There are three types of lettuce: knot ball lettuce, crumpled leaf lettuce, and upright lettuce.

Lettuce (Lactuca?sativa?L. var.?ramosa?Hort.? [1]?) Common name for leaf lettuce, also known as gooseberry, Mark's lettuce, lettuce, lettuce, belonging to the lettuce genus Asteraceae. It is an annual or biennial herbaceous crop with long obovate leaves, densely packed into kale-like leaf bulbs, which can be eaten raw, crisp and refreshing, and slightly sweet.

Growth habit:

Lettuce like cool environment, neither cold hardy, nor heat resistant, the growth of the appropriate temperature of 15 ℃ -20 ℃, the fertility period of 90-100 days. Seeds are more resistant to low temperatures, can germinate at 4 ℃. Germination temperature 18-22 ℃, higher than 30 ℃ almost no germination.

Plant growth period, like cool climate, 15-20 ℃ growth is optimal, high yield, excellent quality; sustained higher than 25 ℃, growth is poor, leaf quality coarse old, slightly bitter taste. But cold hardiness is also quite strong, 0 ℃ or even short-term sub-zero low temperature on the growth of no great obstacle.

Lettuce root system is developed, waxy leaf surface, drought tolerance is quite strong, but cultivated in fertile and moist soil, high yield, good quality.