Posidoniaceae

The Posidoniaceae (scientific name Posidoniaceae) are a family of marine plants spread throughout the Mediterranean Sea and on the southern coast of Australia. The family is recognized by modern classification systems such as the 2009 APG III classification system and the APWeb (2001 onwards). It belongs to the order Alismatales and has a single genus, Posidonia, with 9 species. Together with some related families they form what is known as "seagrasses". This family is recognized by its monopodial rhizome and its branched racemose inflorescences.

Description

Theoretical Introduction in Descriptive Terminology of Plants

Perennial, rhizomatous, aquatic, submerged, marine herbs. They have the appearance of grasses (they are "sea grasses").

Leaves ribbon-shaped, distichous.

Hermaphroditic flowers, achlamyd, with 3 stamens and a single-carpellate gynoecium.

Spiciform cymose inflorescences, provided with foliose bracts.

The fruit is a berry.

Ecology

Distributed in the Mediterranean Sea and on the southern coast of Australia. The only species endemic to the Mediterranean is Posidonia oceanica.

In May 2006, an 8-kilometer-long specimen of this species was found in the vicinity of Formentera, Balearic Islands, which is the largest known plant, and the largest living being without considering fungi; its growth rate is 2 centimeters per year and its age has been estimated at 100,000 years.

Taxonomy

Theoretical Introduction in Taxonomy

See also Filogenia

The family was recognized by the APG III (2009), the Linear APG III (2009) assigned it the family number 40. The family had already been recognized by the APG II (2003).

The family has a single genus, Posidonia, with 9 species.

Etymology

The name posidonia derives from Poseidon (Ποσειδώνιος), the Greek god of the oceans and the waters.

This species is in danger because of the Caulerpa Taxifolia because it is poisonous and rots.