Floral scents, leaf volatiles and thermogenic flowers in Magnoliaceae

The role and chemical composition of floral scent in pollination systems of angiosperms has been largely ignored because of the difficulty in characterizing scent components. Magnoliaceae is one of the few plant families in which the floral scents of a large number of species have been analyzed. Within the family, floral scents of taxa are dominated by one chemical class of compounds (e.g. benzenoids or terpenoids etc.). Artificially damaged leaves emit a variety of chemicals, some of which also occur in the floral scents (e.g. 4,8‐dimethyl‐1,3( E ),7‐nonatriene, linalool etc.). Floral thermogenesis occurs in Magnoliaceae and enhances evaporation of floral scent (in Magnolia tamaulipana A. Vázquez, sp. nov.) and may serve as a direct energy reward to visiting insects. It is hypothesized that floral heat and scent may have been key components in the breeding systems of early angiosperms. Floral heat may have been a major resource for insects and one that could be provided by plants without evolution of elaborate morphological features. In this regard, fragrance signals not only food and mating sites, but also heat.