Almost 60 years ago, Berg proposed that floral integration and pollination system should be associated as a consequence of the selective pressures promoting successful cross-pollination. Evidence, however, suggests instead an association between floral integration and mating system.
Fornoni et al. use a phylogenetically informed meta-analysis to show outcrossing species have lower floral integration than selfing species due to higher integration of sexual organs than perianth traits. Accordingly, the evolution of selfing seems to be associated with changes in intra-floral integration of sexual traits, thus suggesting that this complex attribute should be considered as a critical component of the selfing syndrome.
Juan Fornoni, Mariano Ordano, Rubén Pérez-Ishiwara, Karina Boege, César A. Domínguez, 2015, 'A comparison of floral integration between selfing and outcrossing species: a meta-analysis', Annals of Botany, p. mcv166 http://dx.doi.org/10.1093/aob/mcv166