Nontrivial Variations of Morpho-Anatomical Leaf Traits in Natural South-Eastern Populations of Vaccinium species from Central Balkans

Abstract

Morpho-anatomical characteristics of Vaccinium myrtillus, V. uliginosum and V. vitis-idaea leaves from several sites of the Central Balkans were examined. The aim of this study was to investigate for the first time morpho-anatomical leaf traits of these species in the studied populations and to identify traits that follow a specific trend along the gradients of climate factors. Leaf traits that discriminate Vaccinium species were as follows: depth of the adaxial cuticule (AdC), thickness of the palisade tissue (PT), thickness of the spongy tissue (ST), height of the abaxial epidermal cells (AbE), height of the abaxial cuticule (AbC) and leaf thickness (LT). Populations of V. myrtillus were characterized by the smallest, and populations of V. vitis-idaea by the highest values for AdC, PT, ST, AbE and LT. Additionally, AbC was significantly larger for V. uliginosum in comparison to two other species. On the basis of morpho-anatomical traits, intraspecific variability of the studied species was explored by Principal Component Analysis (PCA), Cluster Analysis (CA) and Analysis of Variance (ANOVA). CA based on 10 morpho-anatomical traits showed that populations of V. myrtillus and V. uliginosum that grew at lower altitudes (characterized by higher mean annual temperature) are more similar to each other. Especially V. myrtillus was responsive to the elevational gradient and exhibited the highest plasticity in morpho-anatomical leaf traits. Populations of V. vitis-idaea had a different pattern of differentiation along the elevational gradient. CA showed that the populations at the lowest and at the highest altitudes were more similar according to the morpho-anatomical leaf traits, meaning that evergreen leaves were more resistant to environmental conditions.