Lettuce by John Spottiswood.

These are mild salad greens that are always served fresh, either in salads or as garnishes. There are four basic categories: iceberg lettuce, with leaves that grow in a dense "head," leaf lettuce, with loosely gathered leaves, butterhead lettuce, with tender leaves that form a soft head, and romaine lettuce, with closely packed leaves in an elongated head. Select lettuce that has rich color and crisp, fresh-looking leaves.