Pollen Characters Research Articles

Pollen Morphology of Polygala L. (Polygalaceae) from Turkey and its Taxonomic Implications

Pollen morphology of Polygala taxa from the family Polygalaceae in Turkey is presented in this study. Pollen features of 18 species along with one undescribed species in the section Polygala were examined with light and scanning electron microscopy, 11 of which were studied and defined for the first time. Cluster analysis and principal components analysis were conducted to determine informative palynological characters and to discover similarities among the studied taxa. Based on qualitative and quantitative variables in the phenogram, the studied taxa were divided into three major clusters. Multivariate analyses revealed that apocolpium characters, including a psilate apocolpium, the presence of apocolpial lumens with granules and small depressions with psilate or rugulate walls are the most distinct features for discriminating Polygala taxa. Intraspecific variations in some pollen characters, such as the exine pattern and aperture membrane features, are reported for several taxa. Pollen morphological data obtained in the present study are compared with those from previous studies for a number of species, and the results are evaluated. In addition, the aperture number and its probable significance in the Turkish Polygala are considered for some taxa, with emphasis on their known pollination strategies.

Karakteristik Polen pada Spesies Mangrove di Kawasan Hutan Mangrove Batu Lumbang, Denpasar, Bali

The diversity of mangrove species in an area can be observed through morphological structure, anatomy, as well as palynology. Palynology is a study of pollen that frequently used as a reference to support data in identifying mangrove species. Mangrove areas in Bali have patchy distribution, one of which can be found in the Batu Lumbang area. Batu Lumbang is a mangrove area that is part of the Ngurah Rai Forest Park. Observation of the micromorphological characteristics of pollen in the Batu Lumbang mangrove forest area was carried out through the acetolysis method with modification. Eleven mangrove species were sampled, comprised of Aegiceras corniculatum, Avicennia marina, Bruguiera gymnorhiza, Ceriops tagal, Exoecaria agallocha, Lumnitzera racemosa, Rhizophora apiculata, Rhizophora mucronata, Sonneratia alba, Sonneratia caseolaris, and Xylocarpus granatum. The results of observations on pollen from eleven species of mangroves show similarities of pollennits, monads. In addition, other pollen characters such as aperture type, pollen shape, and pollen size categories found vary among the samples observed. These characters can also group several species that have the same family or genus. In turns, these can be used as diagnostic character to distinguish one species with another.

Does palynotaxonomy contribute to the systematics of the genus? The section Multicaulia of the genus Hedysarum (Fabaceae) example in Türkiye

The purpose of the current work was to assess the systematic and taxonomic significance of the pollen morphological characteristics of the Multicaulia section of Hedysarum species found throughout Türkiye using scanning electron microscopy (SEM) and light microscopy (LM) techniques. For this reason, seven different species currently classified in the Multicaulia section were collected from various localities. The pollen grains were nonacetolyzed, prepared and directly measured according to the Wodehouse method. Pollen grains were found to be subprolate in H. nitidum but prolate in others and the exine sculpturing pattern was determined to be microreticulate-perforate in six taxa while only H. varium subsp. syriacum had reticulate-perforate sculpture. The minimum exine thickness was measured at 0.96 μm in H. varium subsp. varium, while among the investigated species, H. nitidum had an exine measurement of 1.38 μm. In this study, multivariate analysis was used to investigate nine qualitative and quantitative features. Data cluster analysis revealed that the pollen characteristics were important in helping to distinguish the different species from one another. The results demonstrated that the genus Hedysarum of the section Multicaulia was divided into two major groups based on variations in pollen dimensions. The usefulness of certain pollen morphological traits was assessed, and the congruency of the palynomorphological investigations was examined. The findings demonstrated the significance of pollen micromorphology in precisely identifying and categorizing the Multicaulia section.

Pollen viability and longevity in Juniperus taxa native to Slovakia

Pollen viability, dispersion ability and longevity during deep-freezer storage were studied in three Juniperus taxa distributed in Slovakia. All these characteristics of pollen are closely related to the pollination and/or fertilization success of the junipers in nature. Pollen viability varied considerably between the three populations of J. communis and one population of each, J. sibirica and J. communis var. intermedia. Pollen germination rate ranged between 40.75% and 75.06%, and pollen tube length between 30.32 and 40.41 µm. A clear tendency indicates a higher germination rate of J. communis pollen from lower altitudes and reduced germination of J. sibirica and J. communis var. intermedia pollen from higher altitudes. The dispersion potential of the J. communis pollen during its shedding seems relatively low. In 2021, pollen cloud density was diluted at 68.1% at the 4 m distance from the test shrub, in 2022 of 52.1% at the 17 m distance from the pollen source. A deep-freezer storage of juniper pollen in a double-walled polyethylene bag with silica gel was not efficient enough, as indicated by the drop of pollen germination rate of 31.2% in J. communis and of 79.4% in J. sibirica during a 1-year storage period at − 81 °C.

Pollen morphology of Acanthoideae species from the Shivalik Foothills in Rajaji National Park (Uttarakhand, India).

Apart from its role in plant taxonomy, the understanding of pollen morphology is considered an essential interdisciplinary tool in diverse applied fields, including plant systematics, melissopalynology, aeropalynology, forensic palynology, paleopalynology, and copropalynology. In palynotaxonomy, it is frequently employed to classify and validate natural groups across a range of hierarchical levels, from higher categories down to the infrageneric level. The subfamily Acanthoideae, within the Acanthaceae family, consists of a diverse group of flowering plants that are distributed globally. The present study attempted a comprehensive analysis of the pollen morphology, employing both light microscopy (LM) and scanning electron microscopy (SEM), for a total of 13 Acanthoideae species from the Shivalik Foothills in Rajaji National Park (located in the northern Indian state of Uttarakhand, Western Himalaya). The findings indicated that the Acanthoideae is characterized by eurypalynous features, and the studied species exhibited pollen grains that were monads, radially symmetrical, and varied in size from small to large. The pollen grains were predominantly tricolporate or heteroaperturate, with porate occurrences being rare. The significant variation in exine sculpturing, including reticulate, coarsely reticulate, and bireticulate patterns, holds substantial taxonomic significance. The detailed presentation encompasses pollen morphological characters described with LM and SEM micrographs, along with a species-level identification key. RESEARCH HIGHLIGHTS: This article provides a thorough analysis of the pollen morphology of Acanthoideae taxa using both light microscopy and scanning electron microscopy, covering 13 species across 10 genera and revealing a broad spectrum of pollen characteristics, including size, shape, aperture type, and exine sculpturing. The microscopic investigation of these Acanthoideae species not only enhances our understanding of their pollen morphology but also aids in species identification through the development of a pollen-based key.

Pollen morphology of Norwegian hybrids of Sorbus

The genus Sorbus s.l. consists of small to medium‐sized trees primarily found in coastal areas, with three European hotspots of diversification: Fennoscandia, south‐east Europe and the British Isles. Taxonomic classification of Sorbus s.l. in Europe is still unresolved, and this study aims to address this issue by examining the pollen morphology of various Sorbus hybrids. Pollen morphology of 16 specimens from 13 species of Sorbus s.str., Aria and Hedlundia, some of them common, others are endemic and listed as threatened species, were studied. Measurements of the polar and equatorial axis of all pollen grains show that there are variations in pollen size and shape among different hybrids, with a correlation between ploidy levels and the equatorial diameter of the pollen. Surface structures of the pollen were observed using SEM. Principal component analysis (PCA) was performed to analyze the pollen characters, and the results show that it is possible to separate Aria from Sorbus and Hedlundia based on the length of the polar axis of the pollen grain, while the number of perforations is important for classification within Hedlundia. The study concludes that pollen morphology can be a useful tool for distinguishing between different Sorbus hybrids and can thus aid in understanding their past distributions.

The Study of the Pollen Grains of Various Species Belonging to the Genus Cousinia Cass. (Asteraceae) in Iraq

The genus Cuosinia Cass. is among the most common genera within the Asteraceae family. This genus contains an approximate range of 500 to 600 taxa. Pollen morphology analysis has proven to be a significant tool in the categorization of the Asteraceae, in addition to helping in the classification of specific genera and species under the family. An extensive examination of the pollen morphological features of six species belonging to the Cuosinia genus was carried out using both light and scanning electron microscopy. The pollen features that are beneficial for distinguishing various species of Cousinia based on characteristics instance form, dimension of the polar diameter and equatorial diameter, polar to equatorial axis ratio (P/E), exine thickness, sculpturing, and quantity of verrucae. Examination using light microscopy revealed that pollen grains were monads, tricolporate, isopolar, prolate-spheroidal, prolate, Sub-prolate. Using scanning electron microscopy, we categorized the pollen grains into three groups based on their exine ornamentation: group I (densely verrucate), group II (verrucate), and group III (loosely verrucate). Micrographs illustrating the morphology of pollen grains are accompanied by comprehensive descriptions of their structural characteristics. The pollen traits, such as morphology, exine thickness, and surfaces sculpturing, were found to be highly useful for classifying purposes.

Investigating the effect of postharvest conditions on the microbial quality and physicochemical characteristics of bee pollen

Considering the scarcity of information on postharvest management of bee pollen, especially its fresh form, this study aims to investigate the effect of storage conditions and duration on the microbial load of fresh and dried pollen, while also considering changes in physicochemical parameters. Specifically, microbiological analyses were applied to record the growth of Mesophilic Total Viable Counts (MTVC), Yeasts & Moulds (Y&M), Enterobacteriaceae (ENT), Lactic Acid Bacteria (LAB), and Escherichia coli. The results showed that fresh pollen can be stored in the freezer (-18 °C) for one year, without exceeding the legislative limits for the studied pathogens, as after storing for 12 months, the mean counts of MTVC, Y&M, ENT, and LAB were 3.93, 4.04, 1.71, and 2.82 log cfu/g, respectively, whereas moisture, protein and lipid content, fatty acid composition, and colour remained unchanged. When fresh pollen was stored at 4 °C, over a six-month period, the MTVC & ENT counts were out of limits, and changes were observed in colour, total lipid content (32.18% decrease), and fatty acid composition (31.68% for C18:2 and 21.56% for C18:3 reduction, 31.5% increase for C18:0). Finally, storing fresh pollen at 25 °C is deemed insufficient for maintaining quality characteristics. Dried pollen demonstrated better results, compared to fresh pollen, maintaining values of microbial load within legislative limits at all storage temperatures, thus making long-term storage easier. The data gathered during this study may form the basis for a guide including proper beekeeping practices and postharvest bee pollen treatment and management, contributing to the optimization of pollen production.

Botanical Originand Extraction Methods of Philippine Stingless Bee (Tetragonula biroiFriese) Pollen and its Food Functionality: Phenolic and Flavonoid Content and Antioxidant Activity

With its high nutritional and bioactive content, bee pollen is recognized as a functional food. However, its composition is highly dependent on a range of factors, such as geographical location. In this research, we used DPPH to determine the antioxidant activity of several stingless bee (Tetragonula biroi) pollen samples sourced from five different areas in the Philippines and compare their phenolic and flavonoid content. Additionally, we compared two extraction methods: maceration (or soaking of samples) for three days and sonication for 30 minutes. Interestingly, our findings show that the phenolic content of bee pollen is weakly associated with antioxidant activity, indicating that other bioactive chemicals may play a more significant part in the antioxidant characteristics of bee pollen. Antioxidant properties based on the DPPH assay of pollen harvested from Calamba are higher compared to other samples from different geographic areas, i.e., Quezon Province, Sorsogon, Laguna, and Albay. When compared to the maceration approach, extracts generated from the sonication process had lower antioxidant activity. These findings suggest that Philippine stingless bee pollen is a potential source of bioactive compounds, and the choice of extraction method and geographic source are significant factors affecting its antioxidant activity.

Pollen variability in species of Dioscorea L. (Dioscoreaceae)

Dioscoreaceae is characterised by wide morphological variability, including hermaphrodite genera such as Tacca J.R.Forst. et G.Forst, Trichopus Gaertn., and Stenomeris Planch. and some dioecious species in the genus Dioscorea L. This study aimed to describe the pollen characters of 81 species of Dioscorea occurring in Brazil, contributing to a broader knowledge of Dioscoreaceae by investigating the possibility of using pollen attributes in taxonomic classification. Pollen grains were treated by lactic acetolysis, measured, described, and photomicrographed. The results were subjected to statistical analysis. Unacetolysed pollen grains were mounted on stubs with carbon tape for scanning electron microscopy. Our results showed that the studied species have heteropolar pollen grains, ranging from small to medium, with mainly elliptical, circular, and triangular ambs. Pollen grains with 1, 2, or 1‒2 apertures were recorded in most species, as well as nine types of sexine ornamentation (perforate in 23 species, striate in 23 species, microreticulate in 15 species, reticulate in eight species, rugulate in seven species, bireticulate in two species, rugulate-verrucate in one species, cristate in one species, and gemmate in one species). The sexine had striae in different shapes and directions. Micromorphological results of pollen characters were of great importance for species delimitation. The findings reported herein demonstrate that palynological analysis can provide valuable information to improve taxonomic classification and contribute to a more robust phylogenetic representation of the genus.

Palynological studies of some species of the genus Cuscuta with emphasis on taxonomy

The main objective of this research was to conduct a comparative pollen morphological analysis of some representatives of the genus Cuscuta in relation to taxonomy. Investigations of 38 species and 1 variation revealed that not only the number, but the colpi length, as well as the exine ornamentation (at the SEM level), can be regarded as a diagnostic feature. For all the taxa studied, the common zonocolpate type of pollen was observed, represented by three variations: I) colpi long; II) colpi of medium length; III) colpi short. In combination with colpi length, variations in the number of colpi were also identified, such as: I) 3(4)-zonocolpate pollen grains with long colpi (in most of the species studied from subgenera Grammica and Cuscuta, as well as in C. monogyna from the subgenus Monogynella); II) 4(3)-zonocolpate pollen grains, with long colpi (C. cristata from subgenus Grammica); III) 3-zonocolpate pollen grains both with long colpi and colpi of medium length (C. abyssinica from subgenus Cuscuta and C. africana, C. angulata from subgenus Pachystigma); IV) 3-zonocolpate pollen grains with colpi of medium length were noted for species from all four subgenera (C. cassytoides, C. lupuliformis from subgenus Monogynella, C. kotschyana from subgenus Cuscuta, C. nitida from subgenus Pachystigma and C. jalapensis, C. rostrata, C. suaveolens from subgenus Grammica); V) 3–4- or 4-zonocolpate, with short colpi (C. lehmanniana and C. gigantea from subgenus Monogynella respectively); VI) 5–6-zonocolpate, with short colpi (C. reflexa from subgenus Monogynella). Using SEM, three main types of exine ornamentation were also identified: perforate, foveolate and reticulate. The last type in the vast majority of the cases was presented in combination with echinae (rarely with spines or granules). The data revealed that the presence of the significant similarity of palyno-morphological characteristics in representatives of the subgenera Cuscuta, Pachystigma and Grammica, with the exception of the species Lepidanche adpressa (syn. C. compacta), makes it difficult to create an identification key at the level of individual subgenera. Pollen features can be most clearly used only to distinguish the subgenus Monoginella, reflecting its certain isolation within the entire Cuscuta genus. The presence of a highly specialized reticulate exine ornamentation in Lepidanche adpressa (syn. C. compacta), not identified for the pollen of any of the studied taxa of the subgenus Grammica, indicates a significant proximity of this species to the subgenus Monogynella. For the species C. reflexa, the obtained palyno-morphological data are consistent with the previous opinion about the separation of this species, as well as its more advanced position within the genus Cuscuta.

Dynamics and characteristics of allergenic plant pollen in the Republic of Uzbekistan

The article describes the quantitative and qualitative indicators of more than twenty allergenic plant pollens in the city of Samarkand. In addition, information on the morphological microscopic structure of plant pollen collected from the urban area is given. As a result of research, in the city of Samarkand Cupressaceae, Chenopodiaceae, Salicaceae, Fagaceae. It was found that there are many allergenic species in family representatives.

Flowering phenology and pollen characteristics of cultivated populations of Paeonia ostii ‘Feng dan’ at different altitudes

Flowering phenology and pollen characteristics of cultivated populations of Paeonia ostii ‘Feng dan’ at different altitudes

Karakterisasi dan Potensi Ekstrak Daun Paitan (Tithonia diversifolia) sebagai Penolak Nyamuk Aedes aegypti

The paitan plant (Tithonia diversifolia) contains alkaloids, saponins, flavonoids, tannins and phenolics which have the potential to prevent Dengue Hemorrhagic Fever (DHF). This plant also has various insecticidal activities. In society, there are many mentions of the paitan plant, so people need to know the characteristics of this paitan plant. The aim of this research is to determine the morphological characterization and specific fragments of the paitan plant, as well as to determine the activity and effective concentration of the ethanol extract of paitan leaves as a repellent for the Aedes aegypti mosquito. Two types of methods were used, namely descriptive qualitative for observing morphology, specific fragments, pollen, and phytochemical screening, and experimental methods for mosquito repellent testing, and calculating the protective power of the ethanol extract of paitan leaves. The results obtained are flowers consisting of two shapes, namely ribbon flowers in the outer circle, infertile, and tube shapes in the inner circle. Stomata are anomocytic type, while trichomes are non-glandular multicellular type. Pollen characteristics, namely small size, colpate, number 3, aperture shaped trizonocolpate with echinate ornamentation. The screening results for the ethanol extract of paitan leaves were positive for containing metabolite compounds, such as flavonoids, alkaloids, tannins, saponins, terpenoids and phenolics. The results of the mosquito repellent test showed that the higher the concentration of the extract, the fewer mosquitoes that landed. Calculation of protective power shows that the most effective concentration in repelling mosquitoes is 15%, namely 93.64%. The conclusion is that paitan (Tithonia diversifolia) leaf extract has potential activity as a repellent against Aedes aegypti mosquitoes with the most effective concentration being 15%.

MOLECULAR AND MORPHOLOGICAL ANALYSIS SUPPORTS THE TRANSFER OF THE MONOTYPIC INDONESIAN GENUS SEPTOGARCINIA KOSTERM. TO GARCINIA (CLUSIACEAE)

Based on molecular phylogenetic analysis and an assessment of fruit and pollen characters, the transfer of Septogarcinia sumbawaensis Kosterm., endemic to Sumbawa Island, Indonesia and the sole member of the genus Septogarcinia, to Garcinia is strongly supported. The formal transfer of S. sumbawaensis to Garcinia (as G. sumbawaensis; the current name is G. septogarcinia) was based on morphological studies only. Phylogenetic analysis of nuclear internal transcribed spacer (ITS) sequences supports a placement of G. septogarcinia in Garcinia Section Brindonia. The distinctive dehiscent fruit, cited by Kostermans as justification for erecting Septogarcinia, is interpreted as an autapomorphy for this species in Garcinia. Pollen exine ornamentation is similar to G. griffithii, G. gummigutta var. gummi-gutta, G. mestonii, Garcinia sp. (Maluku) and Garcinia sp. (Batulanteh, Sumbawa).

Physicochemical characteristics of bee pollen collected from Virovitica-Podravina County

Pollen grains are located on the anthers of the flowers, bees collect them and mix them with secretions from their salivary glands and nectar and carry them to the hives in the baskets situated on their hind legs. According to the chemical composition, bee pollen is a mixture of proteins, fats, carbohydrates, vitamins and other useful substances for the development of bees in the hive. Due to its nutritional value and potential healthful properties, it is valuable product for beekeeper’s income. The aim of this research was to evaluate the physicochemical characteristics of bee pollen in relation to the period of collection and geographical origin from different localities in Virovitica-Podravina County. Eleven bee pollen samples were collected from stationary apiaries in the period of April and May 2022.Palynological analysis showed that dominated pollen in five samples was pollen from Brassica sp.; Malus spp. and Salix spp. pollen dominate in two bee pollen samples while two samples had dominating pollen coming from Asteraceae family. Physicochemical analysis showed that pollen collected in the period of April had a lower proportion of ash, total fat and phenols, but a higher proportion of moisture content, proteins and carbohydrates.

Revealing the intricate microcosm: Advancing invasive species pollen analysis through scanning microscopy of ultra sculpture.

Micromorphological visualization of plant surface peculiarities provides valuable characters for the precise identification of plant species. Invasive alien species, introduced outside their native range, pose significant ecological, and health challenges. This study focuses on micromorphological investigations of selected invasive plant species belonging to the families Amaranthaceae, Asteraceae, Moraceae, Crassulaceae, Cannabaceae, Fabaceae, Commelinaceae, and Oxalidaceae. The study employs scanning electron microscopy (SEM) to analyze the species micromorphology of pollen structure in depth to characterize the sculpturing patterns. Additionally, the study examines the pollen characteristics of these invasive plants, including shape, size, and fertility, along with exine sculpturing. The maximum polar diameter was observed for Senna tora (41.2 μm). The spines in Achillea fragrantissima were measured to have dimensions of approximately 1.91 μm in length and 2.11 μm in width. The findings shed light on the allergy-causing potential of these invasive species, providing crucial information for accurate identification and effective management strategies to safeguard the indigenous flora of the region. The study contributes to the knowledge base for botanists, taxonomists, policy makers, climate experts, and biodiversity specialists. RESEARCH HIGHLIGHTS: Integrating SEM to analyze the pollen of invasive species. Unveiling pollen micromorphology of invasive species. Exploring the microscopic realm of invasive pollen to accurately identify the species.

Deep learning approaches to the phylogenetic placement of extinct pollen morphotypes.

The phylogenetic interpretation of pollen morphology is limited by our inability to recognize the evolutionary history embedded in pollen features. Deep learning offers tools for connecting morphology to phylogeny. Using neural networks, we developed an explicitly phylogenetic toolkit for analyzing the overall shape, internal structure, and texture of a pollen grain. Our analysis pipeline determines whether testing specimens are from known species based on uncertainty estimates. Features from specimens with uncertain taxonomy are passed to a multilayer perceptron network trained to transform these features into predicted phylogenetic distances from known taxa. We used these predicted distances to place specimens in a phylogeny using Bayesian inference. We trained and evaluated our models using optical superresolution micrographs of 30 extant Podocarpus species. We then used trained models to place nine fossil Podocarpidites specimens within the phylogeny. In doing so, we demonstrate that the phylogenetic history encoded in pollen morphology can be recognized by neural networks and that deep-learned features can be used in phylogenetic placement. Our approach makes extinction and speciation events that would otherwise be masked by the limited taxonomic resolution of the fossil pollen record visible to palynological analysis.

The nuclear DNA content, ploidy, and chromosome numbers in some species of Nitraria and associations with pollen characteristics

The nuclear DNA content, ploidy, and chromosome numbers in some species of Nitraria and associations with pollen characteristics

Studies of the pollen characteristics and the taxonomic significance of Impatiens from the Yunnan–Guizhou Plateau

ABSTRACT Impatiens is rich in germplasm resources, with more than 260 species in China. A study on the pollen micromorphology of Impatiens by scanning electron microscopy (SEM) showed that the pollen characteristics were richly diverse, and there was some correlation among the characteristics. In addition, the micromorphological index can be used for an effective cluster analysis of Impatiens. However, there was high interspecific similarity in some Impatiens, and the classification of Impatiens cannot be accurate to the species using pollen characteristics. Based on the classification conditions of Impatiens, the characteristics of the pollen structure were found to be useful to classify Impatiens into subgenera or smaller groups. The macroscopic characteristics and the number of sepals (NS) were used as references, which enabled the conclusion that there were 11 indices in the pollen micromorphological index, and the taxonomic effect was greater than the NS. In summary, the pollen micromorphology of Impatiens plays an important role in the classification of Impatiens. The purpose of this study was to explore this characteristic of Impatiens, which has some reference significance to supplement the pollen characteristics and palynological classification of Impatiens. The goal for this research was to aid in the interspecific identification and genetic breeding of Impatiens.