Aerial Tubers, not Potato Berries

Q: I found three pink, thumb-sized things growing 6 inches above ground, attached to my potato plant. I don’t think they are potato berries because they are hard like a potato. They don’t appear to be potatoes because potatoes exposed to sunlight turn green. I am stumped because I’ve never run across something like this before. 

A: A berry is the seeds and flesh left when a flower fades, so you do not have a berry. What you have are aerial tubers, actual potatoes which sometimes form at wounds on the stem. Injuries break the phloem tubes in the stem. The sugars produced by the leaves have no place to go, so the plant forms aerial tubers as a storage site. They can be planted and will sprout, but don’t be tempted to eat one because high glycoalkaloid content from exposure to the sun, even under a pink skin, makes them toxic.