• Premise of the study: Polyploidy, or whole genome duplication (WGD), is common in plants despite theory suggesting that polyploid establishment is challenging and polyploids should be evolutionarily transitory. There is renewed interest in understanding the mechanisms that could facilitate polyploid establishment and explain their pervasiveness in nature. In particular, premating isolation from their diploid progenitors is suggested to be a crucial factor. In order to evaluate how changes in assortative mating occur, we need to understand the phenotypic effects of WGD on reproductive traits.• Methods: We used literature surveys and a meta-analysis to assess how WGD affects floral morphology, flowering phenology, and reproductive output in plants. We focused specifically on comparisons of newly generated polyploids (neopolyploids) and their parents to mitigate potential confounding effects of adaptation and drift that may be present in ancient polyploids. • Key results: The results indicated that across a broad representation of angiosperms, floral morphology traits increased in size, reproductive output decreased, and flowering phenology was unaffected by WGD. Additionally, we found that increased trait variation after WGD was uncommon for the phenotypic traits examined. • Conclusions: Our results suggest that the phenotypic effects on traits important to premating isolation of neopolyploids are in general small. Changes in flowering phenology, reproductive output, and phenotypic variation resulting from WGD may be less critical in facilitating premating isolation and neopolyploiestablishment. However, floral traits for which size is an important component of function (e.g., pollen transfer) could be strongly influenced by WGD. In compliance with data protection regulations, please contact the publication office if you would like to have your personal information removed from the database.