Data were collected to determine the geographic distribution of different cytotypes of Campanula rotundifolia L. Most sampling concentrated on Britain and Ireland, but samples from mainland Europe, the Russian Federation and North America were also analysed. Following these observations, a common garden study of tetraploid, pentaploid and hexaploid cytotypes representative of Britain and Ireland was set up at a CEH Edinburgh (where the local cytotype is tetraploid), to determine whether climatic factors were limiting the distribution of the hexaploid cytotype through effects on growth, survival or flowering phenology. The geographic distribution study ran from 2006-2019. The common garden study ran from 2008-2010.