Daniela Ciccarelli

Coastline Dune Vegetation Dynamics: Evidence of No Stability

Coastal dune ecosystems are subjected to severe stress and disturbance factors that are particularly high in the beach-foredune environment and generally decrease with distance from the coast. The present study aimed to link plant species composition of coastal foredunes with the physical dynamical processes of the coastline in central Italy. A random hierarchical sampling design, based on two spatial scales (quadrant and parcel), was applied to estimate the variation in plant community composition. Permutational multivariate analysis of variance (PERMANOVA) revealed an approximately similar amount of variation with respect to both the coastal dynamic class and the parcel level. In addition, principal coordinate analyses showed that three taxa – Ammophila arenaria, Elymus farctus and Otanthus maritimus subsp. maritimus – were mainly linked to the coastal dynamics: A. arenaria increases its abundance where erosion of the shoreline is very high, while E. farctus and O. maritimus are more abundant in the prograding coast. Finally, similarity percentages analysis (SIMPER) highlighted that where the erosive processes were strongest, the number of the species contributing to the total similarity was the highest. This is likely to indicate instability and a strong disturbance of plant communities that results in an unstable equilibrium. These findings have important implications for management and conservation actions.

Glandular Hairs and Secretory Ducts of Matricaria chamomilla (Asteraceae): Morphology and Histochemistry

The aim of the present work is to characterize the glandular hairs and the secretory ducts of Matricaria chamomilla (Asteraceae) morphologically, anatomically and histochemically. The glandular hairs are multicellular and biseriate with two basal cells, two peduncle cells and a secretory head composed of six cells. The histochemical tests show that the glands are positive for lipids, essential oils, sesquiterpene lactones, and pectic—like substances. The secretory ducts show a lumen surrounded by a layer of specialized cells, with the exception in the root where the ducts do not show any secretory epithelium. The histochemical tests show that the ducts are always positive for lipids, while the tests for the presence of essential oils and sesquiterpene lactones are heterogeneous in the plant organs considered.

The “black nodules” of Hypericum perforatum L. subsp. perforatum : Morphological,anatomical, and histochemical studies during the course of ontogenesis

Hypericum perforatum L., traditionally used in folk medicine as a therapeutic plant, is today investigated for its antidepressant and antiretroviral activities. This species is characterized by the presence of different types of secretory structures: translucent glands or cavities, black nodules, and secretory canals. The aim of the present work is to characterize the black nodules on both the floral and vegetative parts, morphologically, anatomically, and histochemically. Nodules consist of a cluster of irregularly shaped cells surrounded by a single- or double-layered sheath. Histochemical tests show that the nodules are negative for the presence of lipids, essential oils, sesquiterpene lactones, steroids, and proteins and positive for pectic-like substances, tannins, and alkaloids. Our results show that the inflorescences are richest in nodules and are, there f ore, the best sites for the extraction of the secondary metabolites.

Morpho-functional adaptations in Cakile maritima Scop. subsp. maritima: comparation of two different morphological types.

Along the Italian maritime foredunes there are two different morphotypes of Cakile maritima Scop. subsp. maritima differing in leaf shape: one type is characterized by entire lamina, while the other one shows pinnatifi d leaves. Therefore, this study was performed to analyze leaf morpho-functional characters of both C. maritima morphotypes in order to highlight the peculiar adaptations to the ecological conditions of sand dune environments and to compare the two different morphological types. The morpho-functional traits analyzed are leaf roll, general morphology of epidermis, vesicular cells, salt crys- tals, stomatal apparatus, stomatal density (SD), hydathodes, mesophyll, idioblasts, specifi c leaf area (SLA) and leaf dry matter content (LDMC). The most interesting anatomical adaptations to sand dune habitats are thick epidermal cuticle; high stomatal density; epidermal vesicular cells involved in water storage, sunlight refl exion and together with hydathodes in salt elimination; high development of palisade and water storage parenchyma; bundle sheath typical of C 4 leaf anatomy. Differences in several leaf characters between the two morphotypes seem to suggest that pinnatifi d morphotype is more resistant to stress and environmental disturbance than the entire type. The analysis of C. maritima distribution in two different coastal traits affected by progradation or erosional processes confi rmed this hypothesis.

Functional groups in Lychnophorinae (Asteraceae: Vernonieae) based on morphological and anatomical traits

The Lychnophorinae subtribe (Asteraceae: Vernonieae) occurs mainly on the Central Brazilian Plateau, especially in areas characterised by intense solar radiation, large daily temperature fluctuations, water scarcity during autumn and winter, and frequent fire. However, a few species of Lychnophorinae, such as Blanchetia heterotricha DC., are not restricted to the Cerrado Domain, but can live in open and humid areas of borders of the Atlantic Forest. To understand the mechanisms of Lychnophorinae adaptation to these environmental conditions, habit, leaf and stem functional traits from 12 species were analysed. Leaf and stem samples were processed and stained using standard plant-anatomy methodology. A comparative analysis of functional groups was performed by principal coordinates analysis, which was applied to two matrices of 30 qualitative and five quantitative traits. The multivariate analysis based on qualitative traits highlighted the following four functional types that might be linked to ecological conditions: Group I adapted at open and humid areas of borders of the Atlantic Forest; Group II, with features mostly related to foggy habitats; Group III, exhibiting traits quite adapted to the seasonally dry and variable conditions of the campos rupestres; and Group IV, showing the most specialised morphological and anatomical traits, which might be related to the extreme conditions of the campos rupestres.

Secretory structures of Santolina ligustica Arrigoni (Asteraceae), an Italian endemic species

Santolina ligustica Arrigoni (Asteraceae) shows two different types of secretory structures: secretory ducts and glandular hairs. Ducts consist of a lumen varying in width surrounded by one or two layers of secretory cells. The size of the ducts varies in length and width, depending on the organ in which they are present. Hairs are multicellular and biseriate. They consist of two basal, two stalk, and six head cells. Ducts are located in the receptacle, interfloral and involucral bracts, in the stigma, in the leaves, stem, and root. They are absent in the corolla. Glandular hairs are present on the corolla, on the involucral and interfloral bracts, and in the stem and leaves. The histochemical analyses of the secretion of ducts and hairs show the presence of lipids, sesquiterpene lactones, alkaloids, and flavonoids. Although similar, the two secretions differ in the lipid composition: ducts produce both essential oils and resins, while hairs produce essential oils. Pectin-like substances and tannins seem to be produced by glandular hairs only.

Plant adaptation to extreme environments: the example of Cistus salviifolius of an active geothermal alteration field.

Cistus salviifolius is able to colonise one of the most extreme active geothermal alteration fields in terms of both soil acidity and hot temperatures. The analyses of morpho-functional and physiological characters, investigated in leaves of plants growing around fumaroles (G leaves) and in leaves developed by the same plants after transfer into growth chamber under controlled conditions (C leaves) evidenced the main adaptive traits developed by this pioneer plant in a stressful environment. These traits involved leaf shape and thickness, mesophyll compactness, stomatal and trichome densities, chloroplast size. Changes of functional and physiological traits concerned dry matter content, peroxide and lipid peroxidation, leaf area, relative water and pigment contents. A higher reducing power and antioxidant enzymatic activity were typical of G leaves. Though the high levels of stress parameters, G leaves showed stress-induced specific morphogenic and physiological responses putatively involved in their surviving in active geothermal habitats.

The role of sediment grain size, mineralogy, and beach morphology on plant communities of two Mediterranean coastal dune systems

Coastal dune ecosystems are characterized by a strong relationship between abiotic and biotic factors. The aim of the study is to identify the abiotic factors that mostly affect distribution and composition of plant dune communities along the coast-to-inland gradient, focusing the attention on sediment grain-size parameters, mineralogy, and dune morphology. The research was carried out on two coastal dune systems belonging to protected areas in the Mediterranean Basin, specifically in Northern and Southern Tuscany (Italy). Grain-size analysis, X-ray powder diffraction, topographic surveys, and floristic data recording were carried out along 11 transects perpendicular to the shoreline; the portion of the beach investigated is comprised within the foreshore and the backdune area. The analyses revealed some differences between the two coastal dune systems in terms of sediment parameters, mineralogy, and dune topography. The differences are mainly ascribed to the physical characteristics of the sites where the surveys were carried out. These data were matched with those provided by the vegetation sampling and then statistically processed by means of methods such as the Canonical Correlation Analysis (CCA), which showed that the mean grain-size is the most important abiotic factor that influences the composition of these coastal plant communities. These results might be considered to improve and optimize management and conservation programs for these ecosystems, since nowadays artificial dune reconstruction is a practice frequently used as a form of coastal protection.

Chemical Composition of Essential Oils and Aromatic Waters from Different Italian Anthemis maritima Populations

The chemical composition of the essential oils and aromatic waters isolated from six Italian Anthemis maritima populations was determined by GC‐FID and GC/MS analyses. In total, 122 and 100 chemical compounds were identified in the essential oils and the aromatic waters, respectively. The main compound classes represented in the oils were monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpene hydrocarbons, oxygenated sesquiterpenes, and terpene esters. Multivariate chemometric techniques such as cluster analysis (CA) and principal coordinate analysis (PCO) were used to classify the samples according to the geographical origin. Statistical analysis allowed the attribution of the analyzed populations to different chemotype groups.

Ontogeny of secretory cavities in vegetative parts of Myrtus communis L. (Myrtaceae): an example of schizolysigenous development

Myrtus communis L. is an evergreen shrub, typical of the Mediterranean scrub. This species is characterized by the presence of secretory cavities, the vegetative parts of which have been investigated morphologically and anatomically. The ontogenesis of secretory cavities is schizolysigenous: a combination of schizogenous and lysigenous development. At maturity, glands are made up of a sheath of flattened cells, and secretory cells are completely degenerated.