EXTRAFLORAL NECTARIES THAT ATTRACT ANTS IN BROMELIACEAE - STRUCTURE AND NECTAR COMPOSITION

The occurrence of extrafloral nectaries in some species of Bromeliaceae (subfam. Pitcairnioideae) is reported for the first time in the following plants from central and northern Argentina: Deuterocohnia longipetala, Dyckia ferox, Dyckia floribunda, Dyckia aff. gilliesii, Dyckia ragonesei, and Dyckia velascana. Ants are attracted to the extrafloral nectar that is secreted in a very high concentration (around 80% weight to total weight) by nonstructural, nonvascularized nectaries located in the outer verticil of tepals. They do not possess a specially differentiated nectariferous tissue and the exudate is probably secreted through paracytic and anomocytic stomata. Sugars and amino acids were detected in the nectar, but alkaloids, reducing acids, proteins, phenols, and lipids were not. Amino acid concentration ranged from 121.3 to 975-mu-g/mL. In all the species there was a high concentration of sucrose (97.2 - 100%), whereas glucose and (or) fructose were absent or present in a small amount (0.4 - 1.5%).