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The distinctive features of floral nectaries facilitate identification of ecological and phylogenetic links between related taxa. The structure and functioning of nectaries determine the relationships between plants, pollinators, and the environment. The aim of the study was to determine and compare the micromorphology of the epidermis in the floral nectaries of six Rubus idaeus cultivars belonging to biennial ('Glen Ample', 'Laszka', 'Radziejowa') and repeated fruiting ('Pokusa', 'Polana', 'Polka') groups. Another objective was to characterize the cuticle ornamentation and stomatal morphology, the anatomy of the nectary epidermis, parenchyma, and sub-nectary parenchyma in the initial nectar secretion phase, as well as the ultrastructure of the nectary epidermis and parenchyma cells in the initial and full nectar secretion phases. The study was carried out using light, fluorescence, scanning and transmission-electron microscopy techniques. Semi-thin and ultrathin sections were used for the microscopic analyses. The cuticular ornamentation and stomatal morphology may be helpful elements in the identification of relatedness between Rubus species. The interaction of the extensive system of endoplasmic reticulum membranes, mitochondria, and Golgi apparatus indicates high metabolic activity, and the fusion of transport vesicles with the membrane suggests granulocrine nectar secretion. The results bring new data to the biology of plants. [ABSTRACT FROM AUTHOR]

Representatives of the family Sapindaceae exhibit high morphological diversity of the nectary structure. The present paper shows for the first time the results of micromorphological, anatomical, and ultrastructural analyses of floral nectaries in Aesculus hippocastanum. We have also described the forage and signal attractants of these flowers, which are important for the ecology of pollination. Using light, fluorescence, and electron microscopy, we demonstrated that the A. hippocastanum nectary forming a lobed disc is histologically differentiated into the epidermis with stomata, nectariferous parenchyma, subglandular parenchyma, and vascular bundles reaching the basal part of the nectariferous parenchyma. The use of histochemical assays revealed the presence of insoluble polysaccharides, lipids, terpenoids, and polyphenols including coumarins in the nectary tissues. Nectar is exuded onto the nectary surface via stomata and the permeable cuticle. As indicated by the observation of the ultrastructure of the nectary cells, transport of pre-nectar into parenchymal cells may proceed via the symplast and apoplast. We have also demonstrated that nectar transfer outside the protoplasts of parenchymal cells has a character of granulocrine secretion. A. hippocastanum flowers produce nectar abundantly; one flower secreted on average 2.64 mg of nectar and the concentration of sugars in the nectar was 33%. [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]