Mertensia maritima aka Northern Shorewort

Mertensia maritima is a low perennial in the Boraginaceae family. Its common names include oysterplant, oysterleaf, and sea lungwort. It grows across northern parts of Asia, Europe, and North America. Its native range includes Britain and Ireland. Kew records its range from subarctic lands to the northeastern United States. In the wild, it grows on shingle beside the sea. Plants For A Future describes it as uncommon and declining.

The plant spreads along the ground rather than growing upright. It reaches about 0.3 feet [0.1 metres] in height. Garden plants spread 0.3–1.6 feet [0.1–0.5 metres] across. They take two to five years to reach full size. The fleshy leaves have a blue-grey cast with green tones. Each leaf can reach 0.3 feet [0.1 metres] long. The plant sheds its leaves rather than keeping them year-round. Pink buds open into bright blue flowers in early summer. These bell-shaped blooms form clusters on branching stems.

Give oysterplant gritty, sandy soil that drains very freely. It suits lean soil rather than rich ground. It accepts acid, neutral, or alkaline conditions. Choose a sheltered spot with sun and some shade at midday. The RHS also lists partial shade as suitable. Established plants resist drought and tolerate dry to moist soil. Young plants need shade and must not dry out. The RHS rates its hardiness H5, covering lows near 5°F [−15°C]. Chicago Botanic Garden lists USDA zones 4–5.

Its low form suits gravel gardens and coastal planting schemes. The RHS also suggests containers, patios, and informal cottage gardens. Its blue foliage and flowers provide interest close to ground level. Sow seed in pots in an autumn cold frame. Divide plants with care when spring growth starts. Cut plants back once flowering ends. Slugs and snails may damage them, but the RHS reports few disease problems. Plants For A Future does not flag it as weedy.

Plants For A Future lists leaves, flowers, and roots as edible. Leaves can be eaten raw or cooked, and flowers raw. The leaves have a thick texture that becomes slippery when chewed. Some accounts compare their taste to oysters, though others find them bland. The same source records root use by Inuit people in Alaska. It reports no known hazards, but this does not establish safety for pets. It lists no known medicinal uses or other non-food uses.