Harebell, Campanula rotundifolia
 
Harebell is a delicate-looking but hardy, long-blooming plant ideal for borders, sidewalk edges, and rock gardens. It's only about 30 cm tall. The papery-looking blue flowers bloom from June to September. Deadheading can further extend the long bloom time. The plant spreads slowly by its fibrous roots and fills empty spaces by self-seeding. 
 
Ecology:
The bellflower resin bee in the picture is a frequent visitor among many small and other medium-sized bees and moths enjoying nectar and pollen from the open, easily accessible flowers.
It supports two pollen-specialist bees that rely on bellflower pollen in their larval stage. 
 
Growing Conditions:
Harebell is native to almost all of North America, including Alaska, the West, and even Greenland. It thrives in diverse habitats like cliffs, beaches, meadows, woodlands and at elevations up to 3500 meters high. It can grow in medium-moist to dry sandy, loamy or rocky soil or in almost no soil. It requires full sun to part shade.