Olives may appear, along with rucola or romaine lettuce to augment the basil. Romaine lettuce is commonly used in Middle Eastern cuisine. The contamination came from the chopped romaine lettuce used in these products. Romaine lettuce, tomatoes and cucumbers are the main ingredients. They colonize romaine lettuce at all life stages after emergence. The most common vegetables used as bitter herbs are horseradish and romaine lettuce. The South grew artichokes, melons, romaine lettuce, eggplant, salsifys, celery, fennel, parsley, and alfalfa. They also serve made-to-order salads, romaine lettuce wraps, soups, and cookies. Romaine lettuce may be used in the Passover Seder as a type of bitter herb.