Scanning electron microscopy (SEM) image of individual pollen grains (outcrosser) showing the surface of the pollen coat. Credit: Luciana Salomon In flowering plants, the transition from cross-fertilization (outcrossing) to self-fertilization has evolved repeatedly across species. This shift is often accompanied by a well-known set of traits collectively called the "selfing syndrome," including smaller flowers and reduced scent. However, a new study highlights that important but largely overlooked changes also occur at the microscopic level of pollen biology. Researchers from the Faculty of Science at Charles University and The Institute of Experimental Botany of the Czech Academy of Sciences (IEB) investigated how self-fertilization affects the pollen coat, a thin outer layer of pollen grains that plays a crucial role in successful reproduction, particularly in interactions between pollen and the female reproductive organs.…