View source for Luronium

{{short description|Species of plant}}
{{Speciesbox
|image = LuroniumNatans2.jpg
|status = LC
|status_system = IUCN3.1
|status_ref =
|genus = Luronium
|parent_authority = [[Constantine Samuel Rafinesque-Schmaltz|Raf.]]
|species = natans
|authority = ([[Carl Linnaeus|L.]]) [[Constantine Samuel Rafinesque-Schmaltz|Raf.]]
|synonyms =
*''Alisma natans'' <small>L.</small>
*''Elisma natans'' <small> (L.) Buchenau</small>
*''Echinodorus natans'' <small>(L.) Engelm. in P.F.A.Ascherson</small>
*''Nectalisma natans'' <small>(L.) Fourr.</small>
*''Alisma diversifolium'' <small>Gilib.</small>
*''Alisma natans ''var''. sparganiifolium'' <small>Fr.</small>
}}
'''''Luronium natans''''' is a species of [[aquatic plant]] commonly known as the '''floating water-plantain'''. It is the only recognized species in the genus '''''Luronium''''', native to western and central Europe, from Spain to Britain to Norway east to Ukraine.<ref name="Kew"/><ref name="ginalollabrigida"/>
==Description==
Stems elongated, rising in the water or creeping and rooting at the nodes. Submerged [[leaves]] (if present) basal, linear, floating or aerial leaves elliptical to ovate. [[Flowers]] hermaphrodite, long-pedunculate in the axils of the floating or aerial leaves. [[Stamens]] 6. [[Carpels]] 6–15 in an irregular whorl, free, each with 1 ovule; styles apical. Fruitlets achenial, longitudinally many-ribbed, with a short apical beak. 2''n''&nbsp;=&nbsp;42.<ref name="ginalollabrigida"/><ref name="Bio"/><ref name="JNCC"/><ref name="Natural"/>
[[File:Luronium natans stoloniferous.jpg|thumb|left|Floating water plantain ''Luronium natans'' showing stoloniferous habit]]
[[File:Luronium ladders.jpg|thumb|left|Characteristic 'ladder' venation pattern of submerged leaves.]]
''Luronium natans'' can be a difficult plant to identify.<ref name=BSBI/> It is both very variable and resembles many other aquatic plants with strap-like leaves such as bur-reeds (''Sparganium''), young water-plantain plants (''Alisma''), arrowheads (''Sagittaria''), lesser water-plantain (''Baldellia'')<ref name=Romero/> and mudwort (''Limosella aquatica'').<ref name=Lansdown/><ref name=Kay/> The stoloniferous habit is an important distinguishing feature, and the unusual shape of the floating leaves, which are rounded at the tips and tend to taper gradually into the stem, is also helpful. However, floating leaves are not always present, especially in lake populations.<ref name=Lansdown/> Submerged leaves have a characteristic ladder pattern with whitish flecks when seen underwater.<ref>{{cite web |last1=Jones |first1=R.A. |title=Plant Crib: Luronium natans |url=https://bsbi.org/wp-content/uploads/dlm_uploads/Luronium_Crib.pdf}}</ref><ref name=Willby/>
[[File:Luronium white flecks.jpg|thumb|Floating water-plantain showing whitish flecks on leaves visible underwater. Llyn Hir, Ceredigion, Wales, UK.]]
==Distribution==
The range of floating water-plantain is uncertain. It is widely distributed in western and central Europe, with confirmed records from Belgium, Denmark, France, Germany, the Netherlands, Poland, Republic of Ireland and the United Kingdom.<ref name=Lansdown/><ref name=IUCN/> It is also present but rare in northern Spain,<ref name=Romero/> the Czech Republic,<ref name=Rybk/> Norway and Sweden.<ref name=Lansdown/><ref name=IUCN/>
Further east the distribution is much more uncertain and requires verification. Records from Bulgaria, Italy, Bosnia-Herzegovina, Croatia, Hungary, Lithuania, Macedonia, Montenegro, Romania,<ref name=Anca/> Russia, Serbia, Slovakia, Slovenia, Austria, the Transcarpathian region of Ukraine and Transylvania either are doubtful or are unconfirmed.<ref name=IUCN/>
==Ecology==
Floating water-plantain grows predominantly in base-poor lakes, ponds and slow-flowing rivers with low to moderate nutrient levels,<ref name=Willby/><ref name=Roelofs/> although in some cases it appears able to tolerate alkaline systems and / or high nutrient levels.<ref name=Lansdown/><ref name=Greulich/> It has proved able to colonise certain man-made freshwater systems, especially canals.<ref name=Kay/><ref name=Willby/>
[[File:Llyn Dinas - geograph.org.uk - 1175897.jpg|thumb|Llyn Dinas, a low nutrient base-poor shallow lake on the edge of Snowdonia National Park supports a strong population of ''Luronium natans'']]
===Lakes===
Lake populations predominantly occur on silty or peaty substrates,<ref name=Szank/> growing at depths up to at least 3.5 m.<ref name=Goldsmith/> In deeper water it reproduces vegetatively by stolons or production of [[cleistogamy|cleistogamous]] seed. This often results in populations with low genetic diversity.<ref name=Cox/> Shallow water populations produce short-lived flowers which may cross-pollinate.<ref name=Kay/>
Floating water-plantain favours a certain amount of disturbance to survive, as it is a poor competitor.<ref name=Szank/><ref name=Lansdown/><ref name=Greul2/> In Llyn Egnant and Llyn Teifi (Wales, UK), which are used as reservoirs for public water supply, floating water-plantain probably benefits from the resulting increase in water level fluctuation, suppressing competition from other aquatic plants and promoting flowering. However, in sites where water level fluctuations are larger in amplitude, ''L. natans'' is absent. Lake populations of this plant are strongly associated with soft-water conditions and low nutrient concentrations.<ref name=Roelofs/><ref name=BSBI/>
===Rivers===
In Britain, floating water-plantain is rare in river habitats. River populations in general occur in slow-flowing, low-gradient sections of base-poor rivers along with aquatic plants such as intermediate water-starwort ''Callitriche hamulata'', bog pondweed ''Potamogeton polygonifolius'' and shoreweed ''Littorella uniflora''. These populations are small and usually associated with upstream lakes that may act as sources of propagules.<ref name=Lansdown/> Riverine populations in France and Denmark are associated with natural river-floodplain systems where new oxbow lakes are constantly being created by erosion and deposition.<ref name=Barrat/><ref name=Greul2/>
[[File:Luronium natans in a river.jpg|thumb|Floating water-plantain (''Luronium natans''), Afon Gwyrfai a Llyn Cwellyn Special Area of Conservation, Snowdonia, Wales, UK.]]
===Ponds===
The ecology of floating water-plantain in ponds is not well understood, but generally it seems to require broadly low nutrient, soft water situations with some disturbance, such as lowland heathland pools subject to grazing by livestock.<ref name=FHT/>
===Artificial habitats===
In the past, floating water-plantain has proved successful at exploiting certain types of artificial habitats, notably the British canal system<ref name=Kay/><ref name=Willby/> and the Dombes traditional fishpond system in France.<ref name=Wezel/> Both these systems have in common a moderate level of disturbance which helps to suppress competing species that might otherwise exclude it.<ref name =Lansdown/>
[[File:Montgomery_Canal_at_Arddlin_-_geograph.org.uk_-_580121.jpg|thumb|The Montgomery Canal in Britain has been widely colonized by floating water-plantain and is now a protected area for it. Regular desilting and cutting is required to restrict competition from more vigorous plants.]]
==Conservation, threats and restoration==
Within Europe, floating water-plantain is listed under Annexes II and IV of the Habitats Directive and Appendix I of the Bern Convention. Within Britain it is on Schedule 4 of the Conservation (Natural Habitats, etc.) Regulations 1994; Schedule 8 of the Wildlife and Countryside Act, 1981, and on the IUCN Red List it is classified as 'Least Concern'(LC).<ref name='Arkive' />
Floating water-plantain seems quite tolerant of acidification, as evidenced by its relative abundance in several Welsh lakes that have suffered severe declines in pH due to acid rain, and also seems able to tolerate moderate water level fluctuation as is seen when certain lakes were converted to reservoirs. Losses have mainly been associated with nutrient enrichment (eutrophication), such as in the Shropshire-Cheshire meres.<ref>{{cite book |last1=Lockton |first1=Alex | last2=Whild |first2=Sarah |title=The Flora and Vegetation of Shropshire |date=2015 |url=https://archive.org/details/flora-and-vegetation-of-shropshire-2015}}</ref>
In the Netherlands, restoration of floating water-plantain and other threatened freshwater plants has been successfully achieved by removing the organic sediment layer and reducing inputs of calcium-rich surface water.<ref name=Roelofs/>
[[File:Luronium rosette.jpg|thumb|Terrestrial rosette of Luronium natans at Brown Moss in Shropshire in 2003]]
==Cultural==
In 2009 it featured on a first class [[Royal Mail]] stamp in the series "[[List of British postage stamps#2009|Endangered Plants]]".<ref name="Plantnetwork"/>It is said to have "spread eastwards from its core natural habitats in the lakes of Snowdonia and mid Wales in the 19th century, taking advantage of the canal network. In recent decades, however, pollution and recreational boating have led to its disappearance from many lowland waterways".<ref name="Arkive"/>
==References==
{{Reflist|3|refs=
<ref name=Anca>[https://www.researchgate.net/profile/Adrian_Oprea2/publication/41907733_PLANTS_FROM_THE_HABITAT_DIRECTIVE_-_ANNEX_IIb_PRESENTS_IN_ROMANIA/links/54b788710cf24eb34f6eb13b/PLANTS-FROM-THE-HABITAT-DIRECTIVE-ANNEX-IIb-PRESENTS-IN-ROMANIA.pdf Anca S, Adrian O, Ion S. 2007. Plants from the Habitat Directive – AnnexIIb, Present in Romania. Buletinul Grădinii Botanice Iaşi 14.]</ref>
<ref name="Bio">[https://www.biodiversitylibrary.org/page/5875553#page/65/mode/1up Rafinesque, Constantine Samuel. 1840. Autikon Botanikon 63].</ref>
<ref name=BSBI>[https://web.archive.org/web/20140228094051/http://sppaccounts.bsbi.org.uk/content/luronium-natans Lockton, A.J. 2014. Species account: ''Luronium natans''. Botanical Society of the British Isles]</ref>
<ref name=Cox>Cox K, Leyssen A, Mergeay J, Ronse A, Packet J, Denys L. Genetic assessment of ''Luronium natans'' in lower Belgium: analysis of population connectivity of an aquatic perennial. INBO.R.2014.5021339. 2014. Brussel, Instituut voor Natuur- en Bosonderzoek (INBO).</ref>
<ref name=Willby>[https://www.apms.org/wp-content/uploads/japm-31-01-070.pdf Willby, N.J. and Eaton, J.W. 1993. The Distribution, Ecology and Conservation of ''Luronium natans'' (L.) Raf. in Britain. Journal of Aquatic Plant Management 31:70-76]</ref>
<ref name=Goldsmith>Goldsmith B, Shilland E, Shilland J, Turner S. 2014. Floating water-plantain ''Luronium natans'' (L.) Raf.: current distribution and status in Llyn Padarn and Llyn Cwellyn, Wales. NRW Evidence Report No. 73. Natural Resources Wales, Bangor.</ref>
<ref name="ginalollabrigida">{{Cite web|url=http://luirig.altervista.org/flora/taxa/index1.php?scientific-name=luronium+natans|title=Luronium natans [Mestolaccia natante]|website=luirig.altervista.org|language=it|access-date=2017-01-30}}</ref>
<ref name=Greulich>{{cite journal|last1=Greulich|first1=Sabine|last2=Bornette|first2=Gudrun|last3=Amoros|first3=Claude|last4=Roelofs|first4=Jan G.M.|title=Investigation on the fundamental niche of a rare species: an experiment on establishment of Luronium natans|journal=Aquatic Botany|volume=66|issue=3|year=2000|pages=209–224|issn=0304-3770|doi=10.1016/S0304-3770(99)00073-X|bibcode=2000AqBot..66..209G }}</ref>
<ref name=Greul2>{{cite journal|last1=Greulich|first1=Sabine|last2=Bornette|first2=Gudrun|last3=Amoros|first3=Claude|title=Persistence of a rare aquatic species along gradients of disturbance and sediment richness|journal=Journal of Vegetation Science|volume=11|issue=3|year=2000|pages=415–424|issn=1100-9233|doi=10.2307/3236634|jstor=3236634 |bibcode=2000JVegS..11..415G }}</ref>
<ref name=IUCN>[http://www.iucnredlist.org/details/162134/0 Lansdown, R.V. 2011. ''Luronium natans''. The IUCN Red List of Threatened Species 2011: e.T162134A5547543.Downloaded on 21 June 2017.]</ref>
<ref name="JNCC">{{Cite web|url=http://jncc.defra.gov.uk/ProtectedSites/SACselection/species.asp?FeatureIntCode=S1831|title=1831 Floating water-plantain Luronium natans - SAC selection species account|website=jncc.defra.gov.uk|language=en|access-date=2017-01-30}}</ref>
<ref name=Kay>{{cite journal |last1=Kay |first1=Q.O.N. |last2=John |first2=R.F. |last3=Jones|first3=R.A. |title=Biology, genetic variation and conservation of Luronium natans (L.) Raf. in Britain and Ireland |journal=Watsonia |date=1999 |page=301-315 |url=http://archive.bsbi.org.uk/Wats22p301.pdf}}</ref>
<ref name="Kew">{{Cite web|url=http://apps.kew.org/wcsp/namedetail.do?name_id=280518|title=World Checklist of Selected Plant Families: Royal Botanic Gardens, Kew|website=apps.kew.org|language=en-GB|access-date=2017-01-30}}</ref>
<ref name="Natural">[http://naturalhistory.museumwales.ac.uk/corespecies/CMS/Resources/pdfs/Luronium_natans/Luronium_natans.pdf ''Luronium natans'', National Museum of Wales]</ref>
<ref name=Lansdown>[http://publications.naturalengland.org.uk/file/111042 Lansdown RV & Wade PM (2003). Ecology of the Floating Water-plantain, ''Luronium natans''. Conserving Natura 2000 Rivers Ecology Series No. 9. English Nature, Peterborough.]</ref>
<ref name=FHT>[https://freshwaterhabitats.org.uk/dowrog-common-flagship-site/ Freshwater Habitats Trust: Dowrog Common Flagship Pond Site]</ref>
<ref name=Roelofs>Roelofs JGM. 1996. Restoration of eutrophied shallow softwater lakes based upon carbon and phosphorus limitation. Netherlands Journal of Aquatic Ecology, 30, 197-202.</ref>
<ref name=Romero>[https://www.researchgate.net/profile/Marco_Rubinos/publication/233617835_Luronium_natans_a_rare_species_in_the_Iberian_peninsula/links/0046352b7fbd3b9dbf000000.pdf Romero M, Rubinos M, Ramil P. 2004. ''Luronium natans'', a rare species in the Iberian peninsula. 137, 85-90]</ref>
<ref name=Rybk>[http://www.sagittaria.cz/upload/publikace/angl-natura-min.pdf Rybková R, Pohlová R. 2005. Plants of the Natura 2000 Network in the Czech Republic. Sagittaria: Association for Nature Conservation of Central Moravia and Prague Botanical Garden, Prague.]</ref>
<ref name=Wezel>[https://rdcu.be/dl7NR Wezel, A., Oertli, B., Rosset, V. et al. Biodiversity patterns of nutrient-rich fish ponds and implications for conservation. Limnology 15, 213–223 (2014). https://doi.org/10.1007/s10201-013-0419-7]</ref>
<ref name=Barrat>[https://www.sciencedirect.com/science/article/pii/S0304377097000910?casa_token=nyV8Zka6-lgAAAAA:lLwJ8u0zKj0LkTvNBn-JtnIrP17m_3zUaAahNt4Tbat8D82e8F9Zng0DwbhSvC0IkWeJ4_zTCA Barrat-Segretain, M-H., Bornette G., Hering-Vilas-Boas A. 1998. Comparative abilities of vegetative regeneration among aquatic plants growing in disturbed habitats. Aquatic Botany 60, 201-211.]</ref>
<ref name=Szank>{{cite journal|last1=Szańkowski|first1=Marcin|last2=Kłosowski|first2=Stanisław|journal=Hydrobiologia|title=Habitat conditions of the phytocoenoses dominated by Luronium natans (L.) Rafin in Poland|volume=455|issue=1/3|year=2001|pages=213–222|issn=0018-8158|doi=10.1023/A:1011914607379|s2cid=26133228 }}</ref>
<ref name="Plantnetwork">{{cite web |url=https://plantnetwork.org/news/endangered-species-stamps/ |title=Endangered Species Stamps |author=<!--Not stated--> |date= July 2009|website=PlantNetwork |publisher= |access-date= }}</ref>
<ref name="Arkive">{{Cite web|url=http://www.arkive.org/floating-water-plantain/luronium-natans|title=Floating water-plantain videos, photos and facts - Luronium natans|website=ARKive|language=en-GB|access-date=2017-01-30|archive-url=https://web.archive.org/web/20170421125523/http://www.arkive.org/floating-water-plantain/luronium-natans/|archive-date=2017-04-21|url-status=dead}}</ref>
}}
==External links==
*[http://www.iucnredlist.org/details/162134/0 IUCN Red List of Threatened Species]
*[http://www.tela-botanica.org/bdtfx-nn-40217-synthese Tela Botanica, Alisma nageante]
*[http://inpn.mnhn.fr/espece/cd_nom/106807 Inventaire Nationale du Patrimonie Naturel]
*[http://www.umwelt.sachsen.de/umwelt/natur/18207.htm Umwelt Sachsen, Schwimmendes Froschkraut (''Luronium natans'')]
{{Taxonbar|from=Q1470418}}
[[Category:Alismataceae]]
[[Category:Alismataceae genera]]
[[Category:Monotypic Alismatales genera]]
[[Category:Aquatic plants]]
[[Category:Flora of Europe]]
[[Category:Taxa named by Constantine Samuel Rafinesque]]
[[Category:Habitats Directive species]]