Floral characteristics support nocturnal pollination and pollination syndrome in Barringtonia racemosa

Abstract

To test for pollination syndrome and to complement records of foraging visitors of an associate mangrove, Barringtonia racemosa (L.) Spreng., aspects of its floral biology were investigated. Phenology and floral rewards (pollen viability, pollen histochemistry and nectar sugar concentration) were focused on owing to their role in plant-pollinator interaction. During the floral opening at 19:00, pollen viability, lipid presence and nectar sugar concentration were highest at 88.05 ± 0.98%, 80.69 ± 10.51%, and 68.98 ± 1.09% mg flower–1, respectively. Starch presence in pollen was rather low (mean 24.95 ± 14.58%), due to hydrolysis of starch occurring during anthesis. These floral characteristics, which reflected the highest reproductive activity, coincided with nocturnal foraging of previously recorded moth visitors. Although bats were rarely observed in previous studies, nocturnal anthesis complemented with the recorded large amount of sugar in nectar (68.98 ± 1.09% mg flower^–1 = 1158 J) might be sufficient to provide the average needs of nocturnally foraging bats. Investigation of floral characteristics to complement observation of floral visitors is highly recommended to give a better understanding of the pollination system. Moreover, this study supports the pollination syndrome concept, emphasizing the need for investigation of the role of floral rewards in plant-pollinator relationships.