John Winthrop Jr brought packets of lettuce seed to America from England in the 1600s. Iceberg lettuce was called Crisphead until the 1920's. To keep the lettuce cool during shipping, huge quantities of ice were mounded on top of it, giving it the appearance of an iceberg. Iceberg lettuce will last up to two weeks if stored properly. The United States ranks second in world lettuce production.
China is ranked number one.
As a general rule, the greener the leafy green, the more nutritional value. Southern Greens Prepackaged salads are growing in popularity throughout the United States. They are not, however catching on as quickly in the Southeast as they are in the rest of the country. One reason for this is the popularity of traditional southern greens like kale, collard greens, mustard greens and turnip greens. All of these leafy greens are rich in Vitamins A, C and beta cerotene, while collards and kale are considered to be two of the most nutritious foods grown in the United States.