Nectar sugar composition in Southern African Papilionoideae (Fabaceae)

The nectar sugar composition of several genera of the subfamily Papilionoideae (Fabaceae) have been analysed, including many southern African endemic genera of the tribes Crotalarieae, Podalyrieae and Liparieae. Nectar sugars were found to be conservative characters with limited taxonomic value. Most of the samples contained high concentrations of sucrose, reaching nearly 100% in species of Virgilia and Cyclopia of the tribe Podalyrieae. Fructose and glucose are present in more or less equal amounts, and are the dominant sugars in the nectar of Erythrina and Sutherlandia (both bird-pollinated) but also in Pearsonia and some species of Lotononis both bee-pollinated). The conservative nature of nectar sugars is clearly seen in the two species of Liparia (tribe Liparia) where there are morphological adaptations to bird pollination in L. splendens but no corresponding difference in the sugar composition of the nectar.