PHYLOGENETIC INFLUENCE ON TWINING CHIRALITY IN LIANAS FROM AMAZONIAN PERU

A majority of angiosperm species of vines and lianas use their stem apices for twining am l adherence to support structures. Prior observations have suggested a strong predominance of twining orientation in a dextral (right-handed) direction. We present here the chirality of twining (handedness) for 60 taxa representing 21 families encountered in a terra firme Amazonian forest community in Pent. We surveyed 145 stems of climbers that represented one to eight individuals of a given taxon. We demonstrate that dextral chirality is phylogenetically widespread among angiosperm stem climbers and suggest that phylogenetic deviations from the dextral pattern represent independent evolutionary events. Phylogenetic constraint might be invoked to explain the dextral dominance among climbers, but dextral circumnutation is not ubiquitous in other angiosperm organs. Here we also clearly define climbing chirality because of the confusion in previous literature, and we compile published family-level reports of deviations from dextral orientation. This study underscores the need for approaching the twining chirality of plants from genetic, developmental, and physiologic perspectives to clarify the basis for the preferred twining orientation among angiosperm climbers.