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