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.
Loose leaf lettuce actually covers a variety of lettuce leaves and is defined as lettuce leaves that donât form heads as they grow. Loose leaf lettuce is a great plant for home-growers as the leaves can be frequently picked without halting the growth of the rest of the plant. Butter lettuce, including Bibb and Boston lettuces, are mild green on the outer leaves, yellow-green on the inside, and have a soft, velvety or âbutteryâ texture.