Carica papaya, papaya is a giant herbaceous plant--resembling a tree but not woody--in the Caricaceae (papaya family) that originated in Central America and is now grown in tropical areas world-wide for its large, sweet, melon-like fruits. The name “papaya” also refers to the fruit of other Carica species, including C. pubescens and C. stipulata, and their various hybrids.
Sometimes called paw-paw, although that name more typically applies to the species Asimona triloba, the papaya plant has a hollow, green or purple stem, and can grow 1.8 to 3 m (6 to 10 ft) in a year, eventually reaching heights of 6 to 9 m (20 to 30 ft). The long-petioled (stemmed) leaves, which may be 30 to 105 cm long (1 to 3.5 ft) and 30 to 60 cm (1 to 2 ft) wide, are deeply divided into 5 to 9 main segments, which are further lobed. Both leaves and stems contain large amounts of white, milky latex.
Papaya plants are generally dioecious, with short-stalked female (pistillate) flowers, which are 5-petalled, waxy, and white, borne on separate plants from the male (staminate) flowers, which are borne on long panicles (up to 1.8 m or 6 ft). Plants may also bear hermaphroditic or perfect flowers, which have both pistils and stamens, or they may be monoecious, bearing separate male and female flowers on the same plant. The fruit that develops varies in shape depending on the flower type. Fruits from female flowers are usually oval to round and smaller than the fruits that develop from perfect flowers, which are cylindrical or club-shaped, up to 50 cm (20 in) long and 20 cm (8 in) wide. The fruits, which can weigh up to 9 kg (20 lbs)—although common commercial cultivars generally produce fruits that weigh 0.5 to 2.25 kg (1 to 5 lbs)—and have a thin but tough waxy skin. Green fruits contain latex, which disappears as the fruit ripens to light or dark yellow. The flesh of the fruit varies from yellow to orange to red, and is thick and juicy, with a central cavity filled with many small black seeds.
Papayas, which are high in vitamins A and C and calcium, are often used fresh in fruit salads and desserts, as well as prepared in juices and jams or dried. Some Southeast Asian dishes call for the unripe fruits to be cooked and used as vegetables. Papayas produce an enzyme, papain, which aids digestion and is used to tenderize meat. Papain has been used in medicine to treat ulcers and reduce skin adhesions following surgery, and studies have shown that it has antimicrobial properties. Papain is also used to clarify beer, prepare wool and silk for dyeing, and remove hair from hides before tanning, among other uses.
The FAO estimates that total commercial production of papayas in 2010 was 11.2 million metric tons, harvested from nearly 439,000 hectares, India is the leading producer of papayas, responsible for 42% of the world’s crop. Other major producers include Brazil, Nigeria, Indonesia, and Mexico. Papayas were previously grown in Florida, but they are susceptible to numerous pests and pathogens, including mosaic viruses transmitted by aphids including Myzus persicae, that have wiped out most commercial plantings there.
(Bailey et al. 1976, FAO 2012, Hedrick 1919, Morton 1987, van Wyk 2005.)