Pollination ecology of Geoffroea decorticans (Fabaceae) in central Argentine dry forest

We examined whether fruit production in the South American endemic tree Geoffroea decorticans depends on pollinators. Although diverse native pollinators were recorded, Apis mellifera reached >60% of the visits. Honey bees can pollinate efficiently but promote mainly geitonogamous pollination. Geoffroea decorticans is facultatively xenogamous and can produce few fruits from selfing. The best fruit set was produced by hand-xenogamous pollination. Fruit set by hand self- and natural-pollination were similarly less. Although floral display was relatively constant throughout the reproductive season, a decrease was observed in both pollinator activity and fruit production. We conclude that successful fruit production in G. decorticans depends on pollinator activity, but is actually limited by the quality of the pollen transferred by A. mellifera. (C) 2002 Elsevier Science Ltd.