Escarole is related to Belgian and curly endive but has broad, slightly curved pale green leaves with a milder flavor than either of them. Both curly endive and escarole are available year-round, with the peak season from June through October. They should be selected for their fresh, crisp texture; avoid heads with discoloration or insect damage. Store curly endive and escarole tightly wrapped in the refrigerator for up to three days. They're both used mainly in salads but can also be briefly cooked and eaten as a vegetable or in soups.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.