Petrocodon is a diverse and formerly small genus with a limited number of species. Recent genetic analysis reported by Weber et al (2011) have refined our understanding of relationships within a related group of Chinese gesneriads.  This has resulted in the transfer of several species from multiple other genera into Petrocodon, for a total of around 20 species.

Few of these species have been in cultivation, with the notable exception of the former Calcareoboea coccinea, now properly Petrocodon coccineus.