Its origins are vague, but the native Jamaican ugli fruit (also called uniq fruit) is believed to be a tangerine-grapefruit hybrid (though the pomelo may also have been involved). It ranges in size between that of a navel orange and a giant grapefruit. Its acid-sweet flavor suggests grapefruit with hints of orange. The extremely thick, yellow-green skin fits rather loosely over the large, juicy, yellow-orange pulp sections. Ugli fruit is available on a limited basis from winter to spring. Choose fruit that's heavy for its size and that gives slightly to palm pressure. Store at room temperature and use within 5 days or refrigerate up to 3 weeks. Ugli fruit may be prepared and eaten in any way suitable for grapefruit. It's an excellent source of vitamin C.
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.