> Duckweeds tend to be associated with fertile, even eutrophic conditions. They can be spread by sticking to the feathers of waterfowl and the skin or fur of other amphibious animals, and thus transported inadvertently to new bodies of water.<ref>{{cite book |last=Hutchinson |first=G. Evelyn |year=1975 |title=A Treatise on Limnology |volume=3: Limnological botany |publisher=John Wiley & Sons |location=New York, NY}}</ref> The plants may also be transported by flooding or other moving water. In water bodies with constant currents or overflow, the plants are carried down the channels and do not typically proliferate greatly, as they prefer still waters. However, in some locations, a cyclical pattern exists, driven by weather patterns, in which the plants proliferate greatly during periods of low water movement before they are carried away as rainy periods ensue.
Duckweed is an important, high-protein food source for waterfowl and many species of fish.{{citation needed|date=September 2025}} The tiny plants provide cover for the vulnerable fry and tadpoles of many fishes and amphibians. The plants are used as shelter by pond species, such as bullfrogs and newts, and fish such as bluegills. They also provide shade and, although frequently confused with them, can reduce certain light-generated growths of photoautotrophic algae.
== Use as human food crop == Duckweed is consumed in some parts of Southeast Asia, namely Laos, Thailand, and Myanmar.<ref>{{cite journal |last1=Appenroth |first1=K.J. |last2=Sree |first2=K.S. |last3=Böhm |first3=V. |last4=Hammann |first4=S. |last5=Vetter |first5=W. |last6=Leiterer |first6=M. |last7=Jahreis |first7=G. |year=2017 |title=Nutritional value of duckweeds (''Lemnaceae'') as human food |journal=Food Chemistry |volume=217 |pages=266–273 |doi=10.1016/j.foodchem.2016.08.116 |pmid=27664634|s2cid=6617534 }}</ref> In addition, it is also cultivated as a vegetable in Israel.<ref>{{Cite web |title=Lemna Gibbous Duckweed, Swollen duckweed, Windbags, Duckweed PFAF Plant Database |url=https://pfaf.org/user/Plant.aspx?LatinName=Lemna |access-date=2023-01-04 |website=pfaf.org}}</ref> It produces more protein per square meter than soybeans, contains vitamins (such as B12), minerals, and carotenoids (lutein, beta-carotene), so it is sometimes cited as a significant potential food source for humans.<ref>{{cite web |last=Landesman |first=Louis |title=Dr. Wastewater's duckweed application |url=http://geocities.com/RainForest/Canopy/3631/ |access-date=31 January 2012 |archive-url=https://web.archive.org/web/20091027041958/http://geocities.com/RainForest/Canopy/3631/ |archive-date=27 October 2009 }}</ref>
Some initial investigations into what extent duckweed could be introduced to European markets have shown little consumer objection to the idea.<ref>{{cite journal |last1=de Beukelaar |first1=Myrthe F. |last2=Zeinstra |first2=Gertrude G. |last3=Mes |first3=Jurriaan J. |last4=Fischer |first4=Arnout R.H. |year=2019 |title=Duckweed as human food: The influence of meal context and information on duckweed acceptability of Dutch consumers |journal=Food Quality and Preference |volume=71 |issue=1 |pages=76–86 |doi=10.1016/j.foodqual.2018.06.005 |doi-access=free}}</ref> NASA's Caves of Mars Project identified duckweed as a top candidate for Martian food production projects.<ref>{{cite web |title=Flat crops for Mars |website=The caves of Mars (highmars.org) |url=http://www.highmars.org/niac/niac04.html |access-date=11 January 2022 |archive-url=https://web.archive.org/web/20070701234427/http://www.highmars.org/niac/niac04.html |archive-date=1 July 2007}}</ref><ref>{{cite web |title=Duckweed, or Water Lentils, as novel crop or protein source |website=The charm of Duckweed |url=https://thecharmofduckweed.org/Food}}</ref>
==Invasive species== Despite some of these benefits, because duckweed thrives in high-nutrient wetland environments, the plants can be seen as a nuisance species when conditions favor excessive proliferation in environments that are traditionally low in nutrients or oligotrophic.
One example of this problem occurs within the Everglades, a mostly oligotrophic environment, when excess chemicals (that include fertilizers) are carried by storm runoff, or surface runoff, into its waterways.<ref>{{cite book |last1=Cunningham |first1=William |last2=Cunningham |first2=Mary |year=2015 |title=Environmental Science: A global concern |edition=13th |publisher=McGraw-Hill Education |location=New York, NY |isbn=978-1-259-25572-4 |page=415}}</ref>
Urban runoff and agricultural pollution then begin to introduce increased levels of nutrients into the surrounding wetlands and waterways, which can cause a disruption to native ecology. These conditions allow for the invasion of a fast growing species such as duckweed to establish themselves, spread, and displace other native species such as sawgrass, and over time, result in widespread changes to the ecology of native sawgrass and slough habitats within the Everglades.<ref>{{cite book |last1=Finkl |first1=Charles |last2=Makowski |first2=Christopher |year=2017 |title=Coastal Wetlands: Alteration and remediation |publisher=Springer |place=Cham, Switzerland |isbn=978-3-319-56178-3 |page=16 |url=https://books.google.com/books?id=YG0tDwAAQBAJ&pg=PA3 |access-date=1 January 2021}}</ref>
== Taxonomy == thumb|right|Duckweeds belong to the order Alismatales and the family Araceae. (a) is a phylogenetic tree based on ribulose-1, 5-bisphosphate carboxylase large-subunit genes. (b) is a schematic ventral view of ''Spirodela'', to show the clonal, vegetative propagation of duckweeds. Daughter fronds (F1) originate from the vegetative node (No), from the mother frond F0 and remain attached to it by the stipule (Sti), which eventually breaks off, thereby releasing a new plant cluster. Daughter fronds may already initiate new fronds (F2) themselves before full maturity. Roots are attached at the prophyllum (P). (c) shows the progressive reduction from a leaf-like body with several veins and unbranched roots to a thallus-like morphology in the Lemnoideae. The duckweeds have long been a taxonomic mystery, and usually have been considered to be their own family, the Lemnaceae. They primarily reproduce asexually. Flowers, if present at all, are small. Roots are either very much reduced, or absent entirely. They were suspected of being related to the Araceae as long ago as 1876, but until the advent of molecular phylogeny, testing this hypothesis was difficult.
Starting in 1995, studies began to confirm their placement in the Araceae and since then, most systematists have considered them to be part of that family,<ref name=cabrera/> although in 2021, recognition again as a separate family was proposed.<ref name=AcosAppeBoriEdel21>{{Cite journal |last1=Acosta |first1=Kenneth |last2=Appenroth |first2=Klaus J. |last3=Borisjuk |first3=Ljudmilla |last4=Edelman |first4=Marvin |last5=Heinig |first5=Uwe |last6=Jansen |first6=Marcel A. K. |last7=Tokitaka |first7=Oyama |last8=Pasaribu |first8=Buntora |last9=Schubert |first9=Ingo |last10=Sorrels |first10=Shawn |last11=Sree |first11=K. Sowjanya |last12=Xu |first12=Shuqing |last13=Michael |first13=Todd P. |last14=Lam |first14=Eric |date=2021 |title=Return of the Lemnaceae: duckweed as a model plant system in the genomics and postgenomics era |journal=The Plant Cell |volume=33 |issue=10 |pages=3207–3234 |doi=10.1093/plcell/koab189 |pmid=34273173 |name-list-style=amp |pmc=8505876 }}</ref>
Their position within their family has been slightly less clear; however, several twenty-first century studies place them in the position shown below.<ref name=cabrera> {{cite journal | author1 = Cabrera, Lidia I. | author2 = Salazar, Gerardo A. | author3 = Chase, Mark W. | author4 = Mayo, Simon J. | author5 = Bogner, Josef | author6 = Dávila, Patricia | year = 2008 | title = Phylogenetic relationships of aroids and duckweeds (Araceae) inferred from coding and noncoding plastid DNA | journal = American Journal of Botany | volume = 95 | issue = 9 | pages = 1153–1165 | pmid = 21632433 | doi = 10.3732/ajb.0800073 | bibcode = 2008AmJB...95.1153C | doi-access = free }} </ref> Although they are in the same family as ''Pistia'', another aquatic plant, they are not closely related.<ref name=cabrera/> {{clade |label1= Araceae <!-- stem --> |1={{clade |1={{clade |1=Gymnostachydoideae |2=Orontioideae (skunk cabbages and golden club) }} |2={{clade |1='''Lemnoideae''' (duckweeds) |2=''most of the rest of the family'' Araceae }} }} }}
The genera of duckweeds are: ''Spirodela'', ''Landoltia'', ''Lemna'', ''Wolffiella'', and ''Wolffia''.
Duckweed genome sizes have a ten-fold range (150~1,500 MB), potentially representing diploids to octaploids. The ancestral genus of ''Spirodela'' has the smallest genome size (150 MB, similar to ''Arabidopsis thaliana''), while the most derived genus, ''Wolffia'', contains plants with the largest genome size (1,500 MB).<ref>{{cite journal |author1=Wang, Wenqin |author2=Kerstetter, Randall A. |author3=Michael, Todd P. |title=Evolution of Genome Size in Duckweeds (''Lemnaceae'')|journal=Journal of Botany|year=2011|volume=2011|doi=10.1155/2011/570319|issn=2090-0120|issue=570319|pages=1–9|doi-access=free}}</ref> DNA sequencing has shown that ''Wolffiella'' and ''Wolffia'' are more closely related than the others. ''Spirodela'' is at the basal position of the taxon, followed by ''Lemna'', ''Wolffiella'', and ''Wolffia'', which is the most derived.<ref>{{cite journal|last=Wang|first=Wenqin|author2=Messing, Joachim |author3=Badger, Jonathan H. |year=2011 |title=High-Throughput sequencing of three ''Lemnoideae'' (duckweeds) chloroplast genomes from total DNA |journal=PLOS ONE |volume=6 |issue=9 |article-number =e24670 |doi=10.1371/journal.pone.0024670 |doi-access=free |pmc=3170387 |pmid=21931804|bibcode=2011PLoSO...624670W}}</ref> {{clade |1={{clade |1=''Spirodela'' |2={{clade |1=''Lemna'' |2={{clade |1=''Wolffiella'' |2=''Wolffia'' }} }} }} }}
To identify different duckweed genomes, a DNA-based molecular identification system was developed based on seven plastid-markers proposed by the Consortium for the Barcode of Life.<ref>{{cite journal |last1=Hollingsworth |first1=P.M. |display-authors=etal |date=July 2009 |title=A DNA barcode for land plants |journal=Proceedings of the National Academy of Sciences |volume=106 |issue=31 |pages=12794–12797 |doi=10.1073/pnas.0905845106 |pmid=19666622 |pmc=2722355 |doi-access=free |url=http://xa.yimg.com/kq/groups/18463231/1250370658/name/A+DNA+barcode+for+land+plants.pdf |access-date=2 August 2012}}</ref> The ''atpF-atpH'' non-coding spacer was chosen as a universal DNA barcoding marker for species-level identification of duckweeds.<ref>{{cite journal|last=Wang|first=Wenqin|author2=Wu, Yongrui |author3=Yan, Yiheng |author4=Ermakova, Marina |author5=Kerstetter, Randall |author6= Messing, Joachim |year=2010 |title=DNA barcoding of the ''Lemnaceae'', a family of aquatic monocots |journal=BMC Plant Biology |volume=10 |issue=1 |page=205 |doi=10.1186/1471-2229-10-205 |pmid=20846439 |pmc=2956554 |bibcode=2010BMCPB..10..205W |doi-access=free }}</ref>
==Fossil record== Extinct free-floating aquatic plants and pollen with affinities to the Lemnoideae first appear in the fossil record during the Late Cretaceous (Maastrichtian) as evidenced by floating leaves described as ''Aquaephyllum auriculatum'' from Patagonia, Argentina, and the lemnoid pollen genus ''Pandaniidites''.<ref name=Gallego>{{cite journal |author1=Gallego, J. |author2=Gandolfo, M.A. |author3=Cúneo, N.R. |author4=Zamaloa, M.C. |year=2014 |title=Fossil Araceae from the upper Cretaceous of Patagonia, Argentina, with implications on the origin of free-floating aquatic aroids |journal=Review of Palaeobotany and Palynology|volume=211 |pages=78–86 |doi=10.1016/j.revpalbo.2014.08.017 |bibcode=2014RPaPa.211...78G |hdl=11336/36506 |hdl-access=free }}</ref>
Fossils of floating leaves with rootlets from the Paleocene of southern Saskatchewan, Canada, that were originally described as ''Lemna'' (''Spirodela'') ''scutata'' by John William Dawson in 1885, have been redescribed as ''Limnobiophyllum''.<ref name=Kvacek>{{cite journal |author=Kvaček, Z. |year=1995 |title=''Limnobiophyllum'' {{small|(Krassilov)}} – A fossil link between Araceae and Lemnaceae |journal=Aquatic Botany |volume=50 |pages=49–61|doi=10.1016/0304-3770(94)00442-O }}</ref> In addition to western North America, ''Limnobiophyllum'' has been reported from the Paleocene of eastern Russia and the Miocene of the Czech Republic.<ref name=Kvacek /> Unusually complete specimens from the Paleocene of Alberta, Canada, range from single leaves up to about {{cvt|4|cm|in}} in diameter to rosettes of up to four leaves, some of which were connected to adjacent plants by stolons, and a few of which bear remains of flowers with anthers that contain ''Pandaniidites'' pollen.<ref name=Stockey>{{cite journal |author1=Stockey, R.A. |author2=Hoffman, G.L. |author3=Rothwell, G.W. |year=1997 |title=The fossil monocot ''Limnobiophyllum scutatum'': Resolving the phylogeny of Lemnaceae |journal=American Journal of Botany |volume=84 |issue=3 |pages=355–368|doi=10.2307/2446009 |jstor=2446009 |pmid=21708589 |s2cid=20957240 |doi-access=free }}</ref> Occurrences of lemnoid seeds described as ''Lemnospermum'' have also been reported.<ref name=Kvacek />
== Research and applications == Research and applications of duckweeds are promoted by two international organizations, The International Lemna Association<ref>{{cite web |title=The International Lemna Association (ILA) |type=official website |url=http://www.internationallemnaassociation.org/|archive-url=https://web.archive.org/web/20121130023705/http://www.internationallemnaassociation.org/|url-status=usurped|archive-date=30 November 2012}}</ref> and the International Steering Committee on Duckweed Research and Applications.<ref>{{cite web |title=International Steering Committee on Duckweed Research and Applications (ISCDRA) |type=official website |url=http://lemnapedia.org/wiki/ISCDRA}}</ref>
In July 2008, the U.S. Department of Energy (DOE) Joint Genome Institute announced that the Community Sequencing Program would fund sequencing of the genome of the giant duckweed, ''Spirodela polyrhiza''. This was a priority project for DOE in 2009. The research was intended to facilitate new biomass and bioenergy programs.<ref>{{cite web |title=Duckweed genome sequencing has global implications |date=8 July 2008 |website=E! Science News (Esciencenews.com) |url=http://esciencenews.com/articles/2008/07/08/duckweed.genome.sequencing.has.global.implications |access-date=13 November 2011 |archive-date=24 May 2011 |archive-url=https://web.archive.org/web/20110524015107/http://esciencenews.com/articles/2008/07/08/duckweed.genome.sequencing.has.global.implications }}</ref> The results were published in February 2014. They provide insight into how this plant is adapted to rapid growth and an aquatic lifestyle.<ref>{{cite journal |author1=Wang, W. |display-authors=etal |year=2014 |title=The ''Spirodela polyrhiza'' genome reveals insights into its neotenous reduction fast growth and aquatic lifestyle |journal=Nature Communications |volume=5 |article-number=3311 |doi=10.1038/ncomms4311 |pmid=24548928 |pmc=3948053 |doi-access=free |bibcode=2014NatCo...5.3311W }}</ref>
===Potential clean energy source=== Duckweed is being studied by researchers around the world as a possible source of clean energy. In the U.S., in addition to being the subject of study by the DOE, both Rutgers University and North Carolina State University have ongoing projects to determine whether duckweed might be a source of cost-effective, clean, renewable energy.<ref>{{cite web |last=Michael|first=Todd P. |year=2008 |title=Genome sequencing of the duckweed ''Spirodela polyrhiza'': A biofuels, bioremediation, and carbon cycling crop |publisher=Rutgers University |url=http://lemna.rutgers.edu/Michael_duckweed_JGIDOE_2008_final.pdf |access-date=7 May 2012|archive-url=https://web.archive.org/web/20111003092955/http://lemna.rutgers.edu/Michael_duckweed_JGIDOE_2008_final.pdf|archive-date=3 October 2011}}</ref><ref>{{cite web|url=http://www.ncsu.edu/research/results/vol8n2/09.html |title=Researchers Find Fuel in Odd Places |publisher=Ncsu.edu |access-date=13 November 2011}}</ref> Duckweed is a good candidate as a biofuel because it grows rapidly, produces five to six times as much starch as corn per unit of area, and does not contribute to global warming.<ref>{{cite web |last=Sims |first=Bryan |date=n.d. |title=Duckweed quacks volumes of potential |website=Biomassmagazine.com |url=http://www.biomassmagazine.com/article.jsp?article_id=2714&q=&page=all |access-date=13 November 2011}}</ref><ref>{{cite web |title=Duckweed a possible solution to energy needs, researchers say |publisher=Pressofatlanticcity.com |date=3 May 2010 |url=http://www.pressofatlanticcity.com/news/press/cumberland/article_4ae59e12-56f1-11df-a5d8-001cc4c002e0.html |access-date=13 November 2011}}</ref> The rapid nature of duckweed has shown that it can double biomass within four and a half days.<ref>{{Cite journal |last1=Faizal |first1=Ahmad |last2=Sembada |first2=Anca Awal |last3=Priharto |first3=Neil |date=2021-01-01 |title=Production of bioethanol from four species of duckweeds (Landoltia punctata, Lemna aequinoctialis, Spirodela polyrrhiza, and Wolffia arrhiza) through optimization of saccharification process and fermentation with Saccharomyces cerevisiae |url= |journal=Saudi Journal of Biological Sciences |volume=28 |issue=1 |pages=294–301 |doi=10.1016/j.sjbs.2020.10.002 |issn=1319-562X |pmc=7785427 |pmid=33424309|bibcode=2021SJBS...28..294F }}</ref><ref>{{Cite journal |last1=Ziegler |first1=P. |last2=Adelmann |first2=K. |last3=Zimmer |first3=S. |last4=Schmidt |first4=C. |last5=Appenroth |first5=K.-J. |date=2014-05-06 |editor-last=Keurentjes |editor-first=J. |title=Relative in vitro growth rates of duckweeds ( L emnaceae) – the most rapidly growing higher plants |url=|journal=Plant Biology |language=en |volume=17 |issue=s1 |pages=33–41 |doi=10.1111/plb.12184 |pmid=24803032 |issn=1435-8603}}</ref><ref>{{Cite journal |last1=Guo |first1=Ling |last2=Fang |first2=Yang |last3=Jin |first3=Yanling |last4=He |first4=Kaize |last5=Zhao |first5=Hai |date=2023-11-01 |title=High starch duckweed biomass production and its highly-efficient conversion to bioethanol |url= |journal=Environmental Technology & Innovation |volume=32 |article-number=103296 |doi=10.1016/j.eti.2023.103296 |issn=2352-1864|doi-access=free |bibcode=2023EnvTI..3203296G }}</ref> Duckweed removes carbon dioxide from the atmosphere, and it may have value for climate change mitigation.<ref>{{cite web |title=Carbon Neutral Energy |website=American Energy Independence |url=http://www.americanenergyindependence.com/carbonneutral.aspx |access-date=13 November 2011 |archive-date=27 September 2011 |archive-url=https://web.archive.org/web/20110927223526/http://www.americanenergyindependence.com/carbonneutral.aspx }}</ref>
===Filtration of contaminants and nutrients=== The plants can provide nitrate removal, if cropped, and the duckweeds are important in the process of bioremediation because they grow rapidly, absorbing excess mineral nutrients, particularly nitrogen and phosphates. For these reasons, they are touted as water purifiers of untapped value.<ref>{{cite web |title=Duckweed wastewater treatment and reuse for fodder (West Bank) |website=Idrc.ca |url=http://www.idrc.ca/es/ev-6314-201-1-DO_TOPIC.html |access-date=13 November 2011 |archive-url=https://web.archive.org/web/20110608214049/http://www.idrc.ca/es/ev-6314-201-1-DO_TOPIC.html |archive-date=8 June 2011 }}</ref>
The Swiss Department of Water and Sanitation in Developing Countries, associated with the Swiss Federal Institute for Environmental Science and Technology, asserts that as well as the food and agricultural values, duckweed also may be used for wastewater treatment to capture toxins and for odor control, and that if a mat of duckweed is maintained during harvesting for removal of the toxins captured thereby, it prevents the development of algae and controls the breeding of mosquitoes.<ref>{{cite journal |last=Iqbal |first=Sascha |date=March 1999 |title=Duckweed aquaculture: Potentials, possibilities, and limitations for combined wastewater treatment and animal feed production in developing countries |journal=SANDEC Report |volume=6 |issue=99 |url=http://www.eawag.ch/forschung/sandec/publikationen/wra/dl/duckweed.pdf |access-date=31 January 2012}}</ref> The same publication provides an extensive list of references for many duckweed-related topics.
These plants also may play a role in conservation of water because a cover of duckweed will reduce evaporation of water when compared to the rate of a similarly sized water body with a clear surface.
Duckweed also functions as a bioremediator by effectively filtering contaminants such as bacteria, nitrogen, phosphates, and other nutrients from naturally occurring bodies of water, constructed wetlands, and wastewater.<ref>{{cite press release |title=Duckweed genome sequencing has global implications. Pond scum can undo pollution, fight global warming and alleviate world hunger |publisher=Rutgers University |date=8 July 2008 |url=https://www.rutgers.edu/news/duckweed-genome-sequencing-has-global-implications |access-date=10 March 2022}}</ref><ref>{{cite web |author=Cross, John W. |title=Practical duckweed: Application areas and sponsors |website=Mobot.org |url=http://www.mobot.org/jwcross/duckweed/practical_duckweed.htm |access-date=13 November 2011 |archive-date=25 September 2016 |archive-url=https://web.archive.org/web/20160925121914/http://www.mobot.org/jwcross/duckweed/practical_duckweed.htm }}</ref><ref>{{cite web |last=Knibb |first=Wayne |date=July 2001 – June 2004 |title=Bioremediation of aquaculture waste and degraded waterways using finfish |publisher=Queensland Government |place=Australia |series=Department of Primary Industries & Fisheries Tools |url=http://www2.dpi.qld.gov.au/far/9212.html|access-date=6 February 2012 |archive-url=https://web.archive.org/web/20071020015703/http://www2.dpi.qld.gov.au/far/9212.html |archive-date=20 October 2007}}</ref>
<gallery> File:LentejasDeAgua.jpg|Common duckweed in Galicia, Spain File:Lemna minor1.jpg|''Lemna minor'' File:Lemna trisulca0.jpg|''Lemna trisulca'' File:L gibba3.jpg|''Lemna gibba'' File:Spirodela polyrrhiza marais poitevin.jpg|''Spirodela polyrhiza'' File:Curve of duckweed covered water edged with several bald cypress trees.JPG|Duckweed-covered water edged with several bald cypress trees File:Орусъярви, озеро Мюллюлампи сверху.jpg|Myllylampi lake with duckweed "islands" photographed from above. Orusjärvi, Pitkyarantsky District, Karelia, Russia. File:Duckweed-covered pond near Chodzież, Poland.jpg|Duckweed-covered pond near Chodzież, Poland </gallery>
A start-up, microTERRA, based in Mexico has attempted to use duckweed to clean the water in privately owned aquaculture farms. The plants use nitrogen and phosphorus produced from fish waste as fertilizer, while simultaneously cleaning the water as it grows. The water can then be reused by the aquaculture farmers, and the duckweed, which has a 35-42% protein content, can be harvested as a source of sustainable plant-based protein.<ref>{{Cite web|title=3 Eco-Innovators Tackling Pollution and Climate Change|url=https://magazine.columbia.edu/article/3-eco-innovators-tackling-pollution-and-climate-change|access-date=2021-11-24|website=Columbia Magazine|language=en}}</ref>
== See also == * Azolla * Hyperaccumulators table – 3 * Neuston * Phytoremediation * Smallest organisms * Wolffia globosa
== References == {{reflist|colwidth=25em}}
== External links == {{Wikispecies}} {{Commons category|Lemnoideae}} * {{cite web |first=John W. |last=Cross |title=The charms of duckweed |website=mobot.org |url=http://www.mobot.org/jwcross/duckweed/ }} * {{cite web |first=Wayne |last=Armstrong |author-link=Wayne P. Armstrong |date=n.d. |title=W.P. Armstrong's exposition on and macrophotography of the ''Lemnaceae'' and allies (duckweeds) |website=Wayne's Word |series=Natural History |publisher=Palomar College |place=San Marcos, CA |url=https://www2.palomar.edu/users/warmstrong/1wayindx.htm |access-date=2022-10-16 }} * {{cite web |title=''Lemnaceae'' |website=delta-intkey.com |url=http://delta-intkey.com/angio/www/lemnacea.htm }} : {{small|''derived from''}} : {{cite book |author1=Watson, L. |author2=Dallwitz, M.J. |name-list-style=amp |orig-date=1992 |date=3 May 2006 |title=The Families of Flowering Plants: Descriptions, illustrations, identification, information retrieval |via=delta-intkey.com |url=http://delta-intkey.com/angio/ |archive-url=https://web.archive.org/web/20070103200438/http://delta-intkey.com/angio/ |archive-date=2007-01-03 }} * {{cite web |title=Duckweed growth inhibition test |department=List of Standards |website=lemnatec.com |url=http://www.lemnatec.com/faq/standards-faq |archive-url=https://archive.today/20130127193420/http://www.lemnatec.com/faq/standards-faq |archive-date=2013-01-27 }} * {{cite web |title=''Spirodela'' genomics |series=SpirodelaBase |type=research lab site |publisher=Rutgers University |url=http://www.waksman.rutgers.edu/spirodela/home |access-date=3 August 2012 |archive-date=10 March 2014 |archive-url=https://web.archive.org/web/20140310202510/http://www.waksman.rutgers.edu/spirodela/home }}
{{Bioenergy}} {{Taxonbar|from=Q161429|from2=Q14293890}}
Category:Lemnoideae Category:Aquatic plants Category:Alismatales subfamilies Category:Phytoremediation plants