Lettuce and spinach are the start of many a great salad. Both low in calories and nutritious, one cup of raw salad greens counts as a serving of vegetables in the USDA's Food Guide Pyramid.
Lettuce varieties that are dark green and reddish in color are the most nutritious. But even popular, but pale, iceberg lettuce provides water, fiber, folate, and small amounts of other important vitamins and minerals like zinc and potassium. The outer leaves of these varieties pach the most nutrition.
Spinach is thought to have originated in Persia, although our name for it comes from the French, which in turn came from the Arabic and Persian words.
Contrary to popular belief, it is not always best to get the firmest head of lettuce. The best tasting lettuce will not be rock solid. If you buy the firmest head, you will get more lettuce for your money, but it may not have the best possible flavor.
Modern lettuce had its start as a Mediterranean weed. As early as 55 B.C., lettuce was served on the tables of Persian kings and praised for its medicinal values. The name comes from Latin words referring to its milky juice.
Watercress was always carried with Greek, Roman and Persian soldiers during their campaigns and eaten for its anti-scorbutic properties, to prevent scurvy.