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Tilia cordata is a good source of food attractants for bees. These insects are the primary pollinators of flowers of this species. Nectar is produced in the floral trichoma-tous nectaries located on a projection of the adaxial, basal part of the sepals. There were two types of non-glandular hairs on the sepals; the first one to prevent the nectar f...
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The structure of floral nectaries of ivy (Hedera helix) was investigated under light, scanning, and transmission electron microscopes. The nectar of ivy is located on top of the inferior ovary forming a distinct undulating disc between the base of petals and the style. The ivy nectary represents open and persistent nectaries. During consecutive day...
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... Similar to other trees growing in urban conditions, limes create natural barriers against wind, reduce noise, and trap pollution. The dense lime crowns absorb a substantial part of solar radiation (even over 90%), thereby significantly lowering the air and soil temperature on hot days [3,4]. Moreover, lime trees emit negatively charged ions, which have a positive effect on human health [5]. ...
With their numerous natural and functional values, lime trees are recommended for planting in urban greenery. However, the allergenic properties of lime pollen should be taken into account. The aim of the study was to analyze the concentration of airborne lime pollen and the course of pollen seasons in this taxon in 10 cities in Poland in 2020. The aerobiological analyses were carried out in Bialystok, Bydgoszcz, Cracow, Lublin, Olsztyn, Opole, Piotrkow Trybunalski, Sosnowiec, Szczecin, and Warsaw. The investigations were conducted with the volumetric method using Burkard or Lanzoni pollen samplers. The 98% method was employed to determine the length of the pollen season. The earliest onset of the lime pollen season was recorded in Opole and Warsaw (14.06), and the latest date was noted in Sosnowiec (23.06). The maximum lime pollen concentrations were reported between 1.07 and 6.07 in most cities and on 24.06 only in Lublin and Opole. The highest annual pollen sums were recorded in Lublin (738), similar to those reported in 2018 and 2019, whereas the lowest values were noted in Bialystok (20), Sosnowiec (145), and Olsztyn (149). The annual sums of lime pollen in the other measurement sites located in the different regions of Poland were in the range of 180-308. In the discussion, the results from 2020 for Lublin are compared with data from the previous 19 years collected in this city. The data suggest that the increase in the airborne lime pollen concentration recorded in Lublin in recent years may be associated with climate change.
... In Tilia, five-petaled flowers in clusters most often numbering 3-7 are borne in cymose inflorescences. They produce yellowish-white petals and bright green sepals, on which trichomatous nectary glands are located (Szweykowska and Szweykowski, 2003;Konarska, 2013). In the androecium with numerous stamens, whorls of 5 stamens are distinguished (Maurizio and Grafl, 1969). ...
Lindens belong to valued trees that are frequently planted in urban green areas. Nevertheless, during their flowering they can pose a risk to sensitive people in cities due to their allergenic pollen. This paper presents the results of a 3-year phenological study (2016–2018) and an 18-year aerobiological study (2001–2018) conducted in Lublin (Poland). The flowering phenology data for the following five species: T. americana, T. cordata, T. × euchlora, T. platyphyllos, and T. tomentosa, were compared with the data regarding Tilia pollen seasons. It was shown that the largest amounts of airborne Tilia pollen grains occur during the full flowering period of T. cordata and that the flowering sequence of the linden species studied is constant during the growing season: T. platyphyllos, T. americana, T. cordata, T. × euchlora, and T. tomentosa. We found pollen seasons to start earlier by 14 days and to be extended by 15 days. Throughout the study period, the annual Tilia pollen sum did not change significantly. However, in 2018 in which there was a significant increase in temperature above the average for the previous 17 years, flowering and pollen release distinctly accelerated, and the annual pollen sum increased more than three times compared to the average for the previous 17 years.
In central-eastern Poland, the risk of pollen allergy due to the presence of Tilia pollen occurs in May, June, and July. We recorded the highest linden pollen concentrations in June. Due to the acceleration of flowering and pollen release in linden trees as a result of global warming, the incidence of pollen allergy in central Europe can be expected to become more intense already in the second half of May. Therefore, linden plantings in new urban green areas should be planned to be established at some distance from residential estates.
... Linden flowers are pentamerous and have numerous stamens and one pistil. Nectar is produced in trichomatous floral nectaries located at the protrusion of the basal part of the sepals (Anderson, 1976;Konarska, 2013;Yousefzadeh et al., 2013). Lindens grown in Poland are characterised by varied abundance of flowering. ...
All lindens provide Apidae insects with nectar, pollen, and honeydew. Lindens are important melliferous trees in Poland. The first purpose of the study was to carry out phenological observations of the flowering in ten linden taxa. The second aim was to analyse the content of linden pollen grains in the air of Lublin. A correlation between the parameters of the pollen season and meteorological factors was also determined. This study was conducted in the city of Lublin located in the central-eastern part of Poland. The flowering phenophases were analysed, using the method developed by Łukasiewicz, during the growing seasons of 2012-2015. Aerobiological monitoring, which was based on the volumetric method, was carried out over the 2001-2014 time period. As shown in the study, the flowering period of all the analysed linden taxa lasted 7 weeks, on average, from June 7 to July 24. The average length of the flowering period of the investigated taxa and hybrids was in the range of 12-17 days. Their flowering periods overlapped. The atmospheric pollen season lasted, on average, from mid-June to the second 10-day period of July. The highest concentration of airborne pollen was noted at the end of June. The pollen season pattern was significantly affected by temperature and relative air humidity as well as by rainfall in May and June. The investigations indicate a 9-day acceleration of the pollen season, which may be associated with global warming.
... The cells of secretory parenchyma, mainly in E. fortunei, contained phenolic compounds. Their presence in the nectaries of other Celastraceae representatives has also been reported by Matthews and Endress (2005) and Gomes and Lombardi (2013), and phenolic compounds in the nectaries of other plant species have been described by other researchers (Beardsell et al. 1989;Espolador Leitão et al. 2005;De-Paula et al. 2011;Konarska 2013;Montenegro et al. 2013;Nepi 2014). Moreover, all the aforementioned Euonymus species organs and, particularly, fruits contain toxic glycosides and alkaloids applied in medicine (Thomas et al. 2011;Sharma et al. 2012;Zuo et al. 2012). ...
The inconspicuous Euonymus L. flowers are equipped with open receptacular floral nectaries forming a quadrilateral green disc around the base of the superior ovary. The morphology and anatomy of the nectaries in Euonymus fortunei (Turcz.) Hand.-Mazz. and Euonymus europaeus L. flowers were analysed under a bright-field light microscope as well as stereoscopic and scanning electron microscopes. Photosynthetic nectaries devoid of the vascular tissue were found in both species. Nectar was exuded through typical nectarostomata (E. fortunei) or nectarostomata and secretory cell cuticle (E. europaeus). The nectaries of the examined species differed in their width and height, number of layers and thickness of secretory parenchyma, and the height of epidermal cells. Moreover, there were differences in the location and abundance of nectarostomata and the content of starch and phenolic compounds.
The aim of this statistical-morphological study was to compare several clustering techniques in order to identify the one that best differentiate the three Romanian linden species (Tilia spp., Tiliaceae), i.e. silver lime, large-leaved lime and small-leaved lime. Fifty individuals corresponding to each of the three species were sampled and eleven morphological twig, bud and leaf descriptors were assessed. Three sets of data, each of them being composed by a pair of two different species, were used. In all cases, Ward's Method (as amalgamation rule) and Percent disagreement (as distance measure) provided the best separation between the three pairs of linden species. The best separation, without any overlap, was observed in the case of large-leaved linden-silver linden pair. Similar separation pattern was also observed when all 150 individuals, corresponding to the three linden species were included in the analysis. In this case, silver lime-like individuals were clearly differentiated from the pair small-leaved lime and large-leaved lime. In conclusion, by using a wide variety of clustering combinations available within STATISTICA software, Ward's Method in combination with Percent disagreement proved to be the best choice for discriminating between the three linden species. In order to obtain better results, future research should include more lime stands across species' distribution ranges.
