Lettuce varieties are an important part of many diets, and there are several types available. The three-letter variety COS is a cos lettuce, which is a type of butterhead lettuce with a mild flavor. BIBB is a four-letter variety, which is a type of Bibb lettuce, a buttery and sweet variety. ICEBERG is a seven-letter variety, which is a crunchy and mild variety. ROMAINE is also a seven-letter variety, which is a crisp and flavorful variety. Finally, REDLEAF is a seven-letter variety, which is a mild and tender variety. All of these lettuce varieties can be used in salads, sandwiches, and other dishes.