Blue/purple potatoes going green?

[BarleySugar]

I don't know if anyone can help, but I bought some violette potatoes from T&M this year as a novelty. They have been very slow growing, and the yield isn't great, but they taste good, and look weird. Anyway, I dug the rest today, and I noticed they have a strange growing habit, despite being earthed up the bines still seemed to be growing along the top of the ground, and making tubers at intervals. Due to the colour it seems virtually impossible to see if there is any greening of the tubers. I know that greening indicates that poisonous solanine can be present, and apparently it gives a bitter taste. Has anyone grown these potatoes, and know if it is possible to detact a green colour if they are exposed to light? I supposed I could leave one in the light for a while, to see if I could detect greening, but I'd really like to eat them now, rather than waiting for the result of an experiment.

[Two_Sheds]

the bines still seemed to be growing along the top of the ground, and making tubers at intervals.

Bines ???

I've just dug up some Mr Little's (purple) and noticed a strange thing too, which I was going to post. The normal tubers were underground, but small shiny tubers had started to appear up the stems too, above ground.
These have shooted with tiny green leaves so I'm going to pot them up and try to keep them alive indoors over winter.

Photo to follow

[Thelma Sanders]

but small shiny tubers had started to appear up the stems too, above ground.

Do they look like green tomatoes? cos these are just seed potato seed pods.

is possible to detact a green colour if they are exposed to light?

Peel one thinly and you'll see if there is green under the surface, or not ;

[BarleySugar]

Sorry, I know the proper term used is haulms, but I was tired, and used the word my dad always called them without thinking.
Peeling these potatoes wouldn't help they are purple right through, and stay purple when cooked. Anyway we had some with dinner tonight, and they weren't bitter. I should have used gloves through. I scrubbed them well as they are too knobbly to peel without losing almost all the potato. My fingers and the water turned purple. Quite pretty really.

[Two_Sheds]

Photo to follow

Here 'tis

Do they look like green tomatoes? cos these are just seed potato seed pods.

Yep, I know

These are proper little tiny potatoes, but are growing on the stem above ground, and they've started to sprout leaves too

[Plot103]

I am sure I read somewhere that aerial tubers can just be the result of stem damage (so not a problem) but it is also one of the possible symptoms of Black Scurf.

Potato black scurf and stem canker / Royal Horticultural Society

[Two_Sheds]

Interesting link ^, but there's no sign of any kind of disease or damage on the plants, they're very healthy