Influência dos atributos florais de pleroma granulosum (desr.) D. Don (melastomataceae) na liberação dos grãos de pólen

Abstract

Approximately twenty thousand angiosperm species offer only pollen as a reward to pollinators, and their flowers are known as "pollen flowers." This creates an evolutionary dilemma, as pollen serves both as a resource offered to pollinators and as the vehicle for the plant's male gametes. One solution to this dilemma is heteranthery, a trait where the plant develops stamens with different functions, including how pollen is made available to visitors. Heteranthery is common in the Melastomataceae family, whose flowers are often pollinated by bees capable of vibrating their wing muscles to release pollen grains, in a process known as "buzz pollination." However, beyond heteranthery itself, little is known about how other morphological attributes of these flowers affect pollen release. Thus, this study aimed to understand which morphological characteristics of the stamens influence pollen release in Pleroma granulosum. To achieve this, artificial vibrations were used to remove pollen from the stamens of P. granulosum. There is a correlation between the size and shape of the stamens, with larger stamens exhibiting distinct morphology compared to smaller ones. Pore area proved to be an important variable in controlling pollen release, although, counterintuitively, there appears to be an optimal pore size for maximizing release. Our findings contribute to a better understanding of the morphological adaptations that may favor efficient pollen release in Melastomataceae. Future studies could more broadly explore the relationship between vibrational properties and morphological characteristics of stamens in different species of this family, deepening our understanding of the evolution of pollination mechanisms in these plants.