Lettuce is an annual plant of the family Asteraceae. It is most often grown as a leaf vegetable, but sometimes for its stem and seeds. 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. One variety, celtuce, is grown for its stems, which are eaten either raw or cooked. In addition to its main use as a leafy green, it has also gathered religious and medicinal significance over centuries of human consumption. 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. As of 2021, world production of lettuce and chicory was 27 million tonnes, 53 percent of which came from China.
Lactuca, commonly known as lettuce, is a genus of flowering plants in the family Asteraceae. The genus includes at least 50 species, distributed worldwide, but mainly in temperate Eurasia.
Lactuca serriola, also called prickly lettuce, milk thistle, compass plant, and scarole, is an annual or biennial plant in the tribe Cichorieae within the family Asteraceae. It has a slightly fetid odor and is commonly considered a weed of orchards, roadsides and field crops. It is the closest wild relative of cultivated lettuce.
Boltonia asteroides, the white doll's daisy, false chamomile, or false aster, is a species of plant native to the United States and Canada. It is found primarily in the Mississippi Valley and Great Plains from Saskatchewan south to Texas and Florida, with isolated populations in the eastern United States. Reports of the species in New England, New York, and the Pacific Northwest appear to be introductions.
Lactuca biennis is a North American species of wild lettuce known by the common names tall blue lettuce and blue wood lettuce. It is widespread across much of the United States and Canada from Alaska and Yukon south as far as California, New Mexico, and Georgia.
Lactuca canadensis is a species of wild lettuce known by the common names Canada lettuce, Canada wild lettuce, and tall lettuce. Its true native range is not clear, but it is considered to be a native of the eastern and central parts of North America. It naturalized in the western part of the continent as well as in Eurasia.
Artemisia ludoviciana is a North American species of flowering plant in the daisy family Asteraceae, known by several common names, including silver wormwood, western mugwort, Louisiana wormwood, white sagebrush, lobed cud-weed, prairie sage, and gray sagewort.
Cirsium discolor, the field thistle, is a North American species of plants in the tribe Cardueae within the family Asteraceae. It is native to thirty-three states in the United States as well four Canadian provinces. It occurs across much of eastern and central Canada as well as eastern and central United States. It has been found from New Brunswick west to Saskatchewan and south as far as Texas and Georgia.
Pulicaria dysenterica, the common fleabane, or, in North America, meadow false fleabane, is a species of fleabane in the family Asteraceae. It is native to Europe and western Asia where it grows in a variety of habitats ranging from semi-arid Mediterranean woodlands to wetter situations. Pulicaria dysenterica is perennial and can form dense clusters of plants, spreading by its roots. It flowers at its maximum height of about 60 centimetres (2.0 ft). Leaves are alternately arranged and clasp the stem, which itself contains a salty-astringent liquid. The yellow inflorescences are typically composed of a prominent centre of 40–100 disc florets surrounded by 20–30 narrow, pistillate ray florets. When setting seed the flower heads reflex.
Helenium flexuosum is a North American plant species in the daisy family known by the common name purple sneezeweed. It is widespread across much of eastern and central United States and Canada, from Nova Scotia west to Ontario, Minnesota, and Kansas, south to Florida, Louisiana, and eastern Texas.
Doellingeria infirma, the cornel-leaf whitetop or cornel-leaved aster, is a perennial forb native to the eastern United States, that produces white composite flowers in late summer.
Helianthus decapetalus, known by the common names thinleaf sunflower and thin-leaved sunflower, is a perennial forb in the family Asteraceae. It is native to the Eastern and Central United States and Canada, from New Brunswick west to Iowa, Wisconsin, and Ontario, south as far as Georgia and Louisiana. It produces yellow composite flowers in late summer or early fall.
Sagittaria graminea, the grassy arrowhead or grass-leaved arrowhead, is an aquatic plant species native to eastern North America.
Bradburia pilosa, the soft goldenaster, is a North American species of flowering plants in the family Asteraceae, native to the south-central United States, primarily the southeastern Great Plains and lower Mississippi Valley, in the states of Texas, Oklahoma, Kansas, Missouri, Arkansas, Louisiana, Tennessee, Mississippi, and Alabama. Additional populations are reported farther east but these appear to be introductions. Its habitats include disturbed roadsides and pine-oak-juniper woods.
Cirsium texanum is a species of plants in the tribe Cardueae within the family Asteraceae found in North America. Common names include Texas thistle, Texas purple thistle or southern thistle. The species is native to northern Mexico and the southern Great Plains of the south-central United States. It grows in prairies and roadsides.
Erigeron flagellaris is a North American species of flowering plants in the family Asteraceae known by the common names trailing fleabane.
Erigeron grandiflorus is a North American species of flowering plant in the family Asteraceae known by the common names Rocky Mountain alpine fleabane and largeflower fleabane.
Lactuca floridana, commonly known as woodland lettuce, Florida lettuce, or false lettuce is a North American species of wild lettuce. It is native across much of central Canada and the eastern and central United States.
Lactuca graminifolia, the grassleaf lettuce is a North American species of wild lettuce. It grows in Mexico, Central America, Hispaniola, and the southern United States from Arizona to Florida, Virginia and the Carolinas.
Lactuca hirsuta, the hairy lettuce, is a North American species of wild lettuce. It is widespread across much of central Canada and the eastern and central United States from Ontario, Québec, Prince Edward Island, and Nova Scotia south as far as Texas, Louisiana, and Florida.
