If it does occur, protandry does nothing to prevent geitonogamous self-pollination: that is, pollination with pollen from another flower on the same plant. In fact, when birds forage at "B. prionotes", only about a quarter of all movements from inflorescence to inflorescence involve a change of plant. Geitonogamous self-pollination must therefore occur more often in this species than cross-pollination. This does not imply high rates of self-fertilisation, however, as the species appears highly self-incompatible: although pollen grains will germinate on flowers of the self plant, they apparently fail to produce pollen tubes that penetrate the style. Even where cross-pollination does occur, fertilisation rate is fairly low. It is speculated that this is related to "a variety of chemical reactions at the pollen-stigma interface".