ABSTRACT
Two sites in the Amazon basin are compared with respect to the composition of the stem-twining climbing plants (lianas and vines) and their orientation (chirality) during ascent. Censused were those species whose main mechanism for ascent is apical circumnutation of the stem. Although dextral and sinistral orientation might be assumed to be distributed evenly among individuals, species, genera, and families, earlier work has demonstrated an overwhelming preponderance of dextral chirality. Following up on earlier work from the western Amazon basin in Peru (Los Amigos Biological Station), we sampled a new site in eastern Mato Grosso state of Brazil (Rio Ronuro Ecological Station) and compared the proportion of climbers showing dextral, sinistral, and both chirality orientations. We found that proportions of dextral chirality in Brazil are indistinguishable from those in Peru, and even from other sites worldwide. We point out certain species pairs or individual species that may be of interest in untangling the cause of this asymmetric distribution in twining orientation.
