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| Female papaya tree with fruit |
The St. Lucian workmen laughed when they saw our handsome
papaya tree.
"That pawpaw is the wrong sex. You’ll never get any fruit
from that one."
"No way to know until it grows up", they told me. "Then you
can tell by the flowers."
It seems the female flowers grow close to the stem of the
plant, where the leaves are attached. The male flowers are smaller and thinner,
and grow on stalks farther away from the stem. Sure enough, our papaya tree had
flowers drooping far out from the stem.
"Nothing to do but chop it down. It’s no good" they said. Then one of
the men suggested chopping off its head – the distinctive crown of leaves at
the top of the stem.
"Maybe that will make it turn into a female." Closer questioning produced more laughter and insinuations that maybe our papaya tree was an ‘anti-man’. Now I suspected they were just fooling with me. I had heard of fish changing sex under stressful environmental conditions, but not transsexual fruit.
The story got even more complicated when I looked up ‘papaya
sex’ on the Internet. It seems that papayas come in three sexes: male, female
and hermaphrodite. The male flowers produce pollen, but not fruit. The female
plants have ovaries that can produce fruit, but their flowers need to be
fertilized with pollen from another plant, otherwise the fruits won’t develop
and will drop off while they are still small.
The third sex - hermaphrodite papaya trees - have flowers
with ovaries as well as ones with pollen, so they can fertilize themselves
without needing a partner - or even any help from the birds and the bees. Apparently papaya
farmers prefer them because they are more dependable and produce the sweetest
fruit. Their fruit is also longer than the fruit from a female papaya tree,
which is rounder in shape.
However, although hermaphrodite papaya trees have both male
and female flowers, their yin and yang are not always exactly in balance. Some
of the hermaphrodites have more male flowers and some have more female ones -
and some flowers can actually change their sex. Warmer temperatures can make
the hermaphrodite trees produce more male flowers, whereas cool temperatures or wet soil
can make them have more female ones.
One article described efforts to do genetic testing on
papayas to try to determine the sex of seedlings without having to wait for them
to grow up. Commercial growers - or even backyard gardeners like me - don’t want to
waste their time and effort nurturing fruitless trees. Genetic mapping recently
revealed that papayas have developed specialized sex chromosomes carrying genes
that determine the sex of their offspring, remarkably like humans. But it appears that sexual identity may not
be all in the genes.
The female papaya trees were described as the most stable
ones, with clearly defined sexuality.
Some seedlings, however, were identified as ‘sexually ambivalent
males’. It turns out that it is not just
the hermaphrodite trees that are sexually unstable. Despite their sex
chromosomes, male papaya trees can also end up changing their sexual
orientation in response to seasonal changes and climate conditions.
And then I saw what I was looking for. Confirmation that the
St. Lucians weren’t just pulling my leg. “Some male trees can be induced to
change into female trees by decapitation.”
What an interesting manifestation of intelligent design. It may seem
more like the French Revolution than the Garden of Eden, but sometimes heads just have to roll.
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| Pearly-eyed thrasher eating papaya off the tree |
