Annual or biennial herbs, 25- 100 cm tall. The roots extend vertically. The stem is erect and solitary, with panicle branches on the upper part, and all the stems and branches are white. Basal leaves and lower stems and leaves are large, undivided, oblanceolate, elliptic or oblanceolate, 6-15cm long and1.5-6.5cm wide.
Achene is oblanceolate, 4 mm long, 65438 0.3 mm wide, flat, light brown, with 6-7 veinlets on both sides, and the tip is sharp and filiform, about 4 mm long, almost as long as achene. The crown hair is 2 layers, slender and slightly rough.
Extended data
Lettuce is a cold-resistant vegetable, which likes cold climate and is not resistant to high temperature. The germination temperature is above 4℃, and 15-20℃ is the best. If the temperature exceeds 30℃, it will not germinate. Its seedlings can tolerate sub-zero low temperature, the suitable temperature for seedling growth is 15-20℃, and the growth temperature for stem is 1 1- 18℃. Lettuce likes a large temperature difference between day and night, so it needs a higher temperature for flowering and fruiting, and the optimum temperature is 19-22℃.
It is extremely sensitive to the state of soil surface water and needs continuous water supply to keep the soil moist. And is suitable for growing in clay loam or loam with rich organic matter and water and fertilizer conservation. Lettuce likes slightly acidic soil.
Lettuce is fragrant and refreshing, and the meat is tender. The stems can be eaten raw, cold, fried, dried or pickled into cans. This is a common vegetable.
This species is cultivated in the coastal areas of China and throughout China. It is a cold-resistant vegetable, which likes cold climate and is not resistant to high temperature. Like humidity. And is suitable for growing in clay loam or loam with rich organic matter and water and fertilizer conservation, and the propagation mode is sowing. Cultivated varieties include lettuce, lettuce and iceberg lettuce.
Edible, delicious and crisp, it is a popular vegetable. It can stimulate the secretion of digestive enzymes and stimulate appetite.
Baidu encyclopedia-lettuce