Lettuce is an annual plant belonging to the daisy family. It is grown mainly as a leafy vegetable used for salads. Half of the world's production of lettuce is now in China.

Lettuce was first cultivated by the ancient Egyptians. They first crushed the seeds to make oil, then began to use the leaves as well. The Romans named it lactuca, from which the English word lettuce comes. These early forms of lettuce were the tall kind we now call Romaine or cos lettuce. They can grow well in hot conditions before setting seed.

The round forms of lettuce such as Iceberg, were cultivated later. These are best grown in cool climates where the leaves form before the seeds develop.

Lettuce is a rich source of vitamin K and vitamin A.