Mobile and fixed dune systems shape the dune landscape, forming a space of great biological and geological significance.
The sandy substratum and high salinity that create difficult life conditions make this dune space be associated with a specific type of flora called psammophilous flora, consisting of species arranged in bands in accordance with the progressive reduction of the wind and salt action.
These communities are formed by endemic plant species or of reduced distribution, even with unique populations in the Basque Autonomous Region. This is the case of the Medicago marina and Galium arenarium, endemic species of the Basque coasts and Aquitaine; and of the Alyssum loiseleurii, endemic of the coasts of the Cantabrian Sea and southwestern France.
The rocky coast that stretches between the Iñurritza and Oria Estuaries including the Mollarri shore, also keeps an associated flora adapted to the hard conditions resulting from being exposed to the swell.
Besides, small marsh areas have survived until present times, due to the mouth of Iñurritza, despite the urban and agricultural pressure. Here, we encounter flora species that result strange in the environment of the Basque Country. This is the case of the Salicornia dolichostachya, common in saline areas.