Lettuce (Lactuca sativa) is an annual plant of the Asteraceae family. The Asteraceae family contains the herbs arnica, burdock, boneset, calendula, chamomile, chicory, cronewort (mugwort), coltsfoot, dandelion, echinacea, elecampane, feverfew, gravel root, grindelia, liferoot, milk thistle, tansy, yarrow, valerian, wormwood, and wild lettuce. It also contains the foods sunflower seeds, lettuces, true artichokes, sun chokes (also known as Jerusalem artichokes), escarole, and endive. And it contains the decorative flowers asters, chrysanthemums, dahlias, bachelor’s buttons, daisies, cosmos, coneflowers, goldenrods, sunflowers, and zinnias.

Cultivated lettuce is closely related to the wild lettuce, L. scariola, from which it was undoubtedly derived. Wild lettuce is now widely scattered over the globe, but it originated in inner Asia Minor, the trans-Caucasus, Iran, and Turkistan.

According to Herodotus (484 BC-425 BC), lettuce was served on the tables of the Persian kings of the 6th century B.C. In the 5th and 4th centuries B.C., other great Greek writers described and praised its virtues. As in the development of the cabbages, the primitive forms of lettuce were loose, leafy, and sometimes “stemmy” types; the looseheading and firm-heading forms occurred much later.

Lettuce was first cultivated in ancient Egypt as early as 2680 BC, and was selectively bred by the Egyptians into a plant grown for its edible leaves. Lettuce was considered a sacred plant of the reproduction god Min, and it was carried during his festivals and placed near his images. The plant was thought to help the god “perform the sexual act untiringly.” Its use in religious ceremonies resulted in the creation of many images in tombs and wall paintings. The cultivated variety appears to have been about 30 inches tall and resembled a large version of the modern romaine lettuce. These upright lettuces were developed by the Egyptians and passed to the Greeks, who in turn shared them with the Romans. Lettuce was popular among the Romans about the beginning of the Christian Era, and had been brought to a fairly advanced state of culture and improvement. Around 50 AD, Roman agriculturalist Columella described several lettuce varieties – some of which may have been ancestors of today’s lettuces.

Common garden lettuce (L. sativa) was known in China in the 5th century, if not earlier. In China, lettuce represents good luck. It is served on birthdays, New Year’s Day and other special occasions.

Lettuce appears in many medieval writings, especially as a medicinal herb. Hildegard of Bingen mentioned it in her writings on medicinal herbs between 1098 and 1179, and many early herbals also describe its uses. Christopher Columbus introduced varieties of lettuce to North America during his second voyage in 1493. Its culture was reported on Isabela Island (now called Crooked Island) in the Bahamas in 1494. The oak-leaved and curled-leaf types, and various colors now known, were all described in the 16th and 17th centuries in Europe. It was common in Haiti in 1565. In 1586, Joachim Camerarius provided descriptions of the three basic modern lettuces – head lettuce, loose-leaf lettuce and romaine or cos lettuce. When it was introduced into South America is not known , but it was probably soon after the discovery. It was under cultivation in Brazil before 1650. Lettuce was first planted in California, the lettuce capital of the United States, by the Spanish missionaries in the 17th century. Lettuce was among the first garden seeds sown in every European colony in North America. Between the late 16th century and the early 18th century, many varieties were developed in Europe, particularly in Holland. Books published in the mid-18th and early 19th centuries describe several varieties found in gardens today.

Because its short life span after harvest, lettuce was originally sold relatively close to where it was grown. The early twentieth century saw the development of new packing, storage, and shipping technologies that improved the lifespan and transportability of lettuce and resulted in a significant increase in availability. During the 1950s, lettuce production was revolutionized with the development of vacuum cooling, which allowed field cooling and packing of lettuce, replacing the previously used method of ice-cooling in packing houses outside the fields.

Lettuce is very easy to grow, and as such has been a significant source of sales for many seed companies. Tracing the history of many varieties is complicated by the practice of many companies, particularly in the US, of changing a variety’s name from year to year. This was done for several reasons, the most prominent being to boost sales by promoting a “new” variety or to prevent customers from knowing that the variety had been developed by a competing seed company. Documentation from the late 19th century shows between 65 and 140 distinct varieties of lettuce, depending on the amount of variation allowed between types – a distinct difference from the 1,100 named lettuce varieties on the market at the time. Names also often changed significantly from country to country.

Lettuce leaves are one of the very low-calorie green vegetables. One hundred grams of fresh greens provide just 15 calories, but they contain many phytochemicals that have health-promoting and disease-prevention properties. Just 100 g of fresh, raw lettuce provides 247% of daily vitamin A, and 4443 µg of beta-carotene. These compounds have antioxidant properties. Lettuce is a rich source of vitamin K. Fresh lettuce contains good amounts folate and vitamin C. Zea-xanthin (1730 µg per 100 g), an important dietary carotenoid in lettuce, is selectively absorbed into the retinal macula lutea, where it thought to provide antioxidant and filter UV rays falling on the retina. Diets rich in xanthin and carotenes are thought to offer some protection against age-related macular disease (ARMD) in the elderly. Lettuce also contains good amounts of minerals like manganese, phosphorus, iron, calcium, copper, magnesium, and potassium, which are essential for metabolism. Lettuce is rich in B-complex group of vitamins like thiamine, vitamin B6, and riboflavin.

Regular inclusion of lettuce in salads is known to prevent osteoporosis, iron-deficiency anemia and believed to protect from cardiovascular diseases, ARMD, Alzheimer’s disease and cancers.

100 grams of raw leaf lettuce contains:

In the store, choose leaf lettuce whose leaves are crispy and bright in color. Avoid sunken leaves with spots or discoloration. Regardless of the type, all lettuces should feature crispy, fresh leaves that are free of dark or slimy spots.

Leaf lettuces should be washed, and any excess water removed before storing in the refrigerator. Pack leaf lettuce in a bag or store in the refrigerator. Leaf lettuce will stay fresh for up to two to three days.

Remove any outer discolored leaves. Then trim off their bitter tips. Chop the remaining leaf to a desired size and discard the bottom stem or root portion. Wash leaves then in clean running water and soak in salt water for about half an hour in order to remove sand and any parasite eggs and worms. Pat dry or use a salad spinner to remove the excess water.

Raw, fresh lettuce is commonly used in salads, burgers, spring rolls, and sandwiches.