Cacti species from the Brazilian Chaco: floral and fruit traits

Abstract

Cacti species are recognized for providing various resources for pollinators and seed dispersers in many ecosystems, being these interactions well documented in some of them. However, for the Brazilian Chaco, these interactions remain unknown. In this study we characterize flower and fruit traits, as well as the resources offered by six species of Cactaceae (Cleistocactus baumannii, Echinopsis rhodotricha, Harrisia balansae, Harrisia tortuosa, Opuntia retrorsa and Stetsonia coryne) in order to suggest their potential pollinators and seed dispersers. In an area of Chaco vegetation, located in the southwest of Mato Grosso do Sul, we collected flowers and fruits from November 2014 to January 2015 and performed morphometric analysis in the laboratory. The cacti species showed a great diversity of forms, with flowers presenting different periods of anthesis, colors, sizes and resources offered. According to predominant flower characteristics, such as white flowers opening at night, the potential pollinators of most species are probably nocturnal, such as moths and bats. All the recorded fruits are berries, with attractive colors (red or bright lilac), suggesting birds as potential seed dispersers. This study represents a starting point for better understanding interactions between cacti species and their mutualists in the Brazilian Chaco. However, detailed field studies are still required to confirm such interactions in this threatened ecosystem.