Campanula pulla

Campanula pulla, the solitary harebell, is a species of flowering plant in the family Campanulaceae, native to the northeastern Alps of Austria.
A spreading, mat-forming perennial, the Royal Horticultural Society recommends it for scree gardens. It is available from commercial suppliers. There appear to be cultivars or selections; 'Blue Drops' and 'Alba', and a hybrid with Campanula carpatica; Campanula × pulloides, which itself has cultivars, 'Jelly Bells', and 'G.F. Wilson', which has gained the RHS Award of Garden Merit.