There are also a few varieties with yellow, gold or blue-teal leaves. The leaves are colorful, mainly in the green and red color spectrums, with some variegated varieties. Plants generally have a height and spread of 15 to 30 cm (6 to 12 in). Lettuce's native range spreads from the Mediterranean to Siberia, although it has been transported to almost all areas of the world. Description Lettuce flowers Mature lettuce inflorescence in fruit The name romaine came from the variety of lettuce grown in the Roman papal gardens, while cos, another term for romaine lettuce, came from the earliest European seeds of the type from the Greek island of Kos, a center of lettuce farming in the Byzantine period. The current word lettuce, originally from Middle English, came from the Old French letues or laitues, which derived from the Roman name. The name Lactuca has become the genus name, while sativa (meaning 'sown' or 'cultivated') was added to create the species name. The Romans referred to lettuce as lactuca ( lac meaning 'dairy' in Latin), an allusion to the white substance, latex, exuded by cut stems. Lettuce is closely related to several Lactuca species from southwest Asia the closest relationship is to L. serriola, an aggressive weed common in temperate and subtropical zones in much of the world. L. sativa also has many identified taxonomic groups, subspecies and varieties, which delineate the various cultivar groups of domesticated lettuce. L. scariola is itself a synonym for L. serriola, the common wild or prickly lettuce. Synonyms for L. sativa include Lactuca scariola var.

The species was first described in 1753 by Carl Linnaeus in the second volume of his Species Plantarum. Lactuca sativa is a member of the Lactuca (lettuce) genus and the Asteraceae ( sunflower or aster) family. Contaminated lettuce is often a source of bacterial, viral, and parasitic outbreaks in humans, including E. Lettuce is a rich source of vitamin K and vitamin A, and a moderate source of folate and iron. Although this trait can be a problem to home gardeners who attempt to save seeds, biologists have used it to broaden the gene pool of cultivated lettuce varieties. sativa crosses easily within the species and with some other species within the genus Lactuca. It can be plagued by numerous nutrient deficiencies, as well as insect and mammal pests, and fungal and bacterial diseases. Generally grown as a hardy annual, lettuce is easily cultivated, although it requires relatively low temperatures to prevent it from flowering quickly. The 16th through 18th centuries saw the development of many varieties in Europe, and by the mid-18th century, cultivars were described that can still be found in modern gardens. By 50 AD, many types were described, and lettuce appeared often in medieval writings, including several herbals. Lettuce spread to the Greeks and Romans the latter gave it the name lactuca, from which the English lettuce is derived. Lettuce was originally farmed by the ancient Egyptians, who transformed it from a plant whose seeds were used to obtain oil into an important food crop raised for its succulent leaves and oil-rich seeds. As of 2021, world production of lettuce and chicory was 27 million tonnes, 53 percent of which came from China. Europe and North America originally dominated the market for lettuce, but by the late 20th century the consumption of lettuce had spread throughout the world. In addition to its main use as a leafy green, it has also gathered religious and medicinal significance over centuries of human consumption. One variety, celtuce (asparagus lettuce), is grown for its stems, which are eaten either raw or cooked. Lettuce is most often used for salads, although it is also seen in other kinds of food, such as soups, sandwiches and wraps it can also be grilled. It is most often grown as a leaf vegetable, but sometimes for its stem and seeds.

Lettuce ( Lactuca sativa) is an annual plant of the family Asteraceae.

Head iceberg lettuce