# Najas

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{{Short description|Genus of aquatic plants}}
{{Redirect|Caulinia|the defunct legume genus ''Caulinia'' Moench|Kennedia}}
{{For|the non-profit organization|National Association of Japan-America Societies}}
{{Automatic taxobox
|image = Illustration Najas marina0.jpg
|image_caption = ''Najas marina''<ref>Otto Wilhelm Thomé. Flora von Deutschland, Österreich und der Schweiz 1885, Gera, Germany</ref>
|taxon = Najas
|authority = [L.](/source/Carl_Linnaeus)
|synonyms_ref = <ref name=wet>[http://apps.kew.org/wcsp/synonomy.do?name_id=308218 Kew World Checklist of Selected Plant Families]</ref>
|synonyms = 
* ''Fluvialis'' <small>Ség</small>
* ''Caulinia'' <small>Willd.</small>
* ''Ittnera'' <small>C.C.Gmel.</small>
}}

'''''Najas''''', the '''water-nymphs'''<ref>{{PLANTS |id=NAJAS|taxon=Najas |accessdate=16 July 2015 }}</ref> or '''naiads''', is a [genus](/source/genus) of [aquatic plant](/source/aquatic_plant)s. It is [cosmopolitan](/source/cosmopolitan_(distribution)) in distribution, first described for modern science by [Linnaeus](/source/Carl_Linnaeus) in 1753. Until 1997, it was rarely placed in the [Hydrocharitaceae](/source/Hydrocharitaceae),<ref name=tanaka>{{citation |doi=10.1007/BF02524931 |title=Phylogeny of the family hydrocharitaceae inferred fromrbcL andmatK gene sequence data |year=1997 |last1=Tanaka |first1=Norio |last2=Setoguchi |first2=Hiroaki |last3=Murata |first3=Jin |journal=Journal of Plant Research |volume=110 |issue=3 |pages=329–337 |bibcode=1997JPlR..110..329T |s2cid=10939773 }}</ref><ref name=les>{{citation |title=Phylogenetic studies in Alismatidae, II: Evolution of Marine Angiosperms (Seagrasses) and Hydrophily |year=1997 |last1=Les |first1=DH |last2=Cleland |first2=MA |last3=Waycott |first3=M |journal=Systematic Botany |volume=22 |issue=3 |pages=443 |doi=10.2307/2419820 |jstor=2419820 |bibcode=1997SysBo..22..443L }}</ref><ref>[https://web.archive.org/web/20000712110354/http://www.ars-grin.gov/cgi-bin/npgs/html/gnlist.pl?561 Genera of Hydrocharitaceae], ''GRIN Taxonomy for Plants''</ref><ref name="apg2003">Angiosperm Phylogeny Group (2003). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II". ''Botanical Journal of the Linnean Society'' '''141'''(4): 399-436. (Available online: [https://archive.today/20120919163719/http://www3.interscience.wiley.com/journal/118872219/abstract Abstract] | [https://archive.today/20121205102805/http://www3.interscience.wiley.com/cgi-bin/fulltext/118872219/HTMLSTART Full text (HTML)] | [http://www3.interscience.wiley.com/cgi-bin/fulltext/118872219/PDFSTART Full text (PDF)]{{dead link|date=February 2019|bot=medic}}{{cbignore|bot=medic}})</ref> and was often taken as constituting (by itself) the family Najadaceae.<ref>[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=10603 197. Najadaceae A. L. de Jussieu], ''[Flora of North America](/source/Flora_of_North_America)''</ref>

The [APG II system](/source/APG_II_system), of 2003 (unchanged from the [APG system](/source/APG_system), of 1998), places the genus in family [Hydrocharitaceae](/source/Hydrocharitaceae), in the order [Alismatales](/source/Alismatales) of the [monocots](/source/Monocotyledon).<ref name="apg2003"/>

An infrageneric classification of two sections is proposed: Section ''Americanae'' and sect. ''Caulinia''.<ref name="Ito et al. 2017">Ito, Y., Nr. Tanaka, S.W. Gale, O. Yano, J. Li (2017) "Phylogeny of Najas (Hydrocharitaceae) revisited: Implications for systematics and evolution". ''Taxon'' '''66'''(2): 309-323. [https://doi.org/10.12705/662.2 doi: 10.12705/662.2]</ref>

;Species<ref name=wet/>
* ''[Najas affinis](/source/Najas_affinis)'' <small>Rendle</small> - South America, Senegal, Guinea-Bissau
* ''[Najas ancistrocarpa](/source/Najas_ancistrocarpa)'' <small>A.Braun ex Magnus</small> - China, Japan, Taiwan
* ''[Najas arguta](/source/Najas_arguta)'' <small>Kunth</small> - Cuba, Costa Rica, Panama, South America
* ''[Najas australis](/source/Najas_australis)'' <small>Bory ex Rendle</small> - India, Madagascar, Mauritius, KwaZulu-Natal, Seychelles
* ''[Najas baldwinii](/source/Najas_baldwinii)'' <small>Horn</small> - West Africa
* ''[Najas brevistyla](/source/Najas_brevistyla)'' <small>Rendle</small> - Assam
* ''[Najas browniana](/source/Najas_browniana)'' <small>Rendle</small> - southern China, India, Taiwan, Java, Cavern Island in Northern Territory of Australia
* ''[Najas chinensis](/source/Najas_chinensis)'' <small>N.Z.Wang</small> - Primorye, China, Taiwan, Japan
* ''[Najas conferta](/source/Najas_conferta)'' <small>(A.Braun) A.Braun</small> - Cuba, Hispaniola, Panama, Brazil
* ''[Najas faveolata](/source/Najas_faveolata)'' <small>A. Br. ex Magnus</small>
* ''[Najas filifolia](/source/Najas_filifolia)'' <small>R.R.Haynes</small> - southeastern United States (Georgia, Alabama, Florida)
* ''[Najas flexilis](/source/Najas_flexilis)'' <small>(Willd.) Rostk. & W.L.E. Schmidt</small> - temperate Northern Hemisphere
* ''[Najas gracillima](/source/Najas_gracillima)'' (A.Braun ex Engelm.) Magnus - Asia, North America
* ''[Najas graminea](/source/Najas_graminea)'' <small>Delile</small> - Africa, Asia, New Guinea, Melanesia, northern Australia; naturalized in California and parts of Europe
* ''[Najas grossareolata](/source/Najas_grossareolata)'' <small>L.Triest</small> - Sri Lanka
* ''[Najas guadalupensis](/source/Najas_guadalupensis)'' <small>(Spreng.) Magnus</small> - North and South America, Caribbean
* ''[Najas hagerupii](/source/Najas_hagerupii)'' <small>Horn</small> - Ghana, Mali
* ''[Najas halophila](/source/Najas_halophila)'' <small>L.Triest</small> - Java, New Guinea, Queensland
* ''[Najas heteromorpha](/source/Najas_heteromorpha)'' <small>Griff. ex Voigt</small> - eastern India
* ''[Najas horrida](/source/Najas_horrida)'' <small>A.Braun ex Magnus</small> - Africa, Madagascar, Sinai
* ''[Najas indica](/source/Najas_indica)'' <small>(Willd.) Cham.</small> - Indian Subcontinent, China, Southeast Asia, New Guinea
* ''[Najas kurziana](/source/Najas_kurziana)'' <small>Rendle</small> - Bihar, East Timor
* ''[Najas madagascariensis](/source/Najas_madagascariensis)'' <small>Rendle</small> - Madagascar; naturalized in Mauritius
* ''[Najas malesiana](/source/Najas_malesiana)'' <small>W.J.de Wilde</small> - India, Bangladesh, Indochina, Malaysia, Indonesia, Philippines; naturalized in eastern Brazil
* ''[Najas marina](/source/Najas_marina)'' <small>L.</small> - widespread and nearly cosmopolitan
* ''[Najas minor](/source/Najas_minor)'' <small>All.</small> - widespread in Europe, Asia, Africa; naturalized in eastern North America
* ''[Najas oguraensis](/source/Najas_oguraensis)'' <small>Miki</small> - East Asia, Himalayas (Pakistan, Nepal, northern India)
* ''[Najas pectinata](/source/Najas_pectinata)'' <small>(Parl.) Magnus</small> - Sahara
* ''[Najas pseudogracillima](/source/Najas_pseudogracillima)'' <small>L.Triest</small> - Hong Kong
* ''[Najas rigida](/source/Najas_rigida)'' <small>Griff.</small> - eastern India
* ''[Najas schweinfurthii](/source/Najas_schweinfurthii)'' <small>Magnus</small> - Senegal, Cameroon, Ethiopia, Sudan, Tanzania 
* ''[Najas tenuicaulis](/source/Najas_tenuicaulis)'' <small>Miki</small> - Honshu Island in Japan
* ''[Najas tenuifolia](/source/Najas_tenuifolia)'' <small>R.Br.</small> - Hong Kong, Southeast Asia, Australia
* ''[Najas tenuis](/source/Najas_tenuis)'' <small>Magnus</small> – India, Sri Lanka, Myanmar
* ''[Najas tenuissima](/source/Najas_tenuissima)'' <small>(A.Braun ex Magnus) Magnus</small> - Finland, Russia, Hokkaido
* ''[Najas testui](/source/Najas_testui)'' <small>Rendle</small> - western + central Africa
* ''[Najas welwitschii](/source/Najas_welwitschii)'' <small>Rendle</small> - tropical Africa, western India
* ''[Najas wrightiana](/source/Najas_wrightiana)'' <small>A.Braun</small> - Mexico, Central America, Cuba, Bahamas, Venezuela; naturalized in Florida

==References==
{{Reflist}}

==External links==
* [http://delta-intkey.com/angio/www/najadace.htm Najadaceae] {{Webarchive|url=https://web.archive.org/web/20090201131049/http://delta-intkey.com/angio/www/najadace.htm |date=2009-02-01 }} in L. Watson and M.J. Dallwitz (1992 onwards) [http://delta-intkey.com/angio/ ''The families of flowering plants''] {{Webarchive|url=https://web.archive.org/web/20070103200438/http://delta-intkey.com/angio/ |date=2007-01-03 }}: descriptions, illustrations, identification, information retrieval. Version: 9 March 2006. http://delta-intkey.com {{Webarchive|url=https://web.archive.org/web/20070103200438/http://delta-intkey.com/ |date=2007-01-03 }}.
* [http://www.alpine-plants-jp.com/art/itotorigemo_1.htm ''Najas japonica'' Nakai]- Flavon's art gallery
* [http://greif.uni-greifswald.de/floragreif/?fam=Najadaceae&gen=&spec=&flora_search=taxon Najadaceae of Mongolia in FloraGREIF]{{Dead link|date=July 2025 |bot=InternetArchiveBot |fix-attempted=yes }}

{{Najas Navbox}}
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Category:Najas
Category:Aquatic plants
Category:Hydrocharitaceae genera
Category:Botanical taxa named by Carl Linnaeus

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Adapted from the Wikipedia article [Najas](https://en.wikipedia.org/wiki/Najas) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Najas?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.