Floral and extrafloral nectar production in Anacardium occidentale L. (Anacardiaceae): an andromonoecious species.

Trees of Anacardium occidentale L. have secretory tissues in the hermaphrodite and male flowers, at the junctions of the panicle branches, on the adaxial leaf surface at the proximal end of the midrib, and on the young developing fruit at the site of abscission of the style. The structure of the floral and panicle nectaries was investigated in detail, as well as the nectar volumes and sugar and amino acid contents. Nectar was secreted by multicellular trichomes, apparently by diffusion through the cuticle. The panicle nectary secreted the largest volume, followed by the nectary of the hermaphrodite flower and then the nectary of the male flower, and the sugar concentration of all nectar types was high, at over 70%. All nectar types contained glucose, fructose, and sucrose, with glucose and fructose predominating in roughly equal amounts. The nectar of the male hermaphrodite flower contained the highest amount of sucrose, but the panicle nectar had the highest total sugar content. Fifteen amino acids were ...