Althenia

{{Short description|Genus of aquatic plants}} {{Automatic taxobox |image = Althenia_filiformis_Andalucia,_Spain_01_Apr._2011.jpg |image_caption = ''Althenia filiformis'' |taxon = Althenia |authority = Petit |subdivision_ranks = Species |subdivision = See text |synonyms = '''''Lepilaena''''' <small>J.Drumm. ex W.H.Harvey<ref>Hooker's J. Bot. Kew Gard. Misc. 7: 57. 1855 IPNI</ref></small> |synonyms_ref = }} thumb|right|Lepilaena australis Harv., 1855 '''''Althenia''''' is a genus of aquatic plants of the family Potamogetonaceae.<ref>{{Cite web |url=http://www.ars-grin.gov/cgi-bin/npgs/html/genus.pl?465 |title=United States Department of Agriculture database |access-date=2008-04-08 |archive-url=https://web.archive.org/web/20110605135113/http://www.ars-grin.gov/cgi-bin/npgs/html/genus.pl?465 |archive-date=2011-06-05 |url-status=dead }}</ref> This has long been a group of two species in the Mediterranean Europe and South Africa, but in 2016 was revised to include an Australasian relative, '''''Lepilaena'''''.<ref>Ito, Y., Nr. Tanaka, P. García-Murillo, A.M. Muasya (2016) [http://authors.elsevier.com/a/1SehA3m3nMlXJG A new delimitation of the Afro-Eurasian plant genus ''Althenia'' to include its Australasian relative, ''Lepilaena'' (Potamogetonaceae) – evidence from DNA and morphological data]. ''Molecular Phylogenetics and Evolution'' '''98:''' 261-270.</ref> The genus is named after the agronomist Jean Althen.<ref>{{cite web |title=Genus Althenia |url=https://casabio.org/taxa/althenia |website=CasaBio |access-date=28 April 2024 |ref=casabio}}</ref>

== Description == This genus is made up of aquatic herbs. The bristle-like leaves are clustered at the nodes. The wider bases produce broad ligules.<ref name="SAGenera">{{Cite book |last=Phillips |first=Edwin Percy |title=The genera of South African flowering plants |publisher=Government Printer |year=1951 |publication-place=South Africa}}</ref>

The flowers are unisexual. The male flowers have a perianth made of three minute scales and have a single stamen.<ref name="SAGenera" />

The female flowers have a perianth made of one to three segments. The gynoecium has three carpels with a single pendulous ovule in each ovary. The filiform styles gradually pass into the carpels and the stigmas are large and oblique. The mature carpels are oblique and compressed with a winged or thickened margin. The seeds are pendulous, oblong and compressed. The embryo is straight.<ref name="SAGenera" /> ==Species== :* ''Althenia australis'' (aquatic) :* ''Althenia bilocularis'' (aquatic) :* ''Althenia cylindrocarpa'' (brackish water,<ref name ="FloraBase">{{FloraBase|name=''Lepilaena cylindrocarpa'' (Muell.Stuttg.)|id=120}}</ref> marine<ref name=Larkum />) :* ''Althenia filiformis'' :* ''Althenia hearnii'' :* ''Althenia marina'' (marine<ref name=Larkum />) :* ''Althenia orientalis'' :* ''Althenia patentifolia'' :* ''Althenia preissii'' (aquatic) :* ''Althenia tzvelevii''

==Lepilaena== '''''Lepilaena''''' was a genus of aquatic and marine flowering plant comprising 6 or more species endemic<ref name=Hammer>{{cite book|last=Hammer|first=Ulrich Theodore|title=Saline Lake Ecosystems of the World|date=1986|publisher=Springer London, Limited|isbn=978-90-6193-535-3}}</ref><ref name=Kubitzki>{{cite book|editor=Klaus Kubitzki|title=Flowering Plants. Monocotyledons: Alismatanae and Commelinanae (except Gramineae) (The Families and Genera of Vascular Plants) |page=472|date=1998|publisher=Springer|isbn=978-3-540-64061-5}}</ref> to coastal and brackish or alkaline inland waters of temperate Australia, Tasmania, and New Zealand.<ref name=Larkum>{{cite book|editor-last= Larkum |editor-first=Anthony W.D. |editor2-last=Duarte|editor2-first=Carlos|editor3-last=Orth|editor3-first= Robert J.|contribution = Taxonomy and biogeorgraphy of seagrasses| title = Seagrasses: Biology, Ecology and Conservation |publisher= Springer-Verlag New York, LLC|year=2005|isbn=978-1-4020-2942-4}}</ref><ref name=Hammer />

The species are appended with common names that derive from their description as water-mats; for example, ''L. australis'' is referred to as Austral water-mat and ''L. marina'' as Sea water-mat.

Interpretation of molecular evidence for this poorly studied genus suggests a close affinity with ''Zannichellia'', another genus of aquatic plants.<ref name=Larkum/> Two species are noted for their occurrence in marine environs, ''L. cylindrocarpa'' and ''L. marina'', in estuaries and tidal flats.<ref name=Larkum/> ''L. cylindrocarpa'' is also found in a variety of brackish inland waters of mainland Australia.<ref name ="FloraBase"/> Other species may be found in habitats of fresh to brackish, still or slowly moving, coastal or inland waters.

Based on the molecular and morphological evidence, all the species have been transferred to the genus '''''Althenia''''' in 2016.<ref>Ito, Y., Nr. Tanaka, P. García-Murillo, A.M. Muasya (2016) [http://authors.elsevier.com/a/1SehA3m3nMlXJG A new delimitation of the Afro-Eurasian plant genus ''Althenia'' to include its Australasian relative, ''Lepilaena'' (Potamogetonaceae) – evidence from DNA and morphological data]. ''Molecular Phylogenetics and Evolution'' '''98:''' 261-270.</ref>

==References== {{Reflist}}

==External links== *[https://florabase.dpaw.wa.gov.au/browse/profile/20926 Flora of Western Australia] *{{FloraBase|name=''Lepilaena'' Harv.}} *{{cite web|last=Guiry|first=M.D.|last2=Guiry|first2=G.M.|year=2008|title=Lepilaena|work=AlgaeBase|publisher=World-wide electronic publication, National University of Ireland, Galway|url=http://www.algaebase.org/search/genus/detail/?genus_id=44018|accessdate= 2009-02-21}}

Category:Aquatic plants Category:Potamogetonaceae Category:Alismatales genera