Mertensia maritima is a species of flowering plant in the borage family, and is known by the common names oyster leaf in North America, oyster plant in the British Isles, and sea bluebells.

It is a perennial herb producing a stem approaching 50 centimeters in maximum length.

[2] It is native to Britain and Northern Europe; however, populations in the British Isles are decreasing.

There are two other varieties that exist: This plant grows on sand or shingle beaches where the ground can be siliceous or calcareous, and contains humus from decaying seaweed.

[3] It mainly grows in a sub-Arctic climate and is exposed to very cold temperatures, waves that crash on the shore and strong winds.