Flowers are under selection by both pollinators and also non-pollinator agents, which include the physiological costs of building and maintaining flowers. These agents of selection often oppose each other. In this paper, I used an energy balance model to estimate how traits under pollinator selection may influence flower energy balance and how variation in hydraulic traits may be able to compensate for thermal effects due to pollinator selection.
The full text is freely available through the International Journal of Plant Sciences. One of the images of a Calycanthus tepal I took using the SEM at the Arnold Arboretum is featured on the cover: