Eryngium maritimum aka Eryngo

Eryngium maritimum, or sea holly, belongs to the Apiaceae family. This perennial grows along European coasts and around the Mediterranean. Its native range extends east to the western Caucasus. It is native to Britain and Ireland. In the wild, it grows on sand dunes and shingle shores. Its deep, wide root system helps hold shore sand in place.

The plant forms a bushy clump with stiff, spiny leaves. Their waxy surface has a blue-green hue and white veins. Some leaves remain through winter, giving it a semi-evergreen habit. Plants stand about 2 feet [0.6 metres] tall. The RHS gives a garden height range of 1.6–3.3 feet [0.5–1 metre]. Clumps spread up to 1.6 feet [0.5 metres] across. They take two to five years to reach full size.

Blue flowers form rounded umbels, each framed by pointed, spiny bracts. These leaf-like bracts make a collar around each flowerhead. The RHS lists flowering from April to September. The blue flowers and pale-veined leaves suit gravel and coastal gardens. The plant also fits cottage gardens and informal beds. The RHS includes it among choices for wildlife gardens. Its coastal origin makes it a useful subject for shore planting.

Grow sea holly in full sun and sandy soil. Good drainage matters, and neutral or alkaline soil suits it. It grows in both exposed and sheltered sites. The RHS records drought resistance and rates its hardiness H5. Plants For A Future lists USDA zones 4–8. Sow seed in autumn to raise new plants. The RHS says the plant needs no pruning. Slugs, snails, and leaf and bud eelworms may cause damage. Root rot and powdery mildew are possible diseases.

Plants For A Future lists leaves, roots, and shoots as edible. Young shoots can be blanched by keeping light from them. They are then cooked and used in place of asparagus. Roots can be cooked as a vegetable or made into sweets. The source describes a mild sweetness and a carrot-like scent. It also records past herbal use of the roots. Candied roots once served as restorative lozenges in England. These records describe traditional use, not proof of medical benefit. Plants For A Future reports no known hazards for this species.