Flooding and floral variation in a clonal aquatic plant

Environmental conditions govern the balance between sexual and clonal reproduction. In clonal heterostylous species, deviations from equal morph ratios commonly occur in association with stochastic forces and limited sexual recruitment. Cunha et al. report variation in morph frequencies and floral traits in the tristylous clonal aquatic Eichhornia azurea in the Pantanal wetlands of Brazil. They demonstrate that although most populations are tristylous, biased morph ratios predominate and in some areas there is differentiation in floral traits, including smaller flowers and pollen. They find an unexpected lack of differences in morph evenness among flooding regimes, and propose that floral differentiation is associated with the breakdown of tristylous characters owing to the absence of specialized pollinators.