Abstract
Heteranthery has always aroused interest regarding its functionality. Desmocelis villosa (Melastomataceae) has flowers with dimorphic stamens, one group being composed of five yellow anthers and the other of five purple anthers. The current study assessed whether heteranthery promotes division of labor in this species. An experiment was performed with removal of anthers of each type in order to compare the visitation rate by bees. On vibrating the set of stamens, bees collected pollen from the yellow anthers, while the purple anthers deposited their pollen on the end part of their bodies in a position close to the stigma, thus allowing pollination. Flowers with yellow anthers showed higher visitation rates than those that solely had purple anthers. In this species, heteranthery is found to be an effective strategy for economizing pollen, which is used as a floral reward, given that, although the two types of anthers show a high percentage of viable grains, the yellow anthers have significantly fewer pollen grains than the purple ones, indicating that the plant strategically reserves most of the pollen for sexual reproduction purposes.
Key words:
stamen dimorphism; division of labour; functional specialization; buzz pollination
