They are spelling it parnissica, but I have never heard of this. It does not seem to be listed anywhere. I wonder if someone has badly mis-spelled pratensis?

I wonder if Christian Froissart has heard of it. Is it a new species from Greece? S. parnassica?

I found a hit on Pleoger de bilt for Salvia parnassica. It must be new. There are both a Nepeta parnassica and a Satureia parnassica species

You could be right indeed. No words about Salvia parnassica in the book of Froissard.
I have asked informations to the HPS and to the nursery Ploeger de bilt. I shall tell you if answers.
Many thanks for your help.

I have received an answer from the nursery Ploeger de bilt.
Their plants come from seeds found on plants growing in the mountains in Tschechie.

I have got two plants from my seeds. Good result indeed because the seeds looked like dust...