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What is
Posidonia
oceanica?

Posidonia oceanica is an aquatic plant endemic to the Mediterranean sea

forming extensive meadows,

known as underwater forests,

capable of sheltering high biodiversity

of species and its role in the ecosystem

is of great importance.

BENEFICIOS_Posidonia, Posidonia, Posidonia Oceanica, Valencia 2030

Fertilization cycle of the Posidonia oceanica

Posidonia oceanica settles on new spaces through sexual reproduction and vegetative reproduction, the latter predominating over the former. Each reproductive strategy is described in detail below.

Posidonia inflorescences

Posidonia fertilization

Posidonia fruit

Posidonia seed

Flowering occurs in late autumn.

In a few days the inflorescences develop. They are located in the center of the leaf bundle and consist of a long peduncle on which spikelets with several flowers (1 to 5) are carried. Some flowers are hermaphroditic and others (usually the tallest) are only male, due to early abortion of the gynoecium.

Each hermaphrodite flower has a single ovule that will be fertilized by the pollen released from the anthers (visible in the image above) of the flowers. The filamentous and viscous pollen will successfully travel through the water to other flowers.

Once the pollen fertilizes the ovule, it thickens until it forms a ripe fruit. This process, which begins in autumn, will last about 4 months. Posidonia fruit is small, oval and dark in color, similar to olives, which is why it is known as sea olive.

In spring the already ripe fruit is released from the plant and floats adrift for a few days. Thus the seeds are dispersed far, following the currents. After hours or days they split, releasing a single seed that falls to the seabed, where it germinates and gives rise to a new plant.