What is "crithmum"

Crithmum is a genus of flowering plant with the sole species Crithmum maritimum, known as samphire, rock samphire, or sea fennel. Rock samphire is an edible wild plant. It is found on southern and western coasts of Britain and Ireland, on mediterranean and western coasts of Europe including the Canary Islands, North Africa and the Black Sea. " Samphire" is a name also used for several other unrelated species of coastal plant.