Has anyone seen a potato plant start forming potatoes aboveground? They’re where each branch joins. This is a single plant from potatoes I kept myself a few years, original type BIM (dark purple skin and marbled purple flesh). Not happening on any others or in previous years.
The plant didn’t make flowers, and wasn’t buried or anything strange.
This is an interesting observation! Seems like the genetic program to make tubers has gone into overdrive, although aerial parts are likely to develop a lot of solanine (like light-exposed in-ground tubers) so they may be bitter and toxic. This might be due to a stress response, a spontaneous mutation, or perhaps a pathogen infection. It will be interesting to hear what others think.
You might try detaching a few of those growths and see if they will establish separate plants on their own (there is probably enough season left for a harvest). Maybe you have already started that. 
Please update when you dig the tubers and let us know how they turn out. Thanks for sharing!
Potatoes are modified stems, not roots, so when potato plants try to push out new stems, they usually make funky aerial potatos. As said earlier, this is usually caused by some sort of environmental stress factor, but I imagine if you were to top a potato plant, this could also happen. If you grow them in really shallow mediums, this sometimes happen as well.
Aboveground potatoes are almost always toxic.
Wow what is toxic about/in them?
When a potato is exposed to sunlight, it starts to go into overdrive in creating a toxin within itself called solanine. Solanine is a toxic glycoalkaloid that’s found in potatoes. Although they always have it, sunlight makes them produce it to toxic levels. The toxin acts as a natural pesticide, protecting the plant from insects, fungi, and us lol. That’s why they say don’t eat green potatoes. Usually the greening is a sign of high levels of solanine from being exposed to too much sun
Thanks! I assumed they’d be full of solanine. I think I dug some potatoes early right next door to it, probably the source of stress. Super interesting to hear that potatoes are modified stems.
Note that potatoes are always poisonous to eat raw, as is all the green leaves and such. Solanine breaks down when cooked and regularly grown potatoes don’t have alot in them to begin with, but of you ate a bunch raw you could get pretty sick. Same with unripe tomatoes.
When we were growing up we often ate raw sliced potatoes with a touch of salt. No one ever got sick from it so I have to disagree. If they were grown above ground and the interior is green then they are poisonous IMO
