Generalised pollination system of Erythrina dominguezii (Fabaceae:Papilionoideae) involving hummingbirds, passerines and bees

Abstract

Plants in the genus Erythrina are pollinated by birds, such that passerine pollination is the plesiomorphic state, whereas hummingbird pollination is the derived character. Phylogenetic studies suggest that Erythrina dominguezii belongs to a basal clade characterised as pollinated by both passerines and hummingbirds. Here, we characterise the pollination system of E. dominguezii. Floral morphology, nectar traits, breeding system, visitation rates and pollen deposition by its floral visitors were studied. Floral morphology of E. dominguezii showed traits associated with both passerine and hummingbird pollination. Nectar sugar concentration showed an intermediate value but closer to the hummingbird type; however, it was rich in hexose, which is typical of the passerine type. Approximately 5% of the flowers set fruits under free pollination. Almost 80% of recorded flowers were visited by birds, with the rest visited by hymenopterans (bumblebees and honeybees). Among avian pollinators, five species of hummingbirds and three passerine species were identified as pollinators. The hummingbird Chlorostilbon lucidus was the most efficient visitor in terms of pollen deposition and was second in frequency of visits. The passerine Icterus cayanensis was second in efficiency at depositing pollen and was the most frequent pollinator. Our results show that E. dominguezii has a generalised pollination system. In addition, we report a new case of closed flowers and secondary nectar presentation. This is the first study that compares effectiveness among different pollinators in Erythrina. © 2012 CSIRO.