Morphological variation of the labellum of Vanilla pompona (Orchidaceae) in Oaxaca, Mexico

Abstract

In orchids, shape and size of floral traits such as the labellum serves to classify variation within and among species. The aim of this study was to characterize infra-specific morphological variation through the Vanilla pompona labellum, analyzing 80 flowers from 23 specimens from the state of Oaxaca, Mexico. The labellum of each flower was dissected and analyzed by geometric morphometrics, obtaining 60 variables that were grouped in the basal, middle and apical regions. An analysis of variance was performed considering the collections as sources of variation and 2 multivariate analyses, principal components and cluster analyses. Among collections, 58 variables were statistically significant. The model explained 81% of the total variation studied with the first 3 principal components. There is a floral morphological variation of the labellum in Vanilla pompona represented by 4 morphotypes in Oaxaca, likely result of the pressure and selection by pollinators and the environment, where the mountain system has possibly contributed as a geographic barrier