Romaine lettuce, also known as cos lettuce, is a type of lettuce (and a vegetable) that is characterized by dark green leaves that grow upright and curl inward from lighter colored stems. These leaves are particularly fragile compared to other types of lettuce and are often damaged in shipment, making it the least widely grown type of lettuce. It also happens to be the most nutritious and the main choice of lettuce used in Caesar salads. Other similar varieties include a sweet romaine and a more mild variety that is characterized by red-tipped leaves.
The deeper green colors of romaine lettuce give it a deeper and more flavorful taste than other types of lettuce such as butterhead and crisphead lettuce. The inner leaves of this lettuce have a lighter color than the outside leaves, resulting in a lighter flavor as well. Like some the others, cos lettuce is also a crunchy lettuce, but the darker green parts of the leaves happen to be softer than the light-colored stems.
The nutritional benefits of romaine lettuce include an abundance of vitamin A, beta-carotene, vitamin K, folic acid and vitamin C to name a few. All of these nutrients are essential for a diet that is considered to be healthy for the heart, and can be an important part of any daily diet. Not only this, but romaine is also listed as a food that fights cancer by the American Institute for Cancer Research.
When buying romaine lettuce, one should try to avoid heads with “rust” spots and wilted leaves as well as older plants with decay and browning. Keep in mind also that a package of pre-chopped romaine lettuce will typically not last as long as a whole head, even if the package is well sealed. Ideally, the lettuce should be stored between 33 and 35 degrees Fahrenheit.