Variation in morphology of Teucrium polium aggr. populations in Bulgaria

The aim of this study was to investigate natural serpentine and non-serpentine populations of Teucrium polium aggr. and to document the differences in their morphological traits, as well as estimate which characters are most likely contributing to differentiation of the populations. Nine populations distributed both on and off serpentine soils were investigated, and 12 different morphological features of 270 individuals were studied by univariate and multivariate statistical analyses. The results did not demonstrate clear delimitation of the serpentine from the non-serpentine populations. Using these ecotypes as classification factors in the discriminant analysis, it can be stated that stem height, leaf length in the fifth leaf pair, internode length between the fourth and the fifth leaf pairs, and corolla tube length are features with the greatest discriminant ability. The character variation was generally higher for the vegetative features, while reproductive features failed to demonstrate clear differences. The similarity groupings indicated by the cluster analysis were synchronous with groups distinguished by both the discriminant and PCA analyses. Significant differences were observed between sets of vegetative characters in all populations investigated.