Towards a resolution of the 'Campanula problem'

The genus Campanula comprises over 400 species but there is little agreement about generic boundaries within the subfamily Campanuloideae or the infrageneric classification of Campanula itself. Many monotypic or oligotypic genera are recognised while other students prefer to merge these with Campanula. Both treatments have advantages and disadvantages and a balanced approach is required. We suggest that the merging of genera leads to a general loss of evolutionary insight and the appreciation of the evolutionary and ecological uniqueness. Conversely, the recognition of numerous mono- and oligotypic genera is disadvantageous for general use, particularly for gardeners and horticulturalists. Cladistic analyses, while useful for determining phylogenetic relationships, are detrimental to the construction of a workable classification, if not used with caution. It is recommended that traditional morphological characters, supplemented by ecological, biogeographic and other data sets, and guided by findings from molecular data, should allow a reclassification of Campanula to be achieved, especially if paraphyletic taxa are recognised. Several shortcomings to our present knowledge are listed and possible novel approaches for future investigation are suggested.