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Chaenomeles japonica is an attractive ornamental shrub flowering in spring. It is also a valuable source of nectar and pollen for entomofauna. The study was carried out to investigate the structure of hypanthial nectaries present in the flowers of this species with the use of light and scanning electron microscopy. Nectary tissues were examined in three stages of flowering, with special focus placed on changes occurring in the epidermis and nectariferous parnechyma. Long-styled flowers, which produce nectar abundantly, were selected for the study. The nectary parenchyma was shown to consist of multiple cell layers (up to 20). The epidermis was initially single-layered, but the number of layers gradually increased to 2–3 during the following days of flowering. The outer walls of epidermis cells were covered by a strongly undulating cuticle with massive striae. Cracks and perforations, which are probably nectar release sites, were visible between the striae. The presence of the secretion in the intercellular spaces between the parenchyma layer and the epidermis may indicate apoplastic nectar transport. The presence of stomata, as well as pores in the cuticle layer of the nectary epidermis, suggests that C. japonica nectar is secreted in two ways: (i) through the nectarostomata and (ii) ordinary epidermis cells with the involvement of the cuticle. [ABSTRACT FROM AUTHOR]

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 terms of flowering ecology, Pulsatilla flowers are classified as "pollen flowers" producing inconsiderable amounts of nectar. The aim of this study was to assess the length of the flowering period in Pulsatilla slavica and P. vulgaris and to investigate the structure of the epidermis of the perianth and generative elements of their flowers. Special focus was placed on the structure of hairs and the distribution of stomata. The weight of nectar released by the flowers of the two Pulsatilla species and the content of sugars in the nectar was also evaluated. In SE Poland, both species flowered for similar periods between the second half of April and the first half of May. The flower life-span of both was determined to be 9-14 days. The lower part of each sepal was observed to be covered by long hairs having cellulose-pectin cell walls of varying thickness. Hairs present on the pistil style are thinner; they may provide some protection against cold and can play a role of a secondary pollen presenter for insects. The bowl-shaped structure of the perianth and the nature of the adaxial surface of the sepal epidermis may facilitate reflection of sunlight into the inner parts of the flower, which may contribute to an elevation of the intraflower temperature. This is particularly important for the functionality of the ovary. The surface of the hairs was seen to be covered by a cuticle ensuring water impermeability. Flowers are visited by honeybees, bumblebees, butterflies, and ants, for which nectar and pollen are the main attractants. Ants, which are regarded as illegitimate flower visitors, were found to cause damage to the androecium. The number of fruits produced in the flowers of both Pulsatilla species was lower than 50% of the number of pistils. [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]

Many plants develop in the petal epidermis papillae emitting essential oils. In species of the genus Allium, papillae occur in the ovary epidermis. The aim of this study was to determine the structure of papillae in Allium karataviense Regel and to perform histochemical tests that would allow the components of their secretion to be investigated, mainly the presence of essential oils. Examination was performed using light and scanning electron microscopy. It was found that in conical papillae, with a height of about 83 μm, there were large cell nuclei, a thick outer wall with a layer of striated cuticle, and a varying degree of cell vacuolation, depending on the age of the ovary. Using histochemical reactions, we demonstrated neutral lipids, acid lipids and pectins to occur in the papillae. Neutral lipids are characteristic of essential oils. [ABSTRACT FROM AUTHOR]

The intensely fragrant flowers of the Rosa rugosa Thunb. have been applied in medicine, and food and cosmetic industries. The species is cultivated for production of rose essential oil (Oleum Rosae) from its flowers. R. rugosa petals secrete the largest quantities of essential oil. The aim of the study was to identify the characteristics of the epidermis of both sides of the petal and to observe whether adaxial and abaxial epidermal cells can secrete essential oil. The investigations were conducted using light and scanning electron microscopy. The analyses were focused on petal thickness and characteristics of the mesophyll. The study has demonstrated that only adaxial epidermal cells form conical papillae covered by massive cuticular striae. The surface of the papillae displayed remnants of a secretory substance. In turn, the inner walls of the abaxial epidermal cells were flat and covered by a striated cuticle, which exhibited various striation patterns. Fragrant substances stored under the cuticle caused local stretching thereof and disappearance of striation. The results of our observations allow a statement that the cells of the adaxial and abaxial epidermis of R. rugosa petals differ in terms of the structure and they secrete fragrant substances. [ABSTRACT FROM AUTHOR]

The present study is a continuation of our research on the structure of healthy leaves of Aesculus hippocastanum and leaves damaged by larvae of Cameraria ohridella. In this study, the epidermal micromorphology of both leaf surfaces in A. hippocastanum was investigated by scanning electron microscopy (SEM). Light microscopy was used to examine on which side of the leaf blades eggs of Cameraria ohridella were laid. The characteristic features of the adaxial and abaxial epidermis were shown. In the hypostomatic leaves of the studied species, the stomata occurred at a density of 173 x mm-2 and they represented the cyclocytic type. A striated layer of the cuticle was observed only in the adaxial epidermis in which glandular hairs were also present along the midribs. Non-glandular trichomes grew only on the surface of the midribs or in their axils in the abaxial epidermis. We found eggs of C. ohridella only on the adaxial surface of the epidermis. Using SEM, we also observed in the mines leaf tissues damaged by C. ohridella. We found palisade parenchyma to be absent, whereas in the spongy parenchyma there could be seen large intercellular spaces and at places a dense mass of organic matter, formed from damaged cells and larval excrement. The vascular bundles and calcium oxalate crystals remained in the feeding places. We found numerous bacteria, fungal spores and hyphae as well as cleistothecia of Erysiphales in the mines on the surface of the damaged mesophyll. The glandular trichomes occurring only locally on the leaves, the relatively thin cell walls of the epidermis and a not well-developed cuticle layer on their surface do not protect sufficiently these leaves against the invasion of C. ohridella. On the other hand, damaged tissue areas are a convenient place for the growth of bacteria and fungi. [ABSTRACT FROM AUTHOR]