EXTRAFLORAL NECTARIES AS ADAPTATIONS FOR BIRD POLLINATION IN ACACIA TERMINALIS

Abstract

Characteristics of the flowering trees of Acacia terminalis may be interpreted as adaptations for bird pollination. Each leaf bears a single red nectary up to 12 mm long on its petiole. Nectaries show greatest secretory activity at flowering (max. 15 μ l/nectary/day), and nectar was found only in the early morning. The nectar contains a mean of 16% sugars (max. >50%) and is hexose rich with 18 amino acids, especially glutamine and phenylalanine. Analyses of foraging dynamics and pollen loads from feathers of passerine birds further support this interpretation.