I first got seed of Campanula trogerae from Jim and Jenny Archibald almost 20 years ago: it has thrived ever since then. In fact, I think my original plants are still growing in my first home garden to this day. They bloom from late June almost to August, in the very heart of the summer: surely among the largest flowered, and most crystalline blooms in the genus. Of course, instead of bell shaped these are this strange, starry shape reminiscent of Michauxia...come to think of it, Michauxia does grow thereabouts. Perhaps there was some ancient hanky panky with C. betulifolia responsible for this anomalous flower?
I can't imagine my gardens without this most spectacular plant in the genus. Easy to grow.