What name is Cos lettuce more commonly known by in America?

People in British-speaking areas of Europe know the leafy green which many others call romaine, as cos (or cos lettuce), because it supposedly originated on the Greek island of Cos (now called Kos), off the coast of Turkey.

Originating in western Europe and the eastern Mediterranean area, Cos, (or romaine) has been cultivated and eaten (cooked or raw) for almost 5,000 years and may very well be the oldest form of cultivated lettuce. Egyptian tombs reveal paintings of lettuce with long, pointed leaves, resembling romaine.

The earliest known name for the plant in English is “Roman lettuce” (from around the 17th century). The Romans were big fans of the plant; they ate it cooked, and believed it had healing properties. According to Pliny, the emperor Augustus Caesar even erected a statue in honor of the salad ingredient after it helped him recover from an illness. The English “romaine” comes to us via the French “laitue romaine," literally meaning "Roman lettuce."

Today it is the second most popular form of lettuce, after iceberg. Romaine is an excellent source of vitamin C, (it has 5 times more than iceberg lettuce), and is the most nutritious member of the lettuce family. Generally speaking, the darker the green, the more vitamins and minerals (beta-carotene, calcium and iron, etc.) a head of lettuce contains.