Question
Hi Tom,
I just opened an Organic Navel Orange I bought at a local Kroger store.  To my amazement and surprise I found a seed inside, just one.
And so I was wondering: How does that happen?
It didn't seem to have a second orange growing at the end, maybe the seed instead.
2nd question: Is this then a seed or a dead/not developed secondary orange? It really looks like a seed.
Have you ever seen this? heard of it? or understand it? Do you think it will grow?

Thanks!
- Will J.
 Denver, CO

Answer
Hi Will,
Thanx for your question. Not being an expert on citrus, I am going to wing it based on information I've gleaned over the years on genetics.

A navel orange is a hybrid.  On occasions, hybrids will throw back to a prior generation and exhibit a characteristic that has been bred out such as the production of seeds.  Even though the characteristic may have been 'bred out', there remains a recessive gene that may surface depending upon some kind of mutation.  Your situation sounds to me like a mutation and not likely to occur again, anytime soon.

A lot of mutations are sterile but you can plant the seed and if it doesn't germinate after a month in a warm, damp environment, it probably is sterile.  If not, it will germinate and develop into a plant that most likely will NOT completely resemble the parent plant.  It will most likely be inferior, meaning the fruit might be seedy, less sweet mature later, etc.  Hybrids are not genetically stable and do not produce seed that are consistent in results.

We often see mutations in our world or genetic hybrids.  Practically all fruit in the market unless indicated otherwise, are fruit of genetic hybrids and their seeds will not come true to the parent plants.  That doesn't mean their progeny will not be desirable.  I have a friend who grew a peach tree from seed and the peaches are perfectly acceptable and edible.

I hope this helps.
Tom