Lettuce, however, is often found growing wild, and cultivated lettuce is closely related to the wild lettuce, from which it was doubtless derived. Wild lettuce is now widely scattered over the globe, but it originated in inner Asia Minor, the Caucasus, Iran, and Turkistan.
When you shop for fresh fruits and vegetables in your local supermarket, you will see that some items have labels showing their varietal name while others remain unmarked. You can ask the produce manager for help in distinguishing different varieties of unlabeled items but chances are that they are just as bewildered. When you buy apples, for example, the name of each is clearly listed. You can easily select a Fuji, a Gala, or Red Delicious. The same is true when shopping for avocados, cherries, grapes, mushrooms, onions, oranges, pears, plums, and a number of other fruits and vegetables. This is almost never true when shopping for lettuce and other greens, however. When you buy some lettuce you may see it identified as Iceberg, Romaine or Leaf lettuce but just what variety of each is still a mystery especially with the loose leaf greens.
The next most nutritious greens are dark green in color. Dark green varieties are rich in a phytonutrient called lutein, which is another potent antioxidant and has been shown to protect eye health and calm inflammation. As a general rule, lettuce varieties with light green leaves can be avoided as they give you the fewest health benefits. Suggested varieties of dark green lettuce to try include Boston Lettuce, Butter Crunch, Cocarde, Concept, Green Oak, Green Romain, Green Towers, Little Gems, Nevada and Summertime.
A second trait to look for is the arrangement of the individual leaves on a lettuce plant. When a lettuce plant has leaves that are tightly wrapped like a cabbage’s, the phytonutrient content tends to be very low.
This is true of iceberg lettuce and other crisp head varieties. Plants with loose and open leaves, particularly the Leaf varieties, contain many times more phytonutrients. As a rule, plants that have a combination of open and wrapped leaves, such as Romaine and Bibb lettuce, have moderate amounts.