Premise of research. Variation in floral traits is mainly attributed to variations in the abundance or taxonomic composition of the pollinator assemblage. The diversity and abundance of insect pollinators decrease with elevation, which might modify the allocation patterns of floral traits in plants (i.e., attraction or rewards) at high elevation to compete for pollinators. This competition would be pronounced between congeneric and sympatric species. In this study, we evaluated the pattern of flower size variation and the composition of floral visitor assemblages along elevation in two congeneric and sympatric species of Anthurium.Methodology. We investigated the variation of floral traits and the variation in the flower-visitor assemblages in Anthurium caucanum and Anthurium panduriforme in seven transects located every 100 m of elevation along an elevation gradient (2200–2800 m a.s.l.) for 1 yr. We measured floral size (spadix length and diameter and spathe length and width) and functional traits (number of flowers, ovules, and pollen grains; stigmatic area; and pollen-to-ovule ratio) in plants from each species.Pivotal results. Spadix length increased with elevation in A. panduriforme, while it decreased in A. caucanum. Pollen number (i.e., male function) and pollen-to-ovule ratio were higher in A. panduriforme compared with A. caucanum, while the opposite occurred with stigmatic area (i.e., female function). The abundance of flower visitors decreased at high elevation.Conclusions. The contrasting patterns of floral size variation, allocation patterns to the reproductive male and female functions, and pollen-to-ovule ratios suggest that the variation in the pollination context along elevation seems to have promoted differences in inflorescence morphology among these congeneric and co-occurring species, most likely to reduce competition for pollinators. This could drive the species to different reproductive and mating strategies, allowing them to be successful in the shared environment.