Tropical Plant Database - Plant Details

Commonly and erroneously referred to as a "tree", the plant is properly a large herb growing at the rate of 6 to 10 ft (1.8-3 m) the first year and reaching 20 or even 30 ft (6-9 m) in height, with a hollow green or deep-purple stem becoming 12 to 16 in (30-40 cm) or more thick at the base and roughened by leaf scars. The leaves emerge directly from the upper part of the stem in a spiral on nearly horizontal petioles 1 to 3 1/2 ft (30-105 cm) long, hollow, succulent, green or more or less dark purple. The blade deeply divided into 5 to 9 main segments, each irregularly subdivided, varies from 1 to 2 ft (30-60 cm) in width and has prominent yellowish ribs and veins. The life of a leaf is 4 to 6 months. Both the stem and leaves contain copious white milky latex.
The 5-petalled flowers are fleshy, waxy and slightly fragrant. Some plants bear only short-stalked pistillate (female) flowers, waxy and ivory-white, or hermaprodite (perfect) flowers (having female and male organs), ivory-white with bright-yellow anthers and borne on short stalks. Other plants may bear only staminate (male) flowers, clustered on panicles to 5 or 6 ft (1.5-1.8 m) long. There may even be monoecious plants having both male and female flowers. Some plants at certain seasons produce short-stalked male flowers, at other times perfect flowers. This change of sex may occur temporarily during high temperatures in midsummer. Some "all-male" plants occasionally bear, at the tip of the spray, small flowers with perfect pistils and these produce abnormally slender fruits. Male or hermaphrodite plants may change completely to female plants after being beheaded.
Generally, the fruit is melon-like, oval to nearly round, somewhat pyriform, or elongated club-shaped, 6 to 20 in (15-50 cm) long and 4 to 8 in (10-20 cm) thick, weighing up to 20 lbs (9 kg). Semi-wild (naturalized) plants bear miniature fruits 1 to 6 in (2.5-15 cm) long. The skin is waxy and thin but fairly tough. When the fruit is green and hard it is rich in white latex. As it ripens, it becomes lighter in color or deep-yellow externally and the thick wall of succulent flesh becomes aromatic, yellow, orange or various shades of salmon or red. It is then juicy, sweetish and somewhat like a cantaloupe in flavor and in some types quite musky. Attached lightly to the wall by soft, white, fibrous tissue, are usually numerous small, black, ovoid, corrugated, peppery seeds about 3/16 in (5 mm) long, each coated with a transparent, gelatinous aril.
Fruits from bisexual plants are usually cylindrical or pyriform with small seed cavity and thick wall of firm flesh which stands handling and shipping well. In contrast, fruits from female flowers are nearly round or oval and thin-walled. In some areas, bisexual types are in greatest demand. In South Africa, round or oval Papayas are preferred.
(Morton, J. 1987. Fruits of Warm Climates.)

In tropical folk medicine, the fresh latex is smeared on boils, warts and freckles and given as a vermifuge. In India, it is applied on the uterus as an irritant to cause abortion. The unripe fruit is sometimes hazardously ingested to achieve abortion. Seeds, too, may bring on abortion. They are often taken as an emmenagogue and given as a vermifuge. The root is ground to a paste with salt, diluted with water and given as an enema to induce abortion. A root decoction is claimed to expel roundworms. Roots are also used to make salt.
Crushed leaves wrapped around tough meat will tenderize it overnight. The leaf also functions as a vermifuge and as a primitive soap substitute in laundering. Dried leaves have been smoked to relieve asthma or as a tobacco substitute. Packages of dried, pulverized leaves are sold by "health food" stores for making tea, despite the fact that the leaf decoction is administered as a purgative for horses in Ghana and in the Ivory Coast it is a treatment for genito-urinary ailments. The dried leaf infusion is taken for stomach troubles in Ghana and they say it is purgative and may cause abortion.
(Morton, J. 1987. Fruits of Warm Climates.)

Papaya Allergy:

Mention has already been made of skin irritation in papaya harvesters because of the action of fresh papaya latex, and of the possible hazard of consuming undercooked meat tenderized with papain. It must be added that the pollen of papaya flowers has induced severe respiratory reactions in sensitive individuals. Thereafter, such people react to contact with any part of the plant and to eating ripe Papaya or any food containing papaya, or meat tenderized with papain.
(Morton, J. 1987. Fruits of Warm Climates.)

The green fruits of papaya may be allowed to ripen and can be eaten locally, or they can be employed for making dried papaya "leather" or powdered Papaya, or may be utilized as a source of pectin.
Because of its papain content, a piece of green papaya can be rubbed on a portion of tough meat to tenderize it. Sometimes a chunk of green papaya is cooked with meat for the same purpose.
One of the best known uses of papain is in commercial products marketed as meat tenderizers, especially for home use. Papain-treated meat should never be eaten "rare" but should be cooked sufficiently to inactivate the enzyme.
Papain has many other practical applications. It is used to clarify beer, also to treat wool and silk before dyeing, to de-hair hides before tanning, and it serves as an adjunct in rubber manufacturing. It is applied on tuna liver before extraction of the oil which is thereby made richer in vitamins A and D.
Papain enters into toothpastes, cosmetics and detergents, as well as pharmaceutical preparations to aid digestion.
The Papaya latex is obtained by making incisions on the surface of the green fruits early in the morning and repeating every 4 or 5 days until the latex ceases to flow. The tool is of bone, glass, sharp-edged bamboo or stainless steel (knife or raxor blade). Ordinary steel stains the latex. Tappers hold a coconut shell, clay cup, or glass, porcelain or enamel pan beneath the fruit to catch the latex, or a container like an "inverted umbrella" is clamped around the stem. The latex coagulates quickly and, for best results, is spread on fabric and oven-dried at a low temperature, then ground to powder and packed in tins. Sun-drying tends to discolor the product. One must tap 1,500 average-size fruits to gain 1 1/2 lbs (.68 kg) of papain.
In India, papaya seeds are sometimes found as an adulterant of whole black pepper. A yellow to brown, faintly scented oil was extracted from the sundried, powdered seeds of unripe papayas at the Central Food Technological Research Institute, Mysore, India. White seeds yielded 16.1% and black seeds 26.8% and it was suggested that the oil might have edible and industrial uses.

Successful commercial production today is primarily in Hawaii, tropical Africa, the Philippines, India, Ceylon, Malaya and Australia, apart from the widespread but smaller scale production in South Africa, and Latin America.
(Morton, J. 1987. Fruits of Warm Climates.)

Though the exact area of origin is unknown, the papaya is believed native to tropical America, perhaps in southern Mexico and neighboring Central America. (Morton, J. 1987. Fruits of Warm Climates.)

Ripe papayas are most commonly eaten fresh, merely peeled, seeded, cut in wedges and served with a half or quarter of lime or lemon. Sometimes a few seeds are left attached for those who enjoy their peppery flavor but not many should be eaten. The flesh is often cubed or shaped into balls and served in fruit salad or fruit cup. Firm-ripe Papaya may be seasoned and baked for consumption as a vegetable. Ripe flesh is commonly made into sauce for shortcake or ice cream sundaes, or is added to ice cream just before freezing or is cooked in pie, pickled, or preserved as marmalade or jam. Papaya and Pineapple cubes, covered with sugar sirup, may be quick-frozen for later serving as dessert. Half-ripe fruits are sliced and crystallized as a sweetmeat.
Papaya juice and nectar may be prepared from peeled or unpeeled fruit and are sold fresh in bottles or canned. In Hawaii, Papayas are reduced to puree with sucrose added to retard gelling and the puree is frozen for later use locally or in mainland USA in fruit juice blending or for making jam.
Unripe Papaya is never eaten raw because of its latex content. Even for use in salads, it must first be peeled, seeded, and boiled until tender, then chilled. Green Papaya is frequently boiled and served as a vegetable. Cubed green Papaya is cooked in mixed vegetable soup.
Green Papaya is commonly canned in sugar sirup in Puerto Rico for local consumption and for export.
Young leaves are cooked and eaten like spinach in the East Indies. Mature leaves are bitter and must be boiled with a change of water to eliminate much of the bitterness.
Sprays of male flowers are sold in Asian and Indonesian markets and in New Guinea for boiling with several changes of water to remove bitterness and then eating as a vegetable. In Indonesia, the flowers are sometimes candied. Young stems are cooked and served in Africa. Older stems, after peeling, are grated, the bitter juice squeezed out, and the mash mixed with sugar and salt.
The Papaya is regarded as a fair source of iron and calcium, a good source of vitamins A, B and G and an excellent source of vitamin C (ascorbic acid).
(Morton, J. 1987. Fruits of Warm Climates.)

It is recorded that seeds of papaya were taken to Panama and then the Dominican Republic before 1525 and cultivation spread to warm elevations throughout South and Central America, southern Mexico, the West Indies and Bahamas, and to Bermuda in 1616. Spaniards carried seeds to the Philippines about 1550 and the papaya traveled from there to Malacca and India. Seeds were sent from India to Naples in 1626. Now the Papaya is familiar in nearly all tropical regions of the Old World and the Pacific Islands and has become naturalized in many areas.
In the 1950's an Italian entrepreneur, Albert Santo, imported Papayas into Miami by air from Santa Marta, Colombia, Puerto Rico and Cuba for sale locally as well as shipping fresh to New York, and he also processed quantities into juice or preserves in his own Miami factory.
Seeds were probably brought to Florida from the Bahamas. Up to about 1959, the papaya was commonly grown in southern and central Florida in home gardens and on a small commercial scale. Thereafter, natural enemies seriously reduced the plantings. There was a similar decline in Puerto Rico about 10 years prior to the setback of the industry in Florida. While isolated plants and a few commercial plots may be fruitful and long-lived, plants in some fields may reach 5 or 6 ft, yield one picking of undersized and misshapen fruits and then are so affected by virus and other diseases that they must be destroyed.
(Morton, J. 1987. Fruits of Warm Climates.)

Papaya leaves contain the bitter alkaloids, carpaine and pseudocarpaine, which act on the heart and respiration like digitalis, but are destroyed by heat. In addition, two previously undiscovered major D1-piperideine alkaloids, dehydrocarpaine I and II, which are more potent than carpaine, were reported from the University of Hawaii in 1979.

Collaborating chemists in Italy and Somalia identified 18 amino acids in Papaya seeds, principally, in descending order of abundance, glutamic acid, arginine, proline, and aspartic acid in the endosperm and proline, tyrosine, lysine, aspartic acid, and glutamic acid in the sarcotesta.

The latex of the Papaya plant and its green fruits contains two proteolytic enzymes, papain and chymopapain. The latter is most abundant but papain is twice as potent. In 1933, Ceylon (Sri Lanka) was the leading commercial source of papain but it has been surpassed by East Africa where large-scale production began in 1937.
Papain has been employed to treat ulcers, dissolve membranes in diphtheria, and reduce swelling, fever and adhesions after surgery.
With considerable risk, it has been applied on meat impacted in the gullet.
Chemopapain is sometimes injected in cases of slipped spinal discs or pinched nerves. Precautions should be taken because some individuals are allergic to papain in any form and even to meat tenderized with papain.

Antibiotic Activity:

Studies at the University of Nigeria have revealed that extracts of ripe and unripe Papaya fruits and of the seeds are active against gram-positive bacteria. Strong doses are effective against gram-negative bacteria. The substance has protein-like properties. The fresh crushed seeds yield the aglycone of glucotropaeolin benzyl isothiocyanate (BITC) which is bacteriostatic, bactericidal and fungicidal. A single effective does is 4-5 g seeds (25-30 mg BITC).
In a London hospital in 1977, a post-operative infection in a kidney-transplant patient was cured by strips of Papaya which were laid on the wound and left for 48 hours, after all modern medications had failed.
(Morton, J. 1987. Fruits of Warm Climates.)

We currently have 30 herbarium specimens for Carica papaya in our collection. Click on any specimen below to view the herbarium sheet data.

• 066207 - collected by C. R. Long in 1965
• 004567 - collected by Tim Flynn in 1984
• 004566 - collected by Tim Flynn in 1984
• 028437 - collected by Joel Lau in 1985
• 004568 - collected by Tim Flynn in 1987
• 003857 - collected by Art Whistler in 1989
• 030905 - collected by Jose Rivera Reyes in 1990
• 011700 - collected by Art Whistler in 1991
• 011444 - collected by Tim Flynn in 1991
• 044041 - collected by Liloa Dunn in 1998
• 037106 - collected by Diane Ragone in 2001
• 041831 - collected by E. Albert in 2001
• 039104 - collected by Stephanie Dunbar in 2002
• 053120 - collected by Michael J. Balick in 2002
• 046210 - collected by A. Dores in 2002
• 048650 - collected by A. Dores in 2002
• 089084 - collected by B. Ekiek in 2002
• 039394 - collected by David H. Lorence in 2003
• 039866 - collected by Liloa Dunn in 2003
• 046129 - collected by A. Dores in 2003
• 040887 - collected by Liloa Dunn in 2003
• 041582 - collected by Mary Umehara in 2004
• 041583 - collected by Mary Umehara in 2004
• 042529 - collected by Hank Oppenheimer in 2004
• 043483 - collected by Francisca Sohl in 2004
• 043455 - collected by Francisca Sohl in 2004
• 054701 - collected by Relio Lengsi in 2006
• 085945 - collected by David E. Brussell in 2008
• 050158 - collected by Hank Oppenheimer in 2008
• 049337 - collected by Hank Oppenheimer in 2009