Flowers of extant Quintinia are described in detail on the basis of field observations and serial microtome sections and compared with flowers of the Late Cretaceous Silvianthemum suecicum and Bertilanthus scanicus on the basis of new analyses of the fossil material. The analyses of both extant and fossil material also include synchrotron-based X-ray tomographic microscopy. The study shows that Quintinia and Silvianthemum/Bertilanthus have more features in common than previously recognized and strongly reinforces their earlier assumed close relationships. Among important characters linking the three genera are similar secretory hairs on the floral surface and pedicel; short sepals; free, quincuncial petals; broad anthers with small pollen sacs; 4-aperturate pollen (in Silvianthemum and Quintinia); postgenital union of the 3–4 apocarpous styles (in Silvianthemum and Quintinia); connection of the apocarpous carpel parts with the floral base; downward tapering ovary and locule(s); placentation on incomplete septa; and flask-shaped epidermal cells with a thin and long papilla on the carpels. Features observed in Quintinia, particularly the presence of bitegmic ovules and free petals, suggest that the apparent phylogenetic position with extant Paracryphiales (campanulids) needs further analysis. Bitegmic ovules are not known from other Paracryphiales or campanulids, and the presence of free petals is unusual in campanulids.