Azolla filiculoides

{{Short description|Species of plant}}

{{Speciesbox

|image=Water Fern Azolla filiculoides (6165580451).jpg

|status= {{TNCStatus}}

|status_system=TNC

|genus=Azolla

|species=filiculoides

|authority=Lam.{{cite journal |vauthors=Lamarck JB |author-link1=Jean-Baptiste Lamarck |journal=Encyclopédie Méthodique, Botanique |volume=1 |issue=1 |pages=343 |date=1783 |url=http://www.tropicos.org/Name/40023609 |title=Name - Azolla Lam. |quote=Annotation: a sp. nov. reference for Azolla filiculoides
Type Specimens HT: Azolla filiculoides |publisher=Missouri Botanical Garden |location=Saint Louis, Missouri |access-date=February 19, 2010 |archive-date=October 19, 2012 |archive-url=https://web.archive.org/web/20121019091519/http://www.tropicos.org/Name/40023609 |url-status=live }}{{cite web |url=http://www.nobanis.org/files/factsheets/Azolla_filiculoides.pdf |title=NOBANIS -- Invasive Alien Species Fact Sheet -- Azolla filiculoides |vauthors=Hussner A |location=Heinrich Heine University, Düsseldorf |year=2006 |work=Online Database of the North European and Baltic Network on Invasive Alien Species |access-date=February 19, 2010 |archive-date=June 23, 2007 |archive-url=https://web.archive.org/web/20070623125951/http://www.nobanis.org/files/factsheets/Azolla_filiculoides.pdf |url-status=live }}

|synonyms=*Azolla arbuscula Desv.

• Azolla caroliniana Willd.
• Azolla japonica Franch. & Sav.
• Azolla magellanica Willd.
• Azolla microphylla Kaulf.
• Azolla pinnata var. japonica (Franch. & Sav.) Franch. & Sav.
• Azolla squamosa Molina

|synonyms_ref={{Cite web |url=http://www.tropicos.org/Name/26602847?tab=synonyms |title=Tropicos |access-date=2014-02-06 |archive-date=2014-02-23 |archive-url=https://web.archive.org/web/20140223071348/http://www.tropicos.org/Name/26602847?tab=synonyms |url-status=live }}

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Azolla filiculoides (water fern) is a species of aquatic fern. It is native to warm temperate and tropical regions of the Americas, and has been introduced to Europe, North and sub-Saharan Africa, China, Japan, New Zealand, the Caribbean, and Hawaii.Azolla filiculoides

(water fern) - Invasive Species Compendium https://www.cabi.org/isc/datasheet/8119 {{Webarchive|url=https://web.archive.org/web/20220119203849/https://www.cabi.org/isc/datasheet/8119 |date=2022-01-19 }}

It is a floating aquatic fern with very fast growth, capable of spreading over the surfaces of lakes to give complete coverage of the water in only a few months. Each individual plant is 1–2 cm across, green tinged pink, orange, or red at the edges, branching freely, and breaking into smaller sections as it grows. It is not tolerant of cold temperatures; in temperate regions it largely dies back in winter, surviving by means of submerged buds. It harbors the diazotrophic organism Anabaena azollae in specialized leaf pockets. This ancient symbiosis allows A. azollae to fix nitrogen from the air and contribute to the fern's metabolism.{{cite journal |vauthors=Brouwer P, Bräutigam A, Buijs VA, Tazelaar AO, van der Werf A, Schlüter U, Reichart GJ, Bolger A, Usadel B, Weber AP, Schluepmann H |display-authors=6 |title=Azolla Ferns without Nitrogen Fertilizer |journal=Frontiers in Plant Science |volume=8 |pages=442 |date=2017-03-31 |pmid=28408911 |pmc=5374210 |doi=10.3389/fpls.2017.00442 |doi-access=free}}{{ cite book |last=Meeks |first=John C. |name-list-style=vanc |chapter=Physiological Adaptations in Nitrogen-fixing Nostoc–PlantSymbiotic Associations |date=2009 |title=Prokaryotic Symbionts in Plants |pages=181–205 |editor-last=Pawlowski |editor-first=Katharina |series=Microbiology Monographs|volume=8 |place=Berlin, Heidelberg |publisher=Springer |doi=10.1007/7171_2007_101 |isbn=978-3-540-75460-2 }}

Fossil records from as recent as the last interglacials are known from several locations in Europe (Hyde et al. 1978). 50 million years ago, a species similar to A. filiculoides may have played a pivotal role in cooling the planet in what is known as the Azolla event.{{Cite web |date=2018-07-11 |title=Can A Tiny Fern Help Fight Climate Change and Cut Fertilizer Use? |url=https://e360.yale.edu/digest/can-a-tiny-fern-help-fight-climate-change-and-cut-fertilizer-use-azolla |url-status=live |access-date=2021-09-27 |website=Yale E360 |language=en-US |archive-url=https://web.archive.org/web/20201024175716/https://e360.yale.edu/digest/can-a-tiny-fern-help-fight-climate-change-and-cut-fertilizer-use-azolla |archive-date=2020-10-24}}

A. filiculoides was one of the first two fern species with a reference genome published.{{cite journal |vauthors=Li FW, Brouwer P, Carretero-Paulet L, Cheng S, de Vries J, Delaux PM, Eily A, Koppers N, Kuo LY, Li Z, Simenc M, Small I, Wafula E, Angarita S, Barker MS, Bräutigam A, dePamphilis C, Gould S, Hosmani PS, Huang YM, Huettel B, Kato Y, Liu X, Maere S, McDowell R, Mueller LA, Nierop KG, Rensing SA, Robison T, Rothfels CJ, Sigel EM, Song Y, Timilsena PR, Van de Peer Y, Wang H, Wilhelmsson PK, Wolf PG, Xu X, Der JP, Schluepmann H, Wong GK, Pryer KM |display-authors=6 |title=Fern genomes elucidate land plant evolution and cyanobacterial symbioses |language=En |journal=Nature Plants |volume=4 |issue=7 |pages=460–472 |date=July 2018 |pmid=29967517 |pmc=6786969 |doi=10.1038/s41477-018-0188-8|bibcode=2018NatPl...4..460L }}