When you buy a banana at the store, it doesn't seem to contain any seeds. How does the banana tree reproduce, then?
If you went out into the wild and opened a banana fruit, you would probably find seeds. Some, in fact, are large and take up much of the fruit, making the flesh hard to eat. Our commercial bananas (which are, for the most part, the Cavendish variety) have been specially bred over the years so that they are seedless triploids (three sets of genes, instead of just two) that do not form mature seeds. If you've noticed little black dots in the middle of the banana, you've discovered immature seeds that won't develop, which happens with triploids.
Instead of using seeds, commercial banana trees are reproduced by using banana pups. The banana tree forms rhizomes that form into a little tree known as a pup that can be removed and planted elsewhere.