Romaine or cos lettuce (Lactuca sativa L. var. longifolia) is a variety of lettuce

Lettuce

Lettuce is a temperate annual or biennial plant of the daisy family Asteraceae. It is most often grown as a leaf vegetable. It is eaten either raw, notably in salads, sandwiches, hamburgers, tacos, and many other dishes, or cooked, as in Chinese cuisine in which the stem becomes just as important...

 which grows in a tall head of sturdy leaves with a firm rib down the center. Unlike most lettuces, it is tolerant of heat. The name cos lettuce derives from the Greek

Greece

Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....

 island of Kos

Kos

Kos or Cos is a Greek island in the south Sporades group of the Dodecanese, next to the Gulf of Gökova/Cos. It measures by , and is from the coast of Bodrum, Turkey and the ancient region of Caria. Administratively the island forms a separate municipality within the Kos peripheral unit, which is...

, where it originated.

Cuisine

The thick ribs, especially on the older outer leaves, should have a milky fluid which gives the romaine the typically fine-bitter herb taste.

Romaine is the usual lettuce used in Caesar salad

Caesar salad

A Caesar salad is a salad of romaine lettuce and croutons dressed with parmesan cheese, lemon juice, olive oil, egg, Worcestershire sauce, garlic, and black pepper. It may be prepared tableside.-History:...

.

Romaine is the usual lettuce in Middle Eastern cuisine

Middle Eastern cuisine

Middle-Eastern cuisine, West Asian cuisine, or in some place in the United States, Persian-Mediterranean cuisine is the cuisine of the various countries and peoples of the Middle East . The cuisine of the region is diverse while having a degree of homogeneity...

.

Ritual use

Romaine lettuce may be used in the Passover Seder

Passover Seder

The Passover Seder is a Jewish ritual feast that marks the beginning of the Jewish holiday of Passover. It is conducted on the evenings of the 14th day of Nisan in the Hebrew calendar, and on the 15th by traditionally observant Jews living outside Israel. This corresponds to late March or April in...

 as a type of bitter herb

Maror

Maror also Marror, refers to the bitter herbs eaten at the Passover Seder in keeping with the biblical commandment "with bitter herbs they shall eat it." .-Biblical source:...

, to symbolise the bitterness inflicted by the Egyptians while the Israelites were slaves in Egypt.

The day of 22 Germinal

Germinal (French Republican Calendar)

Germinal was the seventh month in the French Republican Calendar. The month was named after the Latin word germen, which means germination...

 in the French Republican Calendar

French Republican Calendar

The French Republican Calendar or French Revolutionary Calendar was a calendar created and implemented during the French Revolution, and used by the French government for about 12 years from late 1793 to 1805, and for 18 days by the Paris Commune in 1871...

is dedicated to this lettuce.

Nutrition

As with other dark leafy greens, the antioxidants contained within romaine lettuce are believed to help prevent cancer. According to the 2011 edition of the Old Farmer's Almanac, the chlorophyll pigment in dark leafy greens, such as Romaine lettuce, may reduce levels of colon and liver cancer carcinogens.