Male papaya flowers are disgusting

Most plants are monoecious, i.e. they make hermaphroditic flowers carrying both female (pistil) and male parts (stamens). In papaya the flowers may have different genders (dioecious).

A male papaya tree is not good for the farmer who wants delicious fruit from female flowers. The Seehamongkol family considers a male to be ‘another variety’ and they simply cut it down. I read that some people eat the male flowers, and so I asked Nived to cook them. She said nobody eats them, and she said she had never seen them for sale anywhere in Thailand. I insisted, and although Nived boiled the flowers before stir-frying, they were terribly bitter! Although the Seehamongkol family enjoys equally bitter gall bladder, neem leaves and midnight horror fruits, these flowers were disgusting even to them.

If any of our readers know how to cook male papaya flowers, or which cultivar to select, please share with us! Update on October 27th: Recently Aini Zakaria from Malaysia, a soil scientist and a former student at Lund University, explained that in Malaysia they cook the male flowers of papaya together with leaves of Malabar blackmouth (Melastoma malabathricum) 1:1, and then they discard the water and the black mouth’s leaves. The purpose is to make the flowers less bitter. This morning we tried her recipe (boiling for 30 minutes) and it works! Ketsanee and I are most grateful.

Male flowers have only stamens and can not make fruit. Even from a distance you can tell they are male, because they form in clusters on long flexible stalks. The rule is not absolute, sometimes you get female flowers intermixed.

According to one visitor to Dokmai Garden one can change a papaya male to become a female by damaging the tree, such as carving a cross. Theoretically the stress induces a hormonal change aimed at making fruits and seeds, ultimately the papaya tries to escape this poor place where you apparently get stabbed. If this works or not is something I wish to see with my own eyes. However, if nothing happens you may argue the stress (the carving) was not severe enough, and if something do happen you may argue it might have happened of other reasons. To scientifically test this technique, you need at least 50 males of each treatment. However, a small scale test is a pilot study to give you a hunch.

Perfect fruits from female flowers formed in the leaf axils near the stem. These fruits indeed look ‘feminine’, like breasts full of milk.

Why would a papaya tree make male flowers in the first place? Male pollen fertilizing female flowers (sex) cause a recombination of genes. The greater the genetic diversity among the seeds, the greater the chances some offspring will survive an ever-changing world. One alternative is cloning, creating identical offspring, which is risky if the environment changes. Another alternative is self recombination, but that constitutes less variety than in sexual reproduction.

A female papaya do not need pollen, she can make fruits anyhow. Interestingly, papaya can also make hermaphroditic flowers. One type has a round ovary and makes round fruits, one has an elongated ovary and makes peculiar long fruits. Some home gardeners believe that these odd-looking fruits are due to some disease, but it is just normal variation.

An elongated fruit from a hermaphroditic flower.

Sections of three flower types of three different papaya plants originating from the same batch of seeds. To the left a female flower with its massive ovary, branched stigma and absence of yellow male pollen-carrying anthers. In the middle a hermaphrodite with female-like long petals but presence of yellow male anthers and a tiny ovary with an unbranched stigma. To the right a male flower with its typical long tube, small petals, yellow anthers and a reduced female organ.

In spite of ‘papaya salad’ being a national Thai dish, papaya is not even native to Asia. It originates in Central America. There are 23 species of Papaya but only one is commonly grown: Carica papaya (Caricaceae). The ancestors of our domesticated papaya are not known. A wonderful feature of papaya is that it fruits all year round. I like to serve it cold, then it is like ice cream. Be aware that some varieties are much better than others.

If the fruit is soft, then it is sweet and ripe, regardless whether it is green or not. Picture from the book ‘Fruits and vegetables in Southeast Asian markets’.

Warning! The papaya ringspot virus is a terrible disease and you must cut any tree with symptoms immediately! This virus is particularly common in Chiang Mai. It is not dangerous to humans but will distort leaves and fruits. The virus is spread via sucking insect such as aphids. Do not buy little seedlings at the Khamtieng flower market (like we did). Instead, take a look at your neighbour’s papaya tree. If it looks fine, buy a ripe fruit and taste it. If it is good, then plant the seeds.

When cutting down a papaya you realize the stem is soft (more herb-like than woody) and even hollow at the base. The stem is so soft you can not build anything from it, and it deteriorates quickly after logging. Feed it to the pigs, and use the leaves for wrapping and tenderizing meat; the enzyme papain degrades protein.

Papaya is easy to grow in Chiang Mai, but water logging will kill it. You will get your first fruits quickly after planting a seedling, usually within months.

Text: Eric Danell

Photo: All pictures were taken at Dokmai Garden in Chiang Mai. Jussi Suominen took the picture of the viral leaves, the other photos except the cut fruit were taken by Eric Danell on August 29th, 2012.