Lactuca n. : A genus of composite herbs, several of which are cultivated foe salad; lettuce.

Example:
Is it safe to make your own lettuce opium from wild Lactuca serriola?

Taxonomy
Lactuca, China, Lettuce, North America, tropical Africa, Japan, Lactuca canadensis, Korea, Congo, Himalaya, Iran, Afghanistan, Asia Minor, India, Southern Europe, Wild Lettuce, Blue Lettuce, Angola.

Defination from the web:
Lactuca sativa), with its many varieties. ... Lactuca species are used as food plants by the larvae of a number of Lepidoptera species - see list of Lepidoptera that feed on lettuces. Wild Lettuce (Lactuca virosa) ...