This Campanula was collected in Russia at Karachayevo-Cherkessiya, Terbeda, Gonachkir Valley at 1800 meters so next time you are there, keep an eye peeled for it. This potentially can reach 3'-5' tall in flower with nice heads of pale lavender to white flowers in midsummer. Is it hardy, you ask? Da!
From Wendy Perry of Bosvigo Plants in S. England comes this unfortunately scarce and choice Campanula. Gently and very controllably spreading to make an impressive clump with spires of pure white flowers. Pairs impeccably with Hosta 'Patriot'.
Gawen Bellflower. A fine choice for cottage gardens or your basic flower bed, this very hardy perennal will provide a refreshing and cooling display of large cup and saucer double white flowers in early to mid summer. This is a mat-forming plant so in a few years you will have an enviable stand of flower stems you can cut for dinner parties.
Campanula punctata conjurs visions of Mongol hordes sweeping across the Tartar plains of what once was your garden. Granted this is a good spreader but certainly not the 'Cherry Bells' version of Sherman's March on Atlanta. One third size and spread but full size huge white bell flowers.