Lactuca sativa, is by far the most popular of the leafy salad vegetables. The lettuce belongs to the very large family Compositae, which includes cultivated species such as chicory and endive, and various wild plants with edible leaves, all more or less tough and bitter, e.g. the dandelion and some thistles. The original wild lettuce, L. serriola, is still common in Europe and temperate Asia, and is as harsh as any of these. It is also called ‘prickly’ or ‘wood’ lettuce, an unpromising plant for cultivation.