The papaya (, ), papaw, () or pawpaw () is the plant species Carica papaya, one of the 21 accepted species in the genus Carica of the family Caricaceae. It was first domesticated in Mesoamerica, within modern-day southern Mexico and Central America. It is grown in several countries in regions with a tropical climate. In 2020, India produced 42% of the world's supply of papayas.
Etymology
The word papaya derives from Arawak via Spanish. The name papaw or pawpaw is used for the same fruit in some regions.
Description
The papaya is a small, sparsely branched tree, usually with a single stem growing from tall, with spirally arranged leaves confined to the top of the trunk. The lower trunk is conspicuously scarred where leaves and fruit were borne. The leaves are large, in diameter, deeply palmately lobed, with seven lobes. All plant parts contain latex in articulated laticifers.
Flowers
Papayas are dioecious. The flowers are five-parted and highly dimorphic; the male flowers have the stamens fused to the petals. The female flowers have a superior ovary and five contorted petals loosely connected at the base.
Male and female flowers are borne in the leaf axils; the male flowers are in multiflowered dichasia, and the female ones are in few-flowered dichasia. The pollen grains are elongated and approximately 35 microns in length. The flowers are sweet-scented, open at night, and wind- or insect-pollinated.
Fruit
The fruit is a large berry about long and in diameter. It is ripe when it feels soft (as soft as a ripe avocado or softer), its skin has attained an amber to orange hue and along the walls of the large central cavity are attached numerous black seeds.
Chemistry
Papaya skin, pulp, and seeds contain a variety of phytochemicals, including carotenoids and polyphenols, as well as benzyl isothiocyanates and benzyl glucosinates, with skin and pulp levels that increase during ripening. The carotenoids, lutein and beta-carotene, are prominent in the yellow skin, while lycopene is dominant in the red flesh (table). Papaya seeds also contain the cyanogenic substance prunasin. The green fruit contains papain, a cysteine protease enzyme used to tenderize meat (see below).
Distribution and habitat
Native to tropical America, papaya originates from southern Mexico and Central America. Papaya is also considered native to southern Florida, introduced by predecessors of the Calusa no later than 300 CE. Spaniards introduced papaya to the Old World in the 16th century. Papaya cultivation is now nearly pantropical, spanning Hawaii, central Africa, India, and Australia.
Wild populations of papaya are generally confined to naturally disturbed tropical forests. Papaya is found in abundance on Everglades hammocks following major hurricanes, but is otherwise infrequent. In the rain forests of southern Mexico, papaya thrives and reproduces quickly in canopy gaps while dying off in the mature closed-canopy forests.
Ecology
Viruses
Papaya ringspot virus is a well-known virus within plants in Florida. The first signs of the virus are yellowing and vein-clearing of younger leaves and mottling yellow leaves. Infected leaves may obtain blisters, roughen, or narrow, with blades sticking upwards from the middle of the leaves. The petioles and stems may develop dark green greasy streaks and, in time, become shorter. The ringspots are circular, C-shaped markings that are a darker green than the fruit. In the later stages of the virus, the markings may become gray and crusty. Viral infections impact growth and reduce the fruit's quality. One of the biggest effects that viral infections have on papaya is taste. As of 2010, the only way to protect papaya from this virus is genetic modification.
The papaya mosaic virus destroys the plant until only a small tuft of leaves is left. The virus affects both the leaves of the plant and the fruit. Leaves show thin, irregular, dark-green lines around the borders and clear areas around the veins. The more severely affected leaves are irregular and linear in shape. The virus can infect the fruit at any stage of its maturity. Fruits as young as two weeks old have been spotted with dark-green ringspots about 1 inch (25 mm) in diameter. Rings on the fruit are most likely seen on either the stem end or the blossom end. In the early stages of the ringspots, the rings tend to be many closed circles, but as the disease develops, the rings increase in diameter consisting of one large ring. The difference between the ringspot and the mosaic viruses is the ripe fruit in the ringspot has a mottling of colors, and the mosaic does not.