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Heracleum sosnowskyi Manden. was introduced in Poland as a fodder plant. Currently, it is regarded as an invasive plant posing a health hazard to humans and animals and a threat to native flora. The aim of the study was to localise furanocoumarins in the stem and leaf tissues. The investigations were carried out using light, fluorescence, and scanning electron microscopy as well as histochemical assays. The epidermis of the analysed organs bears live, non-capitate hairs with variable length, which contain lipids, essential oils, polysaccharides, tannins, and furanocoumarins. The observations performed with scanning electron microscopy revealed the presence of a foamy substance and furanocoumarin crystals on the surface of the trichomes and other epidermal cells, as well as in the parenchyma cells. Characteristic furanocoumarin autofluorescence was present in the epidermis and on its surface, as well as in the subepidermal parenchyma. Secondary fluorescence was emitted by furanocoumarins in different leaf petiole tissues: psoralen, bergapten, and xanthotoxin. We have detected for the first time the presence of furanocoumarins in different tissues of leaves in H. sosnowskyi. Furanocoumarins were also abundantly present on the epidermal surface of cells. This explains why the contact with the plant is dangerous to humans and results in development of photodermatoses. [ABSTRACT FROM AUTHOR]

In Poland Scorzonera hispanica L. is rare in the wild. This species is used as a vegetable and medicinal plant. Currently, attempts are being made to introduce this plant into cultivation in Poland. In this study, comparative analyses were conducted of the epidermis surface micromorphology and anatomical structure of the leaves of S. hispanica 'Maxima' and 'Meres'. The investigations were performed using fluorescence, light and scanning electron microscopy. The cuticle on the surface of epidermal cells is smooth or striated. In the epidermis, there are anomocytic stomata. The stomatal index in the epidermis of the studied cultivars is 9.3-11%. In the midrib of the leaf, there is an aerial cavity which occupies a substantial area. In this place, cracking and breaking of the leaf blade were observed. Over the aerial cavity under the adaxial epidermis, there is a single layer of collenchyma cells and 1-2 rows of parenchyma cells. Tangential collenchyma is also present between the abaxial epidermis and large vascular bundles located in the midrib and on both sides of the large vascular bundles in the lamina. This tissue strengthens the leaf margin. The mesophyll cells located in the abaxial epidermis of the midrib form protrusions surrounding the large vascular bundles. The leaves of S. hispanica represent the equifacial type. [ABSTRACT FROM AUTHOR]

In its stems and leaves, Heracleum sosnovskii Manden. contains furanocoumarins, which exert a phototoxic effect on humans. The aim of the investigations was to describe the external secretory structures of the epidermis and internal secretory tissues in organs responsible for emission of secretion that is toxic to human skin. The study was conducted using light and fluorescence microscopy. On the stems and leaves, various types of secretory trichomes with dispersed or deposited secretion were found. The trichomes were most abundant on the abaxial leaf surface. Epidermal cells and the secretion present on the trichomes exhibited intense fluorescence, which may indicate the presence of furanocoumarins in the tissue and trichome secretions. [ABSTRACT FROM AUTHOR]

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Calcium is one of the most poorly reutilized nutrients. Its deficiencies cause various physiological disturbances and, consequently, reduce the quantity and quality of yields. Reduced content of Ca2+ ions in cells leads to development of, e.g., bitter pit in apples. Efficient and instantaneous mitigation of Ca2+ deficiencies is provided by foliar feeding. There are no detailed data on the effect of foliar feeding with various calcium forms on the cell structure or on the microanalysis and mapping of this element in apple fruit cells. Therefore, we carried out comparative studies of the ultrastructure of epidermis and hypodermis cells, to assess the content and distribution of calcium in the cell wall, cytoplasmic membrane, cytoplasm, and precipitates of Malus domestica Borkh. 'Szampion' fruit exposed to four Ca treatments, including the control with no additional Ca supplementation (I) and foliar applications of Ca(NO3)2 (II), CaCl2 (III), and Ca chelated with EDTA (IV). Light and transmission electron microscopy and an X-ray microanalyzer were used and showed a beneficial effect of calcium preparations on the ultrastructure of fruit epidermis and hypodermis cells, manifested in the presence of a normally developed cell wall with a regular middle lamella, preserved continuity of cytoplasmic membranes, and stabilized cell structure. In the selected elements of apical epidermis cells, the highest level of Ca2+ ions was detected in the middle lamella, cell wall, plasmalemma, and cytoplasm. The highest increase in the Ca2+ content in these cell constituents was recorded in treatment IV, whereas the lowest value of the parameters was noted in variant III. [ABSTRACT FROM AUTHOR]