Iceberg Lettuce :
The most popular type of lettuce, iceberg lettuce is very heat-sensitive. Iceberg lettuce is a variety of lettuce with crisp leaves which grows in a spherical head resembling a cabbage. The leaves on the outside tend to be green and the leaves in the center go from pale yellow to nearly whitish as you move closer and closer to the center of the head with the sweetest leaves in the center of the head. It can be eaten raw or can be cooked.