Lactuca serriola has a spineless reddish stem, containing a milky latex, growing up to 2 metres (6 ft 7 in).

[5][6] Lactuca serriola is known as the compass plant because in the sun the upper leaves twist round to hold their margins upright.

[12] The possible combinations of these Dm genes can provide the plant with resistance to multiple strains of Bremia lactucae.

[15] This genetic diversity is considered a resource for lettuce breeding because it provides a greater variety of genes to be used in response to new strains of B. lactucae, which continually emerge.

[12][15] There is especially high diversity within the Mediterranean area and Southwest Asia, but L. serriola has established populations on all continents and has the most widespread distribution compared to other Lactuca species.

The Ancient Greeks also believed its pungent juice to be a remedy against eye ulcers and Pythagoreans called the lettuce eunuch because it caused urination and relaxed sexual desire.

[21] In the island of Crete in Greece the leaves and the tender shoots of a variety called maroula (μαρούλα) or agriomaroulo (αγριομάρουλο) are eaten boiled.

[citation needed] Lactuca serriola contains lactucarium, which is the milky sap (white latex) that flows through the stem of the plant.

Also, archaeobotanical evidence in Greek archaeological contexts is scanty, although uncarbonised seeds have been retrieved from a 7th-century BC deposit in a sanctuary of Hera on Samos.

In mythology, Aphrodite is said to have laid Adonis in a lettuce bed, leading to the vegetable's association with food for the dead.