Lettuce is a member of the sunflower family and includes the following varieties: iceberg, romaine, looseleaf (green or red), and butterhead. Iceberg lettuce got its name in the 1920s when California started transporting the lettuce under large mounds of ice to keep it cool and fresh. Other names you may have heard are "crisphead" or "head-lettuce" because its leaves grow in tightly packed heads.
The Romans named romaine lettuce. They loved lettuce because they believed it had healthful properties. In fact, Ceasar Augustus erected a statue in honor of lettuce because he believed it cured him from an illness.
Lettuce is handpicked from fields when it is mature and is then shipped directly to its destination. When shopping for lettuce, look for healthy, darker green outer leaves. Iceberg lettuce should be symmetrical in shape, compact, and firm. Very hard heads aren't as sweet, though, so avoid them. Store the lettuce in a plastic bag in the refrigerator crisper drawer. Iceberg lettuce lasts for 2 weeks in the refrigerator, romaine lasts for 10 days, and butterhead lettuce lasts for about 1 week. When ready to use the lettuce, rinse the leaves in cold water or soak them in a cold water bath, swishing the water around with your hand. Dry the leaves on a paper towel or in a salad spinner, if you have one. Remember the darker the leaves are the more nutrients they contain. Thus, the outer darker leaves are more nutrient-dense than the inner lighter leaves.