The Predictive Value of Nectar Chemistry to the Recognition of Pollinator Types

ABSTRACT The analysis of “nectar sugar ratios” shows a close relationship between the sucrose/(glucose + fructose) ratio and the type of pollinator that visits the flowers. When taken in conjunction with the morphology of the flowers and inflorescence, these ratios can be good predictors of the pollinators. Predictions are made for Erythrina crista-galli (Fabaceae), where its hexose-dominated nectar suggests passerine-bird pollination in contrast to species which are hummingbird-pollinated. Similarly, the genus Puya (Bromeliaceae) contains species with abundant sucrose in the nectar (hummingbird-pollinated species) and species with abundant hexose belonging to the massive monocarpie subgenus Puya. In P. raimondii, the hexose-dominated nectar and the inflorescence morphology suggest that it will be passerine-bird pollinated in the high Andes where it is native. Luehea speciosa (Tiliaceae), in the American tropics, has hexose-rich nectar and we predicted that it would be bat-pollinated. No bats were seen to...