Also called sugar apple, the sweetsop is the egg-shaped fruit of a small tropical-American tree belonging to the genus Annona. The sweetsop (A. squamosa) is one of several members of the Annona family, including cherimoya and soursop. It has a thick, coarse yellow-green (sometimes purple-tinged) skin and yellow flesh with dark seeds. Often mistaken for its cousin, the cherimoya, the sweetsop has a very sweet, custardlike flesh that's divided into segments like a citrus fruit. It's grown in Florida and California and is usually available from midsummer to midwinter only in the locales where it's grown. After the skin and seeds are removed, sweetsops are usually eaten raw and often used in desserts.
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.