Among the 416 angiosperm families, palms (Arecaceae) are striking in possessing almost all possible combinations of hermaphroditic and/or unisexual flowers, making them a particularly interesting subject for studies of the evolution of plant sexuality. The purpose of this review is to highlight the amazing diversity of sexual expression in palms with a view to proposing scenarios to explain the evolution of this character, drawing on the numerous advances that have been made over the last 20 years in palm systematics, ecology, developmental biology, phylogenetics and genomics. We provide an overview of the variability of sexual expression in palms, with illustrations of the associated morphological diversity and its significance to reproduction. We discuss the evolution of sexual systems using the most recent phylogenetic framework available for palms. Finally, we review advances made towards unravelling the genetic basis of sexual expression in palms. Our survey opens new perspectives for understanding how plant sexuality has evolved in angiosperms as a whole.