Pulsatilla grandis   (P. vulgaris ssp. grandis or P. halleri ssp. grandis) is a native of Hungary and surrounding countries in central Europe, and as far north as Gotland, on limestone areas. The flowers are of a blue to violet colour (the pale blue 'Budapest' is described elsewhere on this website). In truth, the exact status of this species and its relationships to P.vulgaris and P.halleri seem to be complex and Christopher Grey-Wilson devotes a whole page in his monograph to discussing these !

I bought this as a flowering plant, and then after a tidy in the autumn it overwintered out in the garden under a bench for shelter. (It requires good drainage and benefits from protection from winter rain in this climate.)