Lactuca

Lactuca, commonly known as lettuce, is a genus of flowering plants in the family Asteraceae. The genus includes at 117 recognized species, distributed worldwide, but mainly in temperate Eurasia. Its best-known representative is the garden lettuce (Lactuca sativa), with its many varieties. "Wild lettuce" commonly refers to the wild-growing relatives of common garden lettuce. Many species are common weeds. Lactuca species are diverse and take a wide variety of forms. They are annuals, biennials, perennials, or shrubs. Their flower heads have yellow, blue, or white ray florets. Some species are bitter-tasting. Most wild lettuces are xerophytes, adapted to dry habitat types. Some occur in more moist areas, such as the mountains of central Africa. Research revealed substantial genome size variation within the genus, ranging from 2.1 Gb in ''L. saligna'' to 5.5 Gb in ''L. indica''. This expansion is primarily driven by the proliferation of repetitive elements and is associated with low DNA methylation levels (specifically CHH methylation) and reduced expression of the ''CMT2'' gene