Next is the perennial, burger-topping iceberg lettuce. You'll need 33 cups of ... This pretty red and green leaf is chard. And it's a powerhouse. We're talking 300% of your daily vitamin K.

At the supermarket, you'll find a wide selection of leafy greens: from tender baby spinach to crunchy romaine, soft butter lettuce and spicy arugula. How do these greens differ nutritionally?

Lettuce (Lactuca sativa) is a leafy green plant belonging to the daisy family, Asteraceae. Originating in the Mediterranean region, it is one of the oldest cultivated crops known to humankind ...