Floral biology of Echinopsis chiloensis ssp. chiloensis (Cactaceae): Evidence for a mixed pollination syndrome

Abstract: In this study the flower biology of Echinopsis chiloensis ssp. chiloensis, a columnar cactus occurring in Central Chile, is investigated, in particular its pollination syndrome, its visitors, their frequencies and behaviors and their pollination efficiencies. As statements on floral anthesis of this species are contradictory, this study also intended to elucidate both its beginning and duration. A pollinator exclusion study of a total of 162 flowers from 12 plants was conducted at one of the two study sites. Fruit and seed production as well as seed viability were documented to evaluate pollinator efficiencies. Anthesis proved to be nocturnal and diurnal, its duration and beginning was inversely proportional to maximum day temperatures. The experiment revealed that nocturnal and diurnal pollinator guilds both contributed to fruit set and that nocturnal pollination was more efficient. Yet, the efficiency of each of the members of the three pollinator guilds was limited for different reasons such as scarcity, unpredictability or specific pollination behaviors. Although E. chiloensis has nocturnal flowers, various floral traits where found to differ from the classical hawkmoth pollination syndrome, suggesting a shift from the specialized nocturnal to a more open pollination syndrome, thus adding to fruit set when hawkmoths are locally or temporarily scarce. [ABSTRACT FROM AUTHOR]