2. BUTTERHEAD LETTUCE
One of the five main types of leafy greens of the Lactuca sativa, or lettuce, species (the others are loose-leaf, crisphead, batavian, and romaine), butterhead lettuces include boston and bibb (named after a 19th-century Kentucky vegetable grower) and can be identified by their supple, rounded leaves. Heirloom varieties include grandpa admire's; a reddish French lettuce called merveille des quatre saisons; and one of the oldest, tennis ball, a favorite of Thomas Jefferson's. The sweet, delicate flavor of these lettuces is best brought out when they're tossed sparingly with a tart dressing or a vinaigrette.