I have not found Swiss wallflower seeds or plants.
But I have found a candidate in my own back yard almost.
Erysimum arenicola also called Erysimum torulosum?
Cascade wallflower after the mountains in Washington and B.C.
Found seeds at Plant World Seeds in UK.
This may be a hardy yellow wallflower.
I tried Erysimum Perskovskii but it is too weedy looking.
