Head lettuces, trays

Lettuce is from the Lactuca Genus, and they belong to the Asteraceae family, that has over 1000 genus and 20000 species, of which very few are grown. This family, whose name comes from the greek Aster (star), is characterized because its flowers are made by the fusion of hundreds or even thousands of small flowers. Among the asteraceae there are many kinds of vegetables:  of leafs (chicory, lettuce, endive, curly endive), of flower (artichoke) or of stem (thistle). The scientific name Lactuca Sativa also includes heads and lettuces with a small stem that have a head similar to that of a cabbage.