Production cycle of lettuce: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.
Extended data:
nutritive value
Lettuce is rich in nutrients, especially leaves. Every 500g of fresh lettuce leaves (Beijing area) contains protein 10g, fat 2.5g, carbohydrate16.5g, calcium190mg, phosphorus185mg, iron 5.5mg and carotene10.
But the content in the stem is much lower. Every 500g of lettuce stem contains only 1.5g of protein, only 0.2g of fat, only 4.7g of carbohydrate, and very little carotene and vitamin C..
Children eat more lettuce, which is very beneficial to growth and development. Eating 200 grams of lettuce leaves every day can meet the needs of carotene, eating 500 grams of lettuce leaves can meet the needs of vitamin C, and it is also rich in phosphorus and calcium, which is very beneficial to promote the normal development of bones, prevent rickets and help normal teething.
Baidu encyclopedia-lettuce