| 词条 | Posidonia oceanica |
| 释义 |
| image = Posidonia 2 Alberto Romeo.jpg | status = LC | status_system = IUCN3.1 | status_ref = [1] | genus = Posidonia | species = oceanica | authority = (L.) Delile | range_map = Posidonia_oceanica_range.PNG | range_map_caption = Posidonia oceanica range }}{{Expand Italian|date=July 2018}} Posidonia oceanica (commonly known as Neptune grass or Mediterranean tapeweed) is a seagrass species that is endemic to the Mediterranean Sea. It forms large underwater meadows that are an important part of the ecosystem. The fruit is free floating and known in Italy as "the olive of the sea" (l'oliva di mare[2]). Balls of fibrous material from its foliage, known as egagropili, wash up to nearby shorelines. DescriptionPosidonia oceanica is a flowering plant which lives in dense meadows or along channels in the sands of the Mediterranean. It is found at depths from {{convert|1|-|35|m|ft}}, according to water clarity. Subsurface rhizomes and roots stabilize the plant while erect rhizomes and leaves reduce silt accumulation. The leaves are ribbon-like, appearing in tufts of 6 or 7, and up to {{convert|1.5|m|ft}} long. Average leaf width is around {{convert|10|mm}}. The leaves are bright green, perhaps turning brown with age, and have 13 to 17 parallel veins. The leaf terminus is rounded or sometimes absent because of damage. Leaves are arranged in groups, with older leaves on the outside, longer and differing in form from the younger leaves they surround. The rhizome type stems are found in two forms: one growing up to {{convert|150|cm}} beneath the sand and the other rising above the sand. All stems are approximately {{convert|10|mm}} thick and upright in habit. This arrangement of the rhizomes eventually forms a mat; the surface contains the active parts of the plant, whereas the center is a dense network of roots and decomposing stems. The flowering plant's common name is Neptune grass.[3] In 2006 a huge clonal colony of P. oceanica was discovered south of the island of Ibiza. At {{convert|8|km}} across, and estimated at around 100,000 years old,[4] it may be one of the largest and oldest clonal colonies on Earth.[5][6][7] Range and habitatThis species is found only in the Mediterranean Sea where it is in decline, occupying an area of about 3% of the basin. This corresponds to a surface area of about {{convert|38000|km2}}. Posidonia grows best in clean waters, and its presence is a marker for lack of pollution.[8] The presence of Posidonia can be detected by the masses of decomposing leaves on beaches. Such plant material has been used for composting, but Italian laws prohibit the use of marine algae and plants for this purpose.[9] TaxonomyThe genus Posidonia is named after Poseidon, the Greek god of the seas, while oceanica refers to its former wide distribution. Carl Linnaeus gave the first botanical description of this species in Systema Naturae, although the genus was then named Zostera. The APG system (1998) and APG II system (2003) accept the genus as constituting the sole genus in the family Posidoniaceae, which it places in the order Alismatales, in the clade monocots. The Angiosperm Phylogeny Website concludes that the three families Cymodoceaceae, Posidoniaceae and Ruppiaceae form a monophyletic group.[10] Earlier systems classified this genus in the family Potamogetonaceae or in the family Posidoniaceae but belonging to order Zosterales. Secondary metabolitesTo date 51 natural products have been reported from P. oceanica, including natural phenols, phenylmethane derivatives, phenylethane derivatives, phenylpropane derivatives and their esters, chalkones, flavonols, 5-alpha-cholestanes, and cholest-5-enes. Many of the compounds reported for P. oceanica were, however, not detected by appropriate phytochemical methods and some most probably represent artifacts and are not genuine natural products of P. oceanica.[11] See also
References1. ^Pergent, G., Semroud, R., Djellouli, A., Langar, H. & Duarte, C. 2010. Posidonia oceanica. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. 2. ^{{cite web|url=http://www.tuteladelblu.it/home/2002/pdf2002/NEWS_16_08_02_PISCIOTTA.pdf|title=Posidonia oceanica|language=Italian|quote=Dopo essere fecondato, in estate fa crescere e maturare il suo frutto, l’oliva di mare (si chiama così perché ha una forma arrotondata).}} 3. ^{{cite web|url=http://www.divesitedirectory.co.uk/seagrass_meadows.html|title= Posidonia oceanis}} 4. ^{{cite web|url=http://www.theportugalnews.com/cgi-bin/article.pl?id=1152-20|title= Portuguese scientists discover world's oldest living organism}} 5. ^{{cite web|url= http://www.ibiza-spotlight.com/news/2006/monster_plant_280506_i.htm|title= Ibiza's Monster Marine Plant|accessdate= 2007-05-09|author= Ibiza Spotlight|date= 28 May 2006|deadurl= yes|archiveurl= https://web.archive.org/web/20060827123801/http://www.ibiza-spotlight.com/news/2006/monster_plant_280506_i.htm|archivedate= 27 August 2006|df= dmy-all}} 6. ^{{cite web|last=Pearlman |first=Jonathan |url=https://www.telegraph.co.uk/science/9066393/Ancient-seagrass-Oldest-living-thing-on-earth-discovered-in-Mediterranean-Sea.html |title='Oldest living thing on earth' discovered |publisher=The Telegraph |date=7 February 2012 |accessdate=11 February 2012}} 7. ^{{cite journal|last=Arnaud-Haond|first=Sophie|author2=Duarte, Carlos M. |author3=Diaz-Almela, Elena |author4=Marbà, Núria |author5=Sintes, Tomas |author6=Serrão, Ester A. |author7=Bruun, Hans Henrik |title=Implications of Extreme Life Span in Clonal Organisms: Millenary Clones in Meadows of the Threatened Seagrass Posidonia oceanica|url=http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030454|journal=PLoS ONE|volume=7|issue=2|pages=e30454|doi=10.1371/journal.pone.0030454|pmid=22312426|pmc=3270012}} 8. ^{{cite journal | doi = 10.1016/S0141-1136(97)00023-8 | volume=45 | title=Posidonia oceanica: a biological indicator of past and present mercury contamination in the mediterranean sea | journal=Marine Environmental Research | pages=101–111}} 9. ^http://www.tirsavplus.eu/documenti/normativa/D_lgs_75_2010%20normativa_fertilizzanti.pdf 10. ^{{cite web|url=http://www.mobot.org/MOBOT/Research/APweb/orders/alismatalesweb.htm#Alismatales |title=Alismatales |publisher=Mobot.org |accessdate=11 February 2012}} 11. ^{{cite journal |date=October 2010 |author1=Heglmeier, A |author2=Zidorn, C | title = Secondary metabolites of Posidonia oceanica | volume = 38 | issue = 5 | pages = 964–70 | issn = 0305-1978 | journal = Biochemical Systematics and Ecology |location = Amsterdam | doi = 10.1016/j.bse.2010.07.001 }} External links{{Commons-inline}}
3 : Posidonia|Biota of the Adriatic Sea|Biota of the Mediterranean Sea |
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