This is a genus of plants from around the northern hemisphere, including herbaceous perennials, trailing plants from seashores, and alpines. The North American ones tend to be known as bluebells. The flowers are indeed blue, and come in compact head, although the flowers are hanging, not upright.

Mertensia maritima is a rare British native, unusual and charming. It is spreading, prostrate seaside perennial, commonly known as the oyster plant, as taste of its leaves resembles that of oysters. Delicate tubular blue flowers open from pink buds above the succulent blue-green leaves.