Re: Where are the seeds in a pineapple plant?

Dear Barbara,

Pineapples are native to South America.  About the only place you will find 
a pineapple with viable seeds is in South America on a naturally growing 
pineapple plant.  A pineapple develops from multiple flowers.  There are 
many thick, hard floral bracts or leaf-like petals on the outside of a 
pineapple.  If you did find a pineapple with seeds, it would contain one 
seed for each flower that produced the pineapple.

It is difficult to find seeds in commercially grown pineapples.  Commercial 
pineapples have been selected for their vestigial seeds (the same is true 
for bananas).  Commercial pineapples are propagated by planting a 
vegetative part of the plant (the stalk, the tufts at the top of the fruit 
or the tufts at the bottom of the fruit).  They are not grown from seeds.

Robert Houska

Mad Scientist

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Admin note:
David Hershey adds the following:

Pineapples are pollinated by hummingbirds and are self-sterile, meaning
they cannot produce seeds if they pollinate themselves (self-pollination).
To get seeds, pineapples must be cross-pollinated. Cross pollination is
prevented in two ways. First, the importation of hummingbirds is banned in
Hawaii where many pineapples are grown commercially. Second, all the
pineapples in one field are genetically the same, so that if pollen is
transferred from one plant to another, it is still self-pollination. Cross
pollination requires that the plant providing the pollen is genetically
different from the plant receiving the pollen. Cultivated pineapples would
produce seeds if they were cross-pollinated. However, a seedy pineapple
fruit would be very undesirable because it would contain hundreds of hard
seeds so growers make sure that they are not cross-pollinated. Collins
(1960) says eating a seedy pineapple is like eating a normal pineapple
containing a thousand tiny bits of gravel.

Pineapple fruit development is an example of parthenocarpy or development
of fruits without seeds. In nature, this may be an advantage to the
pineapple in two ways. First, the leafy crown at the top of a pineapple
fruit can root and produce another plant, so even without seeds a
pineapple fruit can reproduce the plant. Second, a seedless fruit may
provide food for the animals that normally disseminate the seeds. This
could prevent the animals from starving or migrating in years when few
flowers are successfully cross-pollinated and seeds produced. Also, the
seedless fruit of the pineapple makes it a very desirable food for people
so we grow thousands of acres of pineapples. Many of our most popular
fruits are seedless, such as bananas, seedless grapes, naval oranges,
seedless grapefruit, seedless watermelon and certain types of figs and
persimmons.

David Hershey

References:

Samson, J.A. 1986. Tropical Fruits. New York: Longman.

Collins, J.C. 1960. The Pineapple. New York: Interscience.