A monotypic genus, an annual or biennial herb, of e. and c. North America. Shetler & Morin (1986) stated that "Small's view [segregating Campanula americana into the monotypic genus Campanulastrum] appears to have increasing justification from palynological, cytological, and now seed evidence". Campanulastrum was also supported as a genus by Shulkina, Gaskin, & Eddie (2003), but combined into Campanula by Lammers in Kadereit & Jeffrey (2007) and Roquet et al. (2008). Molecular and morphological evidence shows Campanulastrum as more closely related to Triodanis and Legousia than to Campanula s.s., and so needs recognition at genus rank if the course followed in this flora is to be taken (recognizing monophyletic segregate genera, as opposed to expanding Campanula further) (see Morin 2020).
Ref: Crowl et al. (2014); Kadereit & Jeffrey (2007); Mansion et al. (2012); Morin (2020); Roquet et al. (2008); Rosatti (1986); Shetler & Morin (1986); Shulkina, Gaskin, & Eddie (2003). Show full citations.