Lettuce was first farmed for cooking oil, not salad leaves
DNA from 445 kinds of lettuce points to domestication near the Caucasus, where early farmers wanted its seeds, pressed for oil. Egyptians grew it that way by about 2680 BC and linked it to the fertility god Min. The bitterness-free leaves that fill modern salad bowls evolved much later, around 500 BC in southern Europe.
Lettuce, Lactuca sativa, belongs to the sunflower family, and its closest wild relative is prickly lettuce, an aggressive weed of temperate zones. The Romans called it lactuca after lac, milk, for the white latex that oozes from cut stems. Romaine takes its name from lettuces grown in Roman papal gardens, while cos refers to the Greek island of Kos, a centre of lettuce farming in Byzantine times.
Egyptian lettuce, depicted in tombs and carried in Min's festivals, stood about 75 centimetres tall and resembled a giant romaine. Greeks passed it to Romans, and around 50 AD the agricultural writer Columella described several varieties. From Italy, where it became cos, lettuce moved north and was reshaped into butterhead types. It reached China around the fifth to seventh century CE, route unknown. In 1586 Joachim Camerarius described the three basic kinds still grown today: head, loose-leaf and romaine. Columbus carried it to the Americas.
Breeding delayed bolting, the flowering that turns leaves bitter and unsaleable, and reduced latex while enlarging heads. Heat triggers bolting quickly, so commercial lettuce is harvested well before maturity, typically 65 to 130 days after planting. Left alone, a plant sends up a flower stalk up to a metre tall with small yellow blossoms whose seeds drift on feathery parachutes. Between 1992 and 2005 more than 85 field trials tested genetically modified lettuce in Europe and the United States, but none is grown commercially.
Because lettuce wilts fast, it was once sold near where it grew. Better packing and shipping in the early 20th century widened its reach, and vacuum cooling in the 1950s allowed lettuce to be chilled and packed right in the field. Seed firms muddied its history by renaming varieties annually: late 19th-century records show perhaps 65 to 140 distinct types sold under some 1,100 names. In 2023 world output, counted with chicory, reached 28 million tonnes, with China growing 53 per cent.
Source: Lettuce
