Lettuce (scientific name: Lactucasatival. Var。 Angustanairish。 ) Also called lettuce. Lettuce in Compositae is a biennial herb, which can form a variety of fleshy tender stems. Alias lettuce, lettuce, green shoots, lettuce. Date of birth:1-April. Lettuce originated from the Mediterranean coast and was introduced to China in the 5th century. The above-ground stems are edible, the skin is white and green, the meat is crisp and tender, the young stems are green, and they turn white and green after maturity. Young stems can be eaten raw, cold, fried, dried or pickled, and young leaves can also be eaten. The stems and leaves contain lettuce, including lettuce (C 1 1H 14O4 or C22H36O7). It tastes bitter and has analgesic effect. Lettuce has strong adaptability and can be cultivated in spring and autumn or winter, mainly in spring and harvested in summer.