Uli,
I just received an offer of seed from a friend down under (his plants are flowering right now) seed derived from the Goteborg.
Pictures of his plants do not exhibit the pronounced purple calyx---I am sure there is natural variation but he queried whether this might happen due to the mild weather. My instinct is "no".
I wonder if you could post a picture of your specimen, showing the purple calyx, if you have one?
Would you say that his plants, as posted here are the correct species?
Thank You,
Kristl