Reproductive biology of Piper species (Piperaceae): a review to link the past to the future

Abstract Piper species are important components of the understory in tropical and subtropical forests, and some species are of economic and medicinal importance. This genus has been studied in different areas of science. However, some questions remain unanswered after the new circumscription as proposed by phylogenetic studies. Here, I review different aspects related to the reproductive biology of Piper species (phenology, sexual expression, floral biology, pollination and mating systems), comparing the results between Neotropical (representing most of the studies carried out so far) and Paleotropical regions. Seventy-five species were analyzed. Some patterns can be observed, mainly in Neotropical species, such as the predominance of annual flowering and fruiting, dichogamy (generally incomplete protogyny) with gradual and sequential exposure of stigmas, asynchronous pollen release, and pollination by insects. Some aspects have been poorly studied, such as variations in sexual expression, the efficiency of different pollinators, and the chemical composition of floral volatiles associated with their role in pollination. In addition, I discuss remaining gaps and further studies that are required, mainly on Paleotropical Piper species, to obtain basic information on the reproductive biology of these plants. From this, comparisons with Neotropical species can be made, allowing the verification of patterns in this genus.