I have a bunch of popcorn growing in my back yard, and as I was harvesting it, I found an ear with completely white kernels. There was absolutely no color whatsoever, but the seeds were fully developed. The rest of the popcorn is dark red, and it all comes from the same packet of seeds. The cob was also white instead of pink like the rest. What causes this? How common is it?
What causes it is a lack of pigment. What causes that is either the loss of a gene necesary to making pigment, or a mutation that disrupts the production of the pigment. Like you said, it’s albino corn - just like other living things can lose pigment.
you might try saving some of those seeds and planting them next year for more albino corn.
There are all kinds of colour varieties - some of them are wholly white, others have a mixture of any or all of yellow, white, red, black and blue kernels.
If you planted the stuff from seed (as opposed to buying trays of seedlings), you’d have noticed a different coloured seed when you planted it, in which case it could be a ‘sport’ - a spontaneous mutation, or it could just be that the parent plant happened to receive a stray pollen grain from a white variety growing nearby - it would still develop into a red seed (as determined by the physiology of the female parent plant), but would contain genes from the white male parent.
Sorry, that wasn’t particularly clear; what I was trying to say is that normally, the most likely cause for this sort of thing is that a stray seed from a different variety gets mixed in somewhere along the line, but if you planted the things from seed and all the seeds were red, then the cause is either spontaneous mutation or mixed parentage.