Thus, the pollination biology of P. royenii contradicts the hy- pothesis that Neotropical chiropterophilous cacti are strictly polli- nated by bats. In addition, pollinating activity of carpenter bees may be affecting variation in floral characteristics. Our data and that of others suggest that the chiropterophilous pollination syndrome in columnar cacti appears to break down in extratropical regions and islands subjected to periodic, severe disturbances.