There is only one species or type of lettuce. Its scientific name is Lactuca sativa. It grows best in mild weather. High heat can kept lettuce from growing to this full size and can make the leaves taste bitter.
Lettuce became more readily available in the mid-twentieth century with the development of iceberg, which is typically topping on hamburgers, tacos, and other fast food; it is also the base for salads served in fast food chains. It has little nutritional value, with exception of some fiber.
The lettuce requirement had shifted from the iceberg type grown in the open field to the romaine and leafy lettuces that needed greenhouse or rain shelters for production.
The technology of rain shelter gives high harvest recovery at lower costs, and yields a highly differentiated product in terms of product safety because less agrochemical inputs are used.
Lettuce: Ingredient in salad for fast food meals
