Fellow allotmenteers kept insisting that this purple spiky head plant that is also affectionately known as Partick Thistle in the West of Scotland was a Globe artichoke, but I had my doubts whether it was actually a globe artichoke. It was far more jaggedy. Then a good eight months later, I found out directly by the person who had given the plant to my plots original owner, that it was in fact a cardoon, not a globe artichoke.
Cardoon is a close relative of the globe artichoke, so you can understand the confusion, but the Cardoons head which resembles the globe artichoke is not edible. The edible part of the cardoon is its stalk, when stripped and cooked. I had not done much to the cardoon, other than let passers by touch its prickly head and admire it.
But now while its winter and in it's dormant state. I have parted the one plant into 6 and have replanted them in a nice neat line. Hopefully they will be okay, grow and be even more dramatic and welcoming to the eye. We shall have to wait till the summer to see.