Romaine lettuce is a tall, sturdy green leaf tinged with red. Red leaf lettuce is more fragile than green lettuce, and has less of a crunch. Red lettuce also has a mild nutty flavor.
Be on the lookout for wilting. Check the dark purple edges of the leaves to be sure they are not brown. Store unwashed in a plastic bag in the refrigerator, and it should last a few days.
Wash very well before using, then dry thoroughly. A salad spinner works well to dry. Remove the core. with a knife. Red leaf with mandarin oranges and a wine vinaigrette would make a great salad. So would apples and parmesan.