In Disclosure No. 49 of VD about the "Submerged Lands of the Mediterranean" we exposed the colonization of the Mediterranean Sea bottom by terrestrial plants during the last glacial period. These plants subsequently adapted the salinity to flood their growing areas due to the rise of the water level by the thaw.

Thus oceanic Posidonia is currently an endemic plant of the Mediterranean seabed with anatomical characteristics similar to the terrestrial plants from which it comes. As can be seen in the photo a thick rippling stems (underground stems emitting more or less regular sections of roots and leaves), cintiforme leaves (ribbon form) that allow using sunlight (as a way of producing carbohydrates and oxygen) and Roots that are introduced into the seabed.

Between September and December according to the depth in which it lives produces flowers and fruits with seeds as well as terrestrial plants.