Flowers of Neotropical Malpighiaceae have a specialized pollination system in which floral oils instead of nectar are offered to attract oil-collecting bees. Cappellari et al. examine facultative loss of oil production by non-oil-secreting (eglandular) flowers in relation to pollination by bumblebees in populations of Pterandra pyroidea from the Brazilian Cerrado. They find that eglandular flowers represent a shift in the pollination system in which oil is being lost and pollen is becoming the main reward. This species thus exhibits an unusual transition from a specialized towards a generalized pollination system.