Interesting - bit of genetic confusion there, lol! Is that the only deformation on the plant, or are there more?

As Clematis don't technically have petals but tepals (closer to leaves than true petals) they do sometimes do this especially if there has been some physiological stress during the buds very early development 6-8weeks previously which would ring true.

That would also explain the torsion of the leaf, I guess, which is often temperature related.

Bamboo - no, there are no other deformations. On the whole, it's always been a very healthy specimin. At least 8 years old now. Thanks for that though.

Sorry - I meant specimen!!!! Shame on me - I've always prided myself on my spelling.

Well you're not alone with the spelling thing - I'm a brilliant speller, but typos creep in all the time, especially when I'm in a hurry, usually on the little words! Nothing to worry about on your plant, it's just a curiosity, not a disease.

There is bound to be some distortion on that leaf, anyway, with parts trying to be a tepal, and parts trying to be a leaf--two completely different sizes and shapes. Just a slight "mistake" on the plant's part.

I wonder what it says about me that I'm comforted by a plant's fallibility?

We all are I'd imagine, Tugbrethil!