Mertensia maritima is a perennial coastal herb in the borage family (Boraginaceae), notable for its thick, glaucous blue-green leaves and small blue bell-shaped flowers. The genus Mertensia was named in honor of the German botanist Franz Carl Mertens and the species epithet maritima comes from Latin, meaning “of the sea.” Mertensia maritima is native to the cold and temperate coastal regions of northern Europe, including the North Sea, Baltic Sea, and Arctic coasts, where it grows on shingle beaches, sand dunes, and rocky shorelines influenced by sea spray.

Commonly known as oyster plant or oysterleaf, it is famed for the fresh leaves’ distinct oyster-like flavor, which made it a prized seasonal wild food in northern coastal Europe. These leaves are most often consumed raw in salads or as garnishes, sometimes lightly dressed, to preserve their delicate oyster-like aroma and flavor. In contemporary gastronomy, they are used to simulate seafood notes in plant-based dishes and as a luxury foraged ingredient in Nordic and Northern European cuisines.

Like many members of the borage family, M. maritima may also contain trace pyrrolizidine alkaloids, which are potentially hepatotoxic if consumed in large or chronic amounts, though levels in this species are generally considered low when eaten occasionally.