Annona muricata, called soursop due to the sweet and sour flavor of the large fruit, is a lowland tropical fruit-bearing tree in the Annonaceae family. Related species include cherimoya (A. cherimola) and sugar-apple (A. squamosa); paw paw (Asimina triloba) is also in the family. Other common names include graviola and guanábana (sometimes shortened to guanába). The soursop is native to tropical Central and South America and the Caribbean, but is now widely cultivated in tropical areas worldwide, including southern Florida and Southeast Asia, from sea level to altitudes of around 1150 meters. It has occasionally escaped cultivation and become naturalized (Wikipedia 2011, Flora of Pakistan 2011). It is considered invasive in the Galápagos, French Polynesia, Hawaii, Tonga, and Australia (PIER 2011).
Soursop is a slender, small, and cold-intolerant tree, generally reaching heights of 4–6 meters (13–20 feet); it flowers at can bear fruit 3–5 years after planting. Leaves are glossy, dark green, and generally evergreen, with a distinctive odor (Morton 1987). Its fruits are the largest of the Annona species, 20–30 cm (8–12 in) long, often weighing 4.5 kg, with exceptional fruits as large as 7 kg (Flora of Pakistan 2011, NAS 1989). The fruits have green inedible skins, with many soft, curved spines, but the white, juicy pulp is edible. It has an aroma of pineapple but a sour or musky flavor, and is eaten fresh or used for making juices and other beverages (including the Cuban “champola de guanábana), as well as custards and sherbets and other dishes in South America, the Caribbean, and Indonesia (Morton 1987, Popenoe 1920).