| Resumo: | We assessed nectar production patterns, the breeding system, and overall pollinator dependence of Psittacanthus schie- deanus (Schlecht. & Cham.) G.Don (Loranthaceae), a mistletoe species that blooms in the late summer of the eastern cloud forests of Mexico and whose owers are mainly visited by hummingbirds. Despite differences in nectar production rates over the lifespan of a ower, the daily nectar secretion of 3.6-7.2 mg sugar/ ower/day was high compared to other hummingbird-adapted plant spe- cies. Hand-pollination experiments showed that this plant is self-compatible, with only a slight advantage of cross- (xenogamous) and geitonogamous hand-pollinated owers over autonomous hand-pollinated owers. Hence, the high production of nectar by P. schiedeanus owers represents an important ecosystem resource that may mediate interactions with a wide variety of oral visitors. Although P. schiedeanus set selfed fruits autonomously, this plant requires hummingbirds to achieve its full reproductive potential.
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