linguistic:paraphrasing, information:extraction
Taxonomy and etymology

Lactuca sativa is a member of the Lactuca (lettuce) genus and the Asteraceae (sunflower or aster) family. The species was first described in 1753 by Carl Linnaeus in the second volume of his Species Plantarum. Synonyms for L. sativa include Lactuca scariola var. sativa, L. scariola var. integrata and L. scariola var. integrifolia. L. scariola is itself a synonym for L. serriola, the common wild or prickly lettuce. L. sativa also has many identified taxonomic groups, subspecies and varieties, which delineate the various cultivar groups of domesticated lettuce. 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.

The Romans referred to lettuce as lactuca (lac meaning "dairy" in Latin), an allusion to the white substance, latex, exuded by cut stems. The name Lactuca has become the genus name, while sativa (meaning "sown" or "cultivated") was added to create the species name. The current word lettuce, originally from Middle English, came from the Old French letues or laitues, which derived from the Roman name. 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.