Yvonne & Techo, please forget everything what I told you about this plant. Today, I visited our botanic garden and found out it is Eryngium giganteum; English names are Miss Willmott's Ghost or Giant Sea Holly.
Teasel and Giant Sea Holly are of the same botanic class (magnoliopsida) but belong to different orders--but does really anybody want to know these details?
Without your question I probably never would have known exactly what I have photographed ;-)
Nice topic btw.
Gerald
Yvonne and Techo, thanks for your comments. This is some kind of teasel (Dipsacus in Latin). I have googled for more information as I am not very good in botany and was able to find out that the most common subspecies is Fuller's Teasel, which is growing in the wild in Europe, but it would not have these spiky collars. I have seen this kind nowhere else but in botanic gardens; unfortunately, I cannot remember what was written on the sign.
Gerald