{{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. |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 of aquatic plants. It is cosmopolitan in distribution, first described for modern science by Linnaeus in 1753. Until 1997, it was rarely placed in the 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''</ref>
The APG II system, of 2003 (unchanged from the APG system, of 1998), places the genus in family Hydrocharitaceae, in the order Alismatales of the monocots.<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'' <small>Rendle</small> - South America, Senegal, Guinea-Bissau * ''Najas ancistrocarpa'' <small>A.Braun ex Magnus</small> - China, Japan, Taiwan * ''Najas arguta'' <small>Kunth</small> - Cuba, Costa Rica, Panama, South America * ''Najas australis'' <small>Bory ex Rendle</small> - India, Madagascar, Mauritius, KwaZulu-Natal, Seychelles * ''Najas baldwinii'' <small>Horn</small> - West Africa * ''Najas brevistyla'' <small>Rendle</small> - Assam * ''Najas browniana'' <small>Rendle</small> - southern China, India, Taiwan, Java, Cavern Island in Northern Territory of Australia * ''Najas chinensis'' <small>N.Z.Wang</small> - Primorye, China, Taiwan, Japan * ''Najas conferta'' <small>(A.Braun) A.Braun</small> - Cuba, Hispaniola, Panama, Brazil * ''Najas faveolata'' <small>A. Br. ex Magnus</small> * ''Najas filifolia'' <small>R.R.Haynes</small> - southeastern United States (Georgia, Alabama, Florida) * ''Najas flexilis'' <small>(Willd.) Rostk. & W.L.E. Schmidt</small> - temperate Northern Hemisphere * ''Najas gracillima'' (A.Braun ex Engelm.) Magnus - Asia, North America * ''Najas graminea'' <small>Delile</small> - Africa, Asia, New Guinea, Melanesia, northern Australia; naturalized in California and parts of Europe * ''Najas grossareolata'' <small>L.Triest</small> - Sri Lanka * ''Najas guadalupensis'' <small>(Spreng.) Magnus</small> - North and South America, Caribbean * ''Najas hagerupii'' <small>Horn</small> - Ghana, Mali * ''Najas halophila'' <small>L.Triest</small> - Java, New Guinea, Queensland * ''Najas heteromorpha'' <small>Griff. ex Voigt</small> - eastern India * ''Najas horrida'' <small>A.Braun ex Magnus</small> - Africa, Madagascar, Sinai * ''Najas indica'' <small>(Willd.) Cham.</small> - Indian Subcontinent, China, Southeast Asia, New Guinea * ''Najas kurziana'' <small>Rendle</small> - Bihar, East Timor * ''Najas madagascariensis'' <small>Rendle</small> - Madagascar; naturalized in Mauritius * ''Najas malesiana'' <small>W.J.de Wilde</small> - India, Bangladesh, Indochina, Malaysia, Indonesia, Philippines; naturalized in eastern Brazil * ''Najas marina'' <small>L.</small> - widespread and nearly cosmopolitan * ''Najas minor'' <small>All.</small> - widespread in Europe, Asia, Africa; naturalized in eastern North America * ''Najas oguraensis'' <small>Miki</small> - East Asia, Himalayas (Pakistan, Nepal, northern India) * ''Najas pectinata'' <small>(Parl.) Magnus</small> - Sahara * ''Najas pseudogracillima'' <small>L.Triest</small> - Hong Kong * ''Najas rigida'' <small>Griff.</small> - eastern India * ''Najas schweinfurthii'' <small>Magnus</small> - Senegal, Cameroon, Ethiopia, Sudan, Tanzania * ''Najas tenuicaulis'' <small>Miki</small> - Honshu Island in Japan * ''Najas tenuifolia'' <small>R.Br.</small> - Hong Kong, Southeast Asia, Australia * ''Najas tenuis'' <small>Magnus</small> – India, Sri Lanka, Myanmar * ''Najas tenuissima'' <small>(A.Braun ex Magnus) Magnus</small> - Finland, Russia, Hokkaido * ''Najas testui'' <small>Rendle</small> - western + central Africa * ''Najas welwitschii'' <small>Rendle</small> - tropical Africa, western India * ''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 }}
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Category:Najas Category:Aquatic plants Category:Hydrocharitaceae genera Category:Botanical taxa named by Carl Linnaeus