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Lettuce, Lactuca sativa

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lettuce

Lettuce is one of the most common and recognizable vegetables. And, surprisingly, one we under-use. 

Lettuce is Lactuca sativa, an annual plant in the daisy family (Asteraceae). Since we eat the leaves before it flowers, we rarely notice the small yellow flowers or the seed heads with whitish wind-carried seeds. The name lettuce is derived from Old French, from the Roman name for the plant, lactuca. Lactuca is based on the Latin word for milk, lac, and refers to the plant’s white sap. The white sap is another character of lettuce we rarely notice because it is more intense in flowering plants than in the early leaves we eat. Lactuca was also chosen as the scientific name for lettuce, so both names go back to the same root. The species epithet, sativa, means edible. 

lettuce flowers

Cultivation History

The closest wild relative of cultivated lettuce is prickly lettuce, Lactuca serriola, native to the Mediterranean region. However, differences from prickly lettuce suggest cultivated lettuce is derived from a species no longer found in the wild, although semi-wild forms grow in Egypt. Cultivated lettuce has bigger seeds, is slower to flower, less spiny, and less bitter than its wild relatives. 

People have been eating lettuce for millennia. Archaeological records of cultivation go back more than 6,500 years. Lettuce leaves were drawn on the walls of 12th Dynasty Egyptian tombs (about 2000 BCE), though they may have been grown for the edible oil in the seeds not the leaves. The Greeks and Romans cultivated and ate lettuce, starting the long process of shaping the varieties we have today.

The Romans took the plant to northern Europe. It reached China by the 5th century. Lettuce came to the New World with the first settlers. Twelve species of Lactuca now grow in North America, of which nine are native. 

The spiny, white-sapped plant of the Egyptians has been transformed into hundreds of varieties of lettuce, recognized as six major types: crisphead, butterhead, romaine (cos), leaf, latin and stem. The varieties vary in whether they form a head and what shape it is, in color, in texture, in crispness. Lettuce is the number one vegetable commercially grown around the world. Virtually every country grows it.

How to Prepare

Almost all that lettuce is eaten raw. A few varieties, especially the Asian stem lettuces (also called asparagus lettuces) are usually cooked. Yet historically, the European varieties of lettuce were served cooked as well as raw. Giacomo Castelvetro, writing of Italian vegetables to a British audience in 1611, gave this recipe for lettuce: “Cut the solid heart into four parts, each well oiled and salted and peppered, and roast them on a grid over hot charcoal (not burning embers) and eat them sprinkled with orange juice. They are delicious, almost as good as asparagus.” (Castelvetro p. 77)

Intrigued, I tried cooking the lettuce I had in the house. A very ordinary bit of old iceberg lettuce became a whole different taste and texture experience when sautéd. I liked it very much.

Benefits and Uses

Sources often say lettuce has a few vitamins but is rich in fiber. But other sources say it is an excellent source of vitamins A, B, E, and K, and iron. Given the hundreds of varieties, both could easily be true. 

From Egyptian times, lettuce has been used as a medicine. The milky sap contains compounds that are mild sedatives and not addictive, so that people took preparations of lettuce to relax or dull pain. This is probably the source of lettuce’s reputation for calming sexual desire, a story that made it widely used by celibate religious orders. At the same time, though, it was considered good for fertility, preventing miscarriages and aiding nursing mothers. It was certainly considered calming. A dish of lightly cooked lettuce was a traditional bedtime snack to induce sleep.

The milky sap contains a mixture of potentially biologically active compounds, but very little is produced in the leaves of commercial lettuce. Other lettuce relatives are the source of lactucarium, “lettuce opium.” A mid-twentieth century experiment found no effect at all of the compounds in lettuce but broad claims are made for lactucarium today. More studies are needed before we should conclude that all the historical uses of lettuce as a medicine are simply folklore. 

Lettuce is a major vegetable that dominates our salads worldwide today. It can be eaten cooked as well as raw and has a colorful history as a medicine.


References

Castelvetro, G. The Fruit, Herbs and Vegetables of Italy. 1611. G,.Riley, translator. Viking Press, London.1989.
Davidson, K. 5 Interesting Types of Lettuce healthline.com https://www.healthline.com/nutrition/types-of-lettuce 2019. Accessed 12/5/19.
“lettuce, n.”. OED Online. September 2019. Oxford University Press.  (Accessed December 02, 2019.
Lindqvist, K. On the origin of cultivated lettuce. Hereditas. 46: 319-350. 1960.
Ryder, E. J. and T. W. Whitaker, Lettuce Lactuca sativa (Compositae) pp. 53- Smartt and Simmonds, Evolution of Crop Plants, Longman Press, London.
USDA, NRCS. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA. 2019. http://plants.usda.gov. Accessed 6 December, 2019.

Updated on Dec 10, 2019  |  Originally Published on Jan 1, 1970

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