Morpho-anatomical adaptation of the leaves of certain Veronica species to arid conditions

Abstract

This study’s objective was to evaluate the adaptive potential of the leaves of Veronica (V. austriaca, V. incana, and V. prostrata) in the arid conditions of the Kryvyi Rih Botanical Garden NAS of Ukraine (KBG) located in the Right-Bank Steppe Cisdnieper. Leaves have been obtained from the collection of ornamental plants of KBG, where these plants are introduced for ten years. The seasonal dynamics of leaf development have been studied during the growing season of 2018, when the most arid climatic conditions were observed. The leaves of the investigated species were found to be dorsoventral, amphistomatic, with an anomocytic stomatal apparatus and bifacial mesophyll. Changes in the anatomical structures of the leaf blade towards xeromorphism were determined. In particular, in all studied specimens thickening of the cuticle, adaxial and abaxial epidermises (except V. prostrata, where the upper epidermis decreased by 35 %) mesophyll occurred. The number of stomata on the abaxial epidermis in all species decreased (the most notably in V. prostrata). Such increase of xeromorphism in V. austriaca, V. incana, and V. prostrata is an adaptive reaction of plants to the effects of extreme arid weather and climatic conditions of the Kryvorizhzhya, which testifies to the plasticity of investigated species and their high adaptation potential to the climatic conditions of the Right-Bank Steppe Cisdnieper.

Keywords

• Veronica
• anatomy
• leaf
• plasticity
• drought resistance