Carica papaya, the papaya, is a small, fast-growing but short-lived, evergreen tree growing 3 - 10 metres tall with a bole 10 - 30cm in diameter. The plant is usually without side-branches, although these can be produced if the plant is injured or the growing tip is removed.
Although it adopts the habit of a tree, the bole is non-woody and somewhat hollow.
One of the most popular and delicious of tropical fruits, papaya is widely cultivated in tropical and subtropical areas around the world. The tree also has a wide range of other uses, particularly for the medicinal value of its fruits and leaves.

Known Hazards

Older leaves contain the alkaloid carpaine.

Habitat

Not known as a truly wild plant

Cultivation Status

Cultivated

Cultivation Details

Papaya succeeds in tropical and subtropical areas, where it can be found between 32°N and S. It produces best at elevations below 900 metres, though it can also succeed as high as 2,100 metres near the equator.
It grows best in areas where annual daytime temperatures are within the range 21 - 30°c, but can tolerate 12 - 44°c.
It can be killed by temperatures of -1°c or lower. It prefers a climate with well distributed rainfall and a mean annual rainfall in the range 1,500 - 2,500mm, but tolerates 1,000 - 3,000mm.
Low temperatures cause smaller fruit size and low quality.
Prefers a sunny position in a deep, humus- rich soil.
Requires a well-drained, well-aerated soil, trees can die within a few days if the soil becomes waterlogged.
Grows best in a position sheltered from strong winds.
Plants produce masses of easily damaged feeding roots near the surface and so are best hand weeded when young and given a good organic mulch as they grow.
Prefers a pH in the range 5.5 - 7, tolerating 4.5 - 8.
A very productive plant, it can start to crop when only 6 months old and can produce fruit all year round.
Yields of between 22 - 56 tonnes/ha of fresh fruit are obtained in Hawaii and yields up to 80 tonnes/ha have been reported. The yields are highest in the second and third year and they then decline rapidly.
The productive life of a tree is very short, yields have declined sharply by the time it is four years old.
There are many named varieties.
Individual plants can bear only male flowers, only female flowers or hermaphrodite flowers. One male plant will be enough to fertilize 6 or more females.
Hand pollinated fruits ripen after about 150 - 240 days.

Edible Uses

Fruit - raw or cooked. The vitamin-rich fruit has a firm, creamy texture and a delightful flavour reminiscent of melon and apricot. Delicious raw, it is a very versatile fruit and can also be preserved, dried, cooked in pies, made into jam, ice cream, jellies, sherbets etc.
The immature green fruit can be eaten as a vegetable, either boiled, baked, made into chutneys, jams or added to vegetable soups etc.
Seeds - used as a spice, especially in salad dressings. A pungent, mustard and cress-like flavour.
Male flowers - cooked and used as a green vegetable. A bitter flavour, it is probably best to change the water at least once during the cooking.
Very young leaves - cooked. A strong bitter flavour. Some caution is advised since older leaves contain alkaloids.

Medicinal

The skin of the unripe fruit, the leaves, sap and seeds of the papaya are all a source of the enzyme papain, a digestive stimulant that facilitates the digestion of protein.
The unripe fruit is an especially good source.
Papain can be used internally, especially in the form of the extracted enzyme, to treat digestive disorders.
It is also applied externally to aid the healing of deep or slow-healing wounds.
An infusion of the young, latex-filled, green fruit is used as a children's vermifuge.
The juice of the fruit is used to treat diabetes and hypertension.
The immature fruit, sometimes combined with aspirin, is used as an abortifacient.
The fruit pulp is mixed with fat in a pomade to remedy abscesses.
The juice of the fruit is used to dissolve warts.
The leaves and the fruit, especially the unripe fruit, are taken internally in the treatment of a range of digestive disorders, diarrhoea, high blood pressure and painful womb.
The green leaves are cooked as a treatment for tertiary malaria and for irregular bowel movement in children.
Externally, the leaves are applied to wounds as a dressing that helps to speed the healing process.
The leaves and seeds are used locally to rid the body of threadworms and roundworms.
The seeds are used as a gentle purgative to rid the body of worms.
Immature seeds are swallowed to treat diarrhoea.
The seed is eaten as a children's vermifuge, and also to increase visual acuity.
The latex from the trunk of the tree has a strong purgative action when taken internally and is sometimes used to rid the body of worms.
The latex is applied externally to wounds, boils, ulcers, warts and cancerous tumours in order to speed their healing.
It is also applied to the gums to treat toothache.
The ripe fruit is a mild laxative.
A decoction of the ripe fruit is used to treat persistent diarrhoea and dysentery in children.
An infusion of the flowers is drunk in order to induce menstruation, and also to treat laryngitis, bronchitis and venereal diseases.
The flowers are used in combination with milk and butter as an appetite stimulant.
The bark is used to treat diarrhoea.
The inner bark is used to treat toothache.
The root is aphrodisiac, astringent and vermifuge.
The macerated root is used in the treatment of gonorrhoea.
An infusion of the root in alcohol is used to treat bladder and kidney problems.
A decoction is drunk to treat abdominal stricture, diarrhoea, malaria and intestinal worms.
Applied externally, an infusion of the root in alcohol is rubbed on the limbs to treat rickets.
A decoction of the root is used externally to treat abdominal stricture.
The latex contains the protein-degrading (proteolytic) and mucolytic enzymes papain and chymopapain.
The plant contains hydrocyanic acid, carpaine, terpene hydrocarbons, terpene alcohols, cyanogenic glycosides.

Agroforestry Uses

Young leaves are used as mulch.

Other Uses

The dried leaves can be beaten in water to form a soap substitute.
Papain, found in its greatest concentration in the latex in the skin of unripe fruits, has a multitude of uses. It is added to cosmetic skin creams, termite control, used in clarifying beer, degumming natural silk etc.
A fibre obtained from the plant can be up to 150cm long, but it is of questionable utility.
The whitish or pale yellow wood is very soft, very lightweight, and fleshy. There is a large white pith, and the centre of the trunk is hollow except at nodes. The wood is not used.

Propagation

Seed - best sown as soon as ripe in a position in indirect light. Germination takes 2 - 6 weeks at 24 - 30°c.
Move to a sunny position about 2 weeks after germination.
Greenwood cuttings.
Grafting.