Leaves anatomical and physiological adaptations of Vinca major ‘Variegata’ and Hedera helix L. to specific roof garden conditions

Abstract

Urban agglomerations create extreme microclimates for plants, in which growth, development and survival means adaptation. Plantations expansions beyond the typical gardens to buildings, walls or other build structures were realized in many cities with a rigorous selection of plant species. Although the number of woody species well adapted to the urban environmental conditions is quite large, few species manage to grow and develop on the roofs. Two species - Vinca major ‘Variegata’ and Hedera helix, regularly used for this type of plantations in Bucharest, were selected to understand their mechanism of adaptation. A comparative study was conducted on these species, growing on a rooftop garden and at the ground level into a typical garden. Both species revealed considerable anatomical differences of the leaves. In addition, physiological determinations revealed a stronger intensity of photosynthesis, an intense transpiration and a lower respiration rate at plants grown in the roof garden.

The Morphological and Anatomical Traits of the Leaf in Representative Vinca Species Observed on Indoor- and Outdoor-Grown Plants

“…The Vinca leaves contain different numbers of columnar palisade cells. It was confirmed that sunlight-grown plants have more columnar palisade cells than those of shade-grown plants [ 29 , 34 , 35 ]. Similar to our results where the indoor plants had a less differentiated palisade tissue than the outdoor plants, other studies showed that the palisade tissue cells in V. major var.…”

“…There are quantitative and qualitative differences regarding the chemical composition of Vinca extracts, and previous studies showed that the morphological and anatomical traits of the leaves (shape and surface, cuticle, stomata, trichome, epidermis, etc.) are responsible for the chemical composition variability in the extracts [ 33 , 34 , 35 , 36 ]. These morphological and anatomical aspects of the Vinca leaf had been investigated in this study as well.…”

“…Additionally, the morphological characters of all plant organs are used for accurate identification of species [ 14 , 33 , 34 , 35 ]. The leaf shape varies within species and populations, and even within the same individual plants; therefore, it affects photosynthesis, water balance, temperature control, and the interactions with other organisms [ 39 ].…”

“…Stomata are important structures involved in exchange processes of the plant with the environment, balancing the CO 2 influx during photosynthesis and water vapor efflux during transpiration [ 28 , 33 , 35 , 40 , 55 ]. Stomata exhibit a diverse range of shapes, sizes, and numbers across different plant species [ 53 ].…”

“…Similar to our results where the indoor plants had a less differentiated palisade tissue than the outdoor plants, other studies showed that the palisade tissue cells in V. major var. variegata leaves were single-layered for the plants located at roof level and double-layered for ground-level plants [ 35 ]. Another study demonstrated that depending on light exposition, the leaf of V. minor had a double-layered palisade tissue and V. herbacea leaf, a single-layered one [ 41 ].…”