Cambessedesia hilariana and the buzz-pollination

Many plant species have evolved floral characteristics that restrict pollen access. Some of these species are visited by insects, principally bees, which make use of vibrations to extract pollen from anthers. This phenomenon is generally known as Buzz-pollination

Like the majority of the species of the family Melastomataceae (Myrtales), Cambessedesia hilariana have flowers with rich colors and poricidal anthers (the dehiscence or pollen release occurs through a small hole or pore). In this species, endemic to Brazil, the flowers, measuring about 15-17 mm in diameter, have yellow petals with the tip orange. This type of color is one of the important attributes related to attraction to bees. These flowers are classified as melittophilous, it is that they are visited and pollinated almost exclusively by diurnal bees that buzz the anthers to release their pollen. 

A study of pollination and the reproductive systems of Cambessedesia hilariana, showed that large, diurnal bees of the genera Centris, Bombus, and Xylocopa are the principal pollinators.

It is considered that the evolution of buzz-pollination was likely triggered by the necessity of nectarless plants to restrict pollen access, reducing gamete loss to inefficient pollinators and pollen thieves, that is, visitors that remove pollen with little or no contribution to deposition on stigmas, and maximizing pollen dispersal to conspecific plants. Poricidal anthers may exclude some visitors (pollen eating beetles, flies, and non-buzzing bees), and could also act as a pollen-dispensing mechanism to maximize pollen export by legitimate buzz-pollinators.

References: [1] - [2] - [3]

Photo credits: [Top: ©Maria/Amethist | Locality: Delfinopolis, Minas Gerais, Brazil, 2011] - [Bottom: ©Ivan Abreu | Locality: Arapiranga, Rio de Contas, Bahia, Brazil, 2009]