Could a “hot” flower attract pollinators by serving as a reward in a plant-pollinator mutualism? Many flowering plants produce nectar and pollen as rewards in exchange for pollination services by insects and other animals. Interestingly, however, a few plants have flowers that also produce heat metabolically — so what is the adaptive function of this flower heating?
Susanne Renner from the University of Munich, Germany and Shi-Xiao Luo from the South China Botanical Garden, along with collaborators from China and Taiwan, were interested in determining whether there was a connection between the heating of flowers and the pollination services of flies in an ancient Chinese family, Schisandraceae. Although this family is quite widespread, including Asia and the Americas, its center of diversity is in China, which is one reason Renner and colleagues chose to examine this question in two Chinese Illicium species. Their novel findings are published in the July issue of the American Journal of Botany.
“A few flowers, usually ones pollinated by beetles or flies, produce heat to help scent emission or to create especially attractive egg laying sites for their pollinators,” Renner commented. “Usually such heating occurs only during flowering, simultaneous with the release of pollen and stigma receptivity. We discovered that in an Asian Illicium species, flowers reach their highest temperatures during early fruit development, and experiments revealed that this is for the exclusive benefit of the pollinator’s larvae, which develop in the spent flowers.” Read more, When flowers turn up the heat