Strongly oligolectic on Campanula (Campanulaceae)(Pesenko in Banaszak, 1995; Stanisavljević, 2000; Westrich, 1989). Known pollen sources include: Campanula rotundifolia, Campanula trachelium, Campanula persicifolia, Campanula glomerata, Campanula poscharskyana, Campanula isophylla (Westrich, 1989).
Pawlikowski & Kruszynski (1997) list Campanula rotundifolia (Campanulaceae) as a forage source in Poland.
Pekkarinen (1998) lists only Campanula (Campanulaceae) as a pollen source in Finland.
Ivanov et al (2005) state that the species is monolectic on Campanula (Campanulaceae) but such a designation must be an error.
Praz et al (2008) list Campanula rotundifolia and Campanula portenschlagiana (Campanulaceae) as pollen forage plants.
The species epithet “rapunculi” and the vernacular name “Hériade de la raiponce” both given by Lepeletier (1841) refer to Phyteuma, suggesting that flowers of this Campanulaceae genus might occasionally be exploited by C. rapunculi in addition to Campanula.