Posidonia

Mediterranean seagrass ( Posidonia oceanica )

Posidonia ( Posidonia ), also known as Neptune plants are the only plant genus of the family of seagrass plants ( Posidoniaceae ) in the order of the plantain -like ( Alismatales ) within the monocot plants. It is one of the genera whose species, such as many species of the order frog spoon-shaped, are called with a similar habit and habitat, " seaweed ". They thrive in shallow temperate to subtropical areas of the Mediterranean Sea and west to the south of Australia.

  • 4.1 Notes and references

Description

Habit and foliage leaves

Posidonia species grow as grass -like perennial, herbaceous plants. These marine, submersed aquatic plants are anchored to the seabed with monopodial rhizomes. All plant parts are smooth.

The alternate and distichous arranged leaves are divided into leaf sheath and blade and have no petiole. The leaf sheath is open. The simple and flat to round stalk leaf blade has a nerve or several parallel nerves without lateral nerves. The leaf margins are smooth or serrated. There are no stomata present. In the axils of scales are available.

Inflorescences and flowers

There are leafless Blütenstandsschäfte available. The differently constructed inflorescences are composed of spike- like, few-flowered partial inflorescences and have no bracts.

The tiny, hermaphrodite flowers are reduced. There is no bloom. It is a circle with three free, fertile stamens present; since no filaments are formed, they have seated dust bag. The thread-like pollen grains have no aperture and are discharged into the sea. In each flower only a constant upper carpel is present. Each carpel contains only a continuous, orthotropic ovule. It is not formed a stylus, so the irregularly lobed stigma sits directly on the ovary. Pollination is in the water.

Fruit and seeds

They are buoyant, more or less fleshy follicles by air chambers in the pericarp. The seeds contain a straight embryo and no endosperm. When the fruit wall dissolves, the seeds will sink to the ocean floor and starts to germinate instantly.

Ingredients and chromosomes

There are proanthocyanidins present. The chromosome number is n = 10

Ecology

Posidonia species as the other seagrass species, the basis for their own ecosystems.

Systematics and distribution

The genus Posidonia was first described in 1806 by Charles Dietrich Eberhard König. The family name Posidoniaceae was published in 1895 by Sydney Howard Vines; often other publications are cited, for example, by John Hutchinson in Fam Fl. II, monocot. , 1934, 41 or ( Kunth ) Lotsy. Within the order of the Alismatales Posidoniaceae are closest related to the Ruppiaceae and Cymodoceaceae.

In the genus Posidonia ( Posidonia ), there are nine species. Only Posidonia oceanica occurs in the Mediterranean, all other types are west to south of Australia spread. The Australian species were divided into two groups.

  • In the Mediterranean, and on the southwest Atlantic coast of Europe endemic: Posidonia oceanica (L.) Delile
  • In the sea to the south and west of Australia before coming: Posidonia australis group: Posidonia angustifolia Cambridge & Kuo
  • Posidonia australis Hook. f
  • Posidonia sinuosa Cambridge and Kuo
  • Posidonia coriacea Cambridge and Kuo
  • Posidonia denhartogii Kuo and Cambridge
  • Posidonia kirkmanii Kuo and Cambridge
  • Posidonia ostenfeldii den Hartog
  • Posidonia robertsonae Kuo and Cambridge

Posidonia Posidonia coriacea robert soniae and may not be genetically different, so only a single article

All eight Australian Posidonia species occur before Western Australia. Posidonia angustifolia, Posidonia coriacea, Posidonia Posidonia sinuosa denhartogii and are also found off South Australia and Posidonia australis has the widest distribution in New South Wales, South Australia, Western Australia, Victoria and Tasmania.

Swell

  • The Posidoniaceae in APWebsite family. ( Section systematics and description)
  • The Posidoniaceae at DELTA by L. Watson & MJ Dallwitz family. ( Description section )
  • Youhao Guo, Robert R. Haynes, C. Barre Hellquist: Posidoniaceae. In: Wu Zheng -yi, Peter H. Raven, Deyuan Hong (eds.): Flora of China. Volume 23: Acoraceae through Cyperaceae, Science Press / Missouri Botanical Garden Press, Beijing / St. Louis 2010, ISBN 978-1-930723-99-3, pp. 117, online, PDF file (Section Description, systematics and distribution ).
  • Mike van Keulen: The genus Posidonia König ( nom. cons. ) ( Posidoniaceae ). Murdoch University, online ( section systematics and description).
  • Leslie Watson: Posidoniaceae. In: Western Australian Herbarium (ed.): Flora Base. The Western Australian Flora. Department of Environment and Conservation 2008, online.
  • C. den Hartog, John Kuo: Posidoniaceae. In: AWD Larkum, Robert Joseph Orth, Carlos M. Duarte: seagrasses: Biology, Ecology, and Conservation. Springer, Dordrecht, 2006 ISBN 1 - 402-02942 -X, pp. 10-11, limited preview in Google Book Search ( section systematics and description).
Perennial plant Cereal germ John Hutchinson (botanist)
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