Najas, the water-nymphs 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,Genera of Hydrocharitaceae, GRIN Taxonomy for PlantsAngiosperm 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: | | Full text (PDF)) and was often taken as constituting (by itself) the family Najadaceae.197. Najadaceae A. L. de Jussieu, Flora of North America
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.
An infrageneric classification of two sections is proposed: Section Americanae and sect. Caulinia.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. doi: 10.12705/662.2
Species Najas affinis Rendle - South America, Senegal, Guinea-Bissau Najas ancistrocarpa A.Braun ex Magnus - China, Japan, Taiwan Najas arguta Kunth - Cuba, Costa Rica, Panama, South America Najas australis Bory ex Rendle - India, Madagascar, Mauritius, KwaZulu-Natal, Seychelles Najas baldwinii Horn - West Africa Najas brevistyla Rendle - Assam Najas browniana Rendle - southern China, India, Taiwan, Java, Cavern Island in Northern Territory of Australia Najas chinensis N.Z.Wang - Primorye, China, Taiwan, Japan Najas conferta (A.Braun) A.Braun - Cuba, Hispaniola, Panama, Brazil Najas faveolata A. Br. ex Magnus Najas filifolia R.R.Haynes - southeastern United States (Georgia, Alabama, Florida) Najas flexilis (Willd.) Rostk. & W.L.E. Schmidt - temperate Northern Hemisphere Najas gracillima (A.Braun ex Engelm.) Magnus - Asia, North America Najas graminea Delile - Africa, Asia, New Guinea, Melanesia, northern Australia; naturalized in California and parts of Europe Najas grossareolata L.Triest - Sri Lanka Najas guadalupensis (Spreng.) Magnus - North and South America, Caribbean Najas hagerupii Horn - Ghana, Mali Najas halophila L.Triest - Java, New Guinea, Queensland Najas heteromorpha Griff. ex Voigt - eastern India Najas horrida A.Braun ex Magnus - Africa, Madagascar, Sinai Najas indica (Willd.) Cham. - Indian Subcontinent, China, Southeast Asia, New Guinea Najas kurziana Rendle - Bihar, East Timor Najas madagascariensis Rendle - Madagascar; naturalized in Mauritius Najas malesiana W.J.de Wilde - India, Bangladesh, Indochina, Malaysia, Indonesia, Philippines; naturalized in eastern Brazil Najas marina L. - widespread and nearly cosmopolitan Najas minor All. - widespread in Europe, Asia, Africa; naturalized in eastern North America Najas oguraensis Miki - East Asia, Himalayas (Pakistan, Nepal, northern India) Najas pectinata (Parl.) Magnus - Sahara Najas pseudogracillima L.Triest - Hong Kong Najas rigida Griff. - eastern India Najas schweinfurthii Magnus - Senegal, Cameroon, Ethiopia, Sudan, Tanzania Najas tenuicaulis Miki - Honshu Island in Japan Najas tenuifolia R.Br. - Hong Kong, Southeast Asia, Australia Najas tenuis Magnus – India, Sri Lanka, Myanmar Najas tenuissima (A.Braun ex Magnus) Magnus - Finland, Russia, Hokkaido Najas testui Rendle - western + central Africa Najas welwitschii Rendle - tropical Africa, western India Najas wrightiana A.Braun - Mexico, Central America, Cuba, Bahamas, Venezuela; naturalized in Florida
References
External links Najadaceae in L. Watson and M.J. Dallwitz (1992 onwards) The families of flowering plants : descriptions, illustrations, identification, information retrieval. Version: 9 March 2006. http://delta-intkey.com . Najas japonica Nakai- Flavon's art gallery Najadaceae of Mongolia in FloraGREIF