Algebra - Abstract algebra. 1  Abstract algebra extends the familiar concepts found in elementary algebra and arithmetic of numbers to more general concepts.
Choose the freshest looking lettuce for storing. Photo Credit anna1311/iStock/Getty Images. Romaine lettuce's high water content means there is no long-term preservation method suitable for making the lettuce last longer. Drying, canning and freezing all produce inedible results. For the best nutritional value, romaine lettuce is best served when it's fresh, green and crisp. Storing the lettuce in a refrigerator is the best option for preserving it, although there are a few other measures that can be taken to ensure romaine lettuce lasts as long as possible.
Types of Lettuce. In the United States, an 1885 agricultural report listed no fewer than 87 varieties of lettuce. Today, there are four basic types of lettuce: butterhead, iceberg, loose leaf, and romaine. You are likely to find all of these in the produce sections of most supermarkets. Butterhead lettuce: This type includes Boston and Bibb lettuces, which are characterized by a loose head and grass-green leaves. Both have a soft âbutteryâ texture and a sweet, mild flavor. A head of Boston lettuce resembles a flowering rose. Bibb lettuceâalso called limestoneâforms a smaller, cup-shaped head.