Along with crisphead lettuce, butterhead is one of the two main types of head lettuce. This vegetable is a small head lettuce with leaves that grow close to and surrounding the head of the vegetable. The leaves may be light green to dark green or a reddish purple color. Small loose-headed greens with tender soft leaves provide a sweet flavor for salads and sandwiches. It is also known as bibb, Boston or limestone lettuce.