The selection of floral and reproductive traits is influenced by the plant’s abiotic environment, florivores and pollinators. Leroy et al. show that mutualistic associations with ants can result in an enhanced reproductive allocation for the tank‐bromeliad Aechmea mertensii. They find that association with Camponotus femoratus results in more and larger inflorescences, more flowers and fruits, and more and larger seeds than for plants associated with Pachycondyla goeldii. Thus the different activities and ecological preferences of these two ant species may play a contrasting role in shaping the evolution and speciation of this bromeliad.