Peter, I decided a while back to spend more time working with the unusual forms in the semp world. I set out to acquire as many of the unusual forms as I could, including those that have a reputation for throwing crests. So I have a few in my collection to track. I agree with your nomenclature regarding S. 'Bedivere Crested'. I follow the same convention with regard to the crests I have.
So far, the following have crested for me and I have viable, but not yet stable, crested plants growing. Sopa and Deep Fire have produced offsets this year. Deep Fire's offsets appear normal, but the Sopa offset is itself crested.
S. Sopa
S. Borimere
S. Deep Fire
S. Mauna Kea
I also have Fuzzy Wuzzy, known to crest, in my collection but so far is has remained normal. My Mauna Kea normal produces a couple of crested plants each year so far. Most of them do not survive long, so last year I started transplanting them so that I could provide more attention.
Do you have/know of a list of the varieties known to produce crests? I'm trying to get Weirdo and Whirl-i-gig added to the my unusual forms collection but they are hard to come by here.
Fascinating topic and thanks for starting the thread.
Sempervivum Sopa Crested w crested offset
