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The increasing commercial production of R. idaeus offers insects nectar and pollen rewards, thus increasing the chance of cross-pollination, which enhances fruit yields. The knowledge of nectar characteristics may help farmers/beekeepers to improve the quality of their products. Therefore, we determined and compared nectar weight, sugar concentration and weight, and the qualitative and quantitative composition of sugars and amino acids in the nectar of six raspberry cultivars: three biennial and three repeated fruiting cultivars. The nectary abundance in these cultivars ranged between 20.2 ± 3.84 mg ('Polka') and 26.4 ± 7.3 mg ('Glen Ample') of nectar per flower with a sugar concentration of 34.6 ± 5.61–47.3 ± 9.33%. The contents of glucose and fructose (g/100 g) were in the range from 42.96 ± 0.71 ('Glen Ample') to 46.94 ± 0.55 ('Laszka') and from 50.7 ± 1.43 ('Polka') to 54.2 ± 0.72 ('Radziejowa'). Sucrose was detected only in 'Glen Ample' (5.6 ± 1.12 g/100 g) and 'Polka' (6.2 ± 0.95 g/100 g). Taking into account the increasing sugar weight in the nectar, the cultivars were ranked as follows: 'Polka' < 'Polana' < 'Radziejowa' < 'Pokusa' < 'Laszka' < 'Glen Ample'. The nectar of the analyzed raspberry cultivars was classified as a hexose-dominant type. Aspartic acid, glutamic acid, and proline were the most dominant endogenous amino acids, whereas exogenous acids were dominated by lysine and leucine. The present results provide valuable information about the nutritious value of R. idaeus nectar for pollinators. [ABSTRACT FROM AUTHOR]

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]

There is very scanty information concerning the floral nectary structure and nectar secretion in Prunus laurocerasus L. Therefore, the aim of the study was to determine the micromorphology, anatomy and ultrastructure of nectaries; the abundance of nectar production; and the quantitative and qualitative composition of sugars contained in the nectar of two P. laurocerasus cultivars: 'Schipkaensis' and 'Zabeliana'. The nectary structure was studied using light, fluorescence, scanning and transmission electron microscopy techniques. The nectar sugars were analysed with HPLC. The 'Schipkaensis' had longer inflorescences with a larger number of flowers and a longer perianth than 'Zabeliana'. The micromorphological structure of the nectaries in 'Schipkaensis' exhibited denser (approx. 39%) and larger (approx. 50%) stomata and thicker (approx. 13%) cuticular striae forming wider bands (approx. 26%) than in 'Zabeliana'. The results provide new data on the micromorphology, anatomy and ultrastructure of these floral nectaries. Nectary cuticle ornamentation as well as the size, type and density of stomata and stomatal complex topography can have a diagnostic value in Prunus. The nectar sugar weight indicates a significant apicultural value of the cherry laurel, especially in the case of 'Schipkaensis'. Cherry laurel is an entomophilous species recommended for cultivation in nectariferous zones and insect pollinator refuges; however, climatic conditions eliminating the invasiveness of these plants should be considered. [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]

Aesculus hippocastanum L. is an ornamental tree appreciated for its beautiful flowers and leaves. The flowers of this species contain secondary metabolites exhibiting pharmacological activity. They also produce essential oils and coloured "nectar guides", which enable insects to reach nectar and pollen. The aim of the study was to investigate the types and characteristics of chestnut flower trichomes, which may contain biologically active substances. The analyses were performed using light, fluorescence, and scanning electron microscopy. Three types of trichomes were found on the sepals and the surface of the ovary, whereas the corolla petals exhibited two types of hairs and papillae. The hairs differ in terms of their length and number of cells. The perianth and pistil had no capitate hairs, whereas the ovary exhibited the presence of colleters. Histochemical assays revealed that all the types of trichomes and papillae contained lipids or essential oils; hence, they can be classified as glandular structures. The "nectar guides" were characterised by higher density of secretory hairs than that on the rest of the petal surface, which implies that these petal fragments may emit stronger fragrance. [ABSTRACT FROM AUTHOR]

The article focuses on a research conducted to examine the nectar production and location and structure of the floral nectaries in the melliferous plant Daphne mezereum (D. mezereum) flowers. Topics discussed include high content of daphnin and coumarins in the D. mezereum's bark and Daphne odora's leaf buds, secretion of nectar onto the nectary surface of the stomata, and role of corolla filled with nectar in attracting bees and butterflies to the flower.