Exine Thickness Research Articles

Taxonomic insights into medicinal plants pollen, using advanced microscopy techniques, from the Western Ghats, India

Pollen morphological study on 18 medicinal plants from the Western Ghats (India) was carried out using light microscopy (LM), confocal laser scanning microscopy (CLSM) and field emission scanning electron microscopy (FESEM) techniques. The principal aim was to obtain high-resolution three-dimensional images and ultra-structure of the pollen grains of the studied taxa. The palyno-morphological characters, such as polar axis, equatorial diameter, P/E ratio, pollen shape, aperture type and number, exine thickness and surface ornamentation will be useful in the identification and taxonomic classification of the studied medicinal plants. Statistical analysis reveals grouping of the taxa in three different clusters and also isolated presence of taxa on the principal component analysis (PCA) biplot, irrespective of their families, showing similarities and/or variations among the studied taxa, belonging to the same and/or different families. The present study has taxonomic significance, providing high taxonomic resolution (identification of the taxa up to species level), and further aid in the identification and delimitation of the 18 studied plants.

Palynological characterization of succulents of the families Asphodelaceae and Asteraceae

This study aimed to analyze palynologically succulent species: Asphodelaceae: Haworthia chloracantha Haw., Haworthia cymbiformis (Haw.) Duval, Haworthia limifolia (=Haworthiopsis limifolia) Marloth and Asteraceae: Othonna capensis LH Bailey and Senecio peregrinus Griseb. Closed buds were preserved in acetic acid, the acetolyzed grains were arranged on microscope slides, and 50 pollen grains of each species were photographed. Using light optical microscopy, measurements were made of each grain in the polar and equatorial views, in micrometers (µm). For scanning electron microscopy (SEM), the anthers were macerated on microscope slides to release the grains, which were metallized with gold-palladium and photographed. In Asphodelaceae, the grains are monads, monosulcate, medium to large in size, elliptical in scope, bilaterally symmetric, heteropolar, with foveolate, ornamentation microreticulate, perforated, mean exine thickness 1.98-1.42-2.21 micrometers. In Asteraceae, the grains are monads, tricolporate, medium in size, circular to subcircular in scope, radially symmetric, isopolar, oblate-spheroidal and prolate-spheroidal in shape, with perforated echinate ornamentation, average exine thickness 4.08-4.41 micrometers. The pattern of the grains of Haworthia are in line with literature of Asphodelaceae, although the verrucate exine was not observed in this study. For Othonna and Senecio, the echinate ornamentation and thicker exine are in line with the pattern of the Asteraceae.

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.

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.

Exploring microscopic pollen morphology in herbaceous Flora: Insights and analysis using scanning electron microscopy.

Microscopic techniques can be applied to solve taxonomic problems in the field of plant systematic and are extremely versatile in nature. This study was focused on the new approaches to visualizing the imaging, tool to cover the micro-structural techniques applied to the pollen study of flowers. The current research was proposed to evaluate microscopic pollen morphological attributes using light and scanning electron microscopy of herbaceous flora from Samarkand, Uzbekistan. A total of 13 herbaceous species, classified into 11 different families were collected, pressed, and identified, and then acetolyzed their pollen to visualize under light and scanning electron microscopy. Herbaceous flora can be characterized by small to very large-sized pollen morphotypes presenting four types of pollen shapes, prolate spheroidal (six species), spheroidal (three species) and prolate and oblate (two species each). The polar diameter and equatorial distance were calculated maximum in Hibiscus syriacus 110.55 and 111.2 μm respectively. Pollen of six different types was found namely tricolporate pollen observed in seven species, tricolpate and pantoporate in two species each, sulcate in Gagea olgae and hexacolpate pollen was examined in Salvia rosmarinus. Exine ornamentation of pollen was examined tectate perforate, verrucate-reticulate, micro-reticulate, reticulate, reticulate-cristatum, gemmate-echinate, echinate-perforate, perforate-striate, rugulate, rugulate-striate, bi-reticulate, reticulate-perforate and perforate-micro-reticulate showing great variations. Exine thickness was noted highest for Rosa canina 2.9 μm and minimum in Punica granatum 0.65 μm. This study of pollen imaging visualization of herbaceous flora contributes to the opportunity for the taxonomic evaluation of and fills knowledge gaps in studies of herbaceous flora identification using classical microscopic taxonomic tools for their accurate identification. RESEARCH HIGHLIGHTS: Pollen in unexplored herbaceous flora of the Samarkand region was studied with light and scanning electron microscopic pollen study. There is a high variation in observed pollen micromorphological characters. Pollen microscopic morphology has important taxonomic value for the identification of herbaceous species.

Micrometer insights into Nepeta genus: Pollen micromorphology unveiled

This study provides a comprehensive pollen micromorphology within the Nepeta genus, revealing intricate details about the pollen grains' structure and characteristics. The findings shed light on the evolutionary and taxonomical aspects of this plant genus, offering valuable insights for botanists and researchers studying Nepeta species. The pollen grains of 18 Nepeta species were studied using scanning electron microscopy (SEM) and light microscopy (LM) in Northern Pakistan. At the microscale, pollen quantitative measurements, qualitative traits, and diverse sculpturing patterns were reported and compared. Significant differences in pollen size, shape, ornamentation, and sculpturing patterns were discovered among the Nepeta species. Our data show that exine sculpturing is quite diverse, with most species exhibiting a reticulate perforate pollen pattern. Nepeta connata, Nepeta discolor, Nepeta elliptica, revealed a distinct bireticulate perforate exine stratification. Hexazonocolpate pollen is the most common. Furthermore, the surface membrane attributes of the colpus varied greatly, ranging from rough, scabrate, psilate, to sinuate patterns. Principal Component Analysis (PCA) was used to discover the key factors influencing pollen diversity. PCA results showed that polar and equatorial diameters, colpi size, and exine thickness were the most influential pollen features between Nepeta species. This study adds to our understanding of pollen morphology in the Nepeta genus, offering information on the vast range of characteristics found in this economically important group. The extensive characterization of pollen features provides useful insights for the categorization and differentiation of Nepeta species, adding to the Lamiaceae micromorphology.

Evolution of pollen grain morphology in Amorimia and allies evidences the importance of palynological apomorphies and homoplasies in Malpighiaceae systematics

Background and aims – Pollen grain morphology is an important morphological character for aiding the systematics of flowering plants. For Malpighiaceae, only a single unpublished palynological study has comprehensively sampled ca 60 of this family’s 75 currently accepted genera. To test the systematic relevance of pollen morphology in Amorimia and allies, we characterised the pollen morphology of these lineages. We scored, coded, and mapped 12 characters onto the most recent molecular phylogeny of Amorimia and allies. Material and methods – We sampled 13 species of Amorimia as ingroup and two species of Mascagnia and Ectopopterys soejartoi as outgroup. Pollen grains were acetolised, characterised, and measured using light microscopy and scanning electron microscopy. Pollen quantitative measurements were submitted to a PCA multivariate analysis. Additionally, quantitative and qualitative characters were scored and coded into 12 characters and mapped onto the molecular phylogeny of Amorimia and allies. Key results – Amorimia and allies are stenopalynous due to all species showing the same pollen type, with some subtle differences between the pollen grains, such as details of ornamentation, shape, size, and thickness of the pollen exine. However, the patterns of pollen grain evolution showed that few qualitative and apomorphic characters are informative for intrageneric distinction (i.e. type and number of apertures), and almost all quantitative and homoplastic characters analysed were informative at infrageneric levels within Malpighiaceae. Conclusion – Our results demonstrate that even though the pollen morphology characters of Amorimia and allies show subtle variation, both qualitative and quantitative apomorphic and/or homoplastic characters are highly informative for intra- and infrageneric levels in Malpighiaceae when analysed in a phylogenetic context.

PALYNOLOGICAL DIVERSITY OF POLLEN MORPHOLOGY IN ENDEMIC NORTHERN IRAQI HYPERICUM SPECIES (HYPERICACEAE)

The presented research investigated the pollen morphology of endemic Iraqi Hypericum species. The study revealed phenotypic features of pollen grains in the polar and equatorial views and their quantitative and qualitative characteristics. The results showed that the pollen grains of the genus Hypericum were radially symmetrical and isopolar, and their apertures were simple and tricolporate, except the species H. davisii, distinguished as tetracolprate. Dividing the studied species based on pollen grain sizes comprised two groups. Small pollen grains with an average length of the equatorial view ranged between 10–16 μm in H. lysimachioides and H. vermiculare. Medium-sized pollen grains with an average extent between 17–26 μm emerged in the species, i.e., H. retusum, H. triquetrifolium, H. perforatum, H. lydium, H. tetrapterum, H. asperulium, H. scabrum, and H. davisii. Pollen grains, also divided according to the P/E ratio, had two main groups. The pollen grains were subprolate and spherical, with the exine sculpturing examined by a scanning electron microscope (SEM), and isolated into four groups: 1) microreticulate reticulum, including H. asperulium, H. lydium, and H. vermiculare, 2) perforate, i.e., H. retusum, H. scabrum, H. tetrapterum, and H. triquetrifolium, 3) psilate with H. perforatum and H. davisii, 4) and reticulate exine sculpturing in H. lysimachioides, all isolated from the rest of the species. SEM images showed the thickness of exine ranged from 0.5 to 2 μm. The topical study also added H. davisii as a new species with no previous records in Iraq. This pollen study added valuable data for taxonomy and suggested that it should proceed with its first-time registration in Iraq. The pertinent research could provide a taxonomical key for Hypericum species in Iraq.

Effects of Fabaceae and Poaceae Pollen Accessibility and Traits on the Pollinivory of Adult Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae).

Pollen is a food source for adult Chrysoperla externa(Hagen), whose larvae are biocontrol agents against pests. However, adults may face challenges in foraging for pollen due to differences in pollen accessibility and variability in pollen morphology and chemistry. In the laboratory, we investigated the ability of adult C. externa to consume pollen from flowers of Cajanus cajan, Canavalia ensiformis, Crotalaria juncea, Flemingia macrophylla, Avena strigosa, Pennisetum glaucum, Sorghum bicolor, and Zea mays, and we explored whether adults chose any of these pollens based on their quantitative and qualitative features. Cajanus cajan and F. macrophylla pollen were the only ones not consumed by adults when confined to flowers. Pollen removed from the preanthesis buds was offered simultaneously for 24 and 48h. In both periods, adults consumed more of the medium-sized P. glaucum (with the second largest exine thickness) and large-sized Z. mays (with the thinnest exine) pollen, even though they had significantly less crude protein than Fabaceae pollen, whose sizes varied from medium (C. juncea, with the thickest exine) to large (C. ensiformis, whose exine thickness was equal to that of P. glaucum). Overall, adults consumed more Poaceae pollen than Fabaceae pollen, but the palynological features and the protein contents did not affect this choice. Our results highlighted that C. juncea, P. glaucum, S. bicolor and Z. mays are good pollen sources for adult C. externa and should be considered promising candidates in the selection of insectary plants to deploy in biocontrol programs aimed at the conservation of this lacewing.

Pollen morphology of Doronicum L. (Asteraceae: Senecioneae) from Turkey and its taxonomical implications

The main purpose of this study is the palynological characterization of Doronicum L. taxa that occur naturally in Turkey. In this context, the pollen morphology of 11 species and one subspecies of Doronicum was researched in detail by light microscopy and scanning electron microscopy (SEM). Furthermore, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were carried out to identify closely related species and palynological characters that could potentially be used to distinguish the studied taxa. Pollen grains were found to be isopolar monad and tricolporate. Pollen were prolate-spheroidal in shape, with a circular amb. SEM showed the exine ornamentation was echinate-perforate. Differences in the bases and ends of the spines were observed; therefore, pollen grains were categorized based on spine morphology. Three components of the studied palynological characteristics were determined with PCA. The PCA results explained 78.79% of the variation, and polar diameter, equatorial diameter, diameter in polar view, exine thickness, intine thickness, pore length, colpus width, and spine length were found to be the most valuable palynological characteristics for discrimination of the Doronicum taxa. The HCA dendrogram also revealed three main clusters. This study is helpful for understanding the relationships among the taxa of Doronicum and provides insight for future taxonomic research.

Pollen morphology and variability among the wild Cannabis sativa L. from the western Himalaya, India

The present study aimed to examine the intraspecific variation in pollen traits of genus Cannabis from Western Himalaya, India. A total of 1650 pollen grains from 55 accessions collected from an altitudinal range between 259 and 2751 m a.s.l from the western Himalayas, India were analyzed by (LM) light microscopy and (SEM) Scanning Electron Microscopy. Six quantitative characters, i.e., length of the polar axis (P), length of equatorial axis (E), exine thickness (Ex), number of granules (Ng), pore diameter (Pd), and P/E ratio were studied. Pollen grains of maximum accessions were tricolpate while pollen grains of three accessions i.e., CAN17, CAN25 and CAN31 were tetraporate. Majority of the pollen grains were prolate spheroidal (83.64%) whereas 1.82% was spheroidal. PCA indicated that the first four components account for 69.9% of the total variability. PC1 attribute 34.41% of the variability with equatorial diameter being the significant variable, whereas PC2 contributed 19.57% variability having length of polar axis (P) and shape class (P/E) as the significant variables. PC3 contributed 20.1% of the total variability with PE and number of granules being the significant variables. Pollen size, aperture number, and surface ornamentation may prove useful in species discrimination. This current study gives a first-hand report on the palynological variation of wild Cannabis populations of the Western Himalaya, India.

Pollen morphology of endemic Linum species (Linoideae: Linaceae) from Mexico

The morphological characteristics of pollen grains of Linum species in Mexico have not previously been evaluated in quantitative terms. This study reports statistical values of pollen characteristics – polar axis, equatorial axis, shape, polar area, exine thickness, sexine thickness, nexine thickness, and height and diameter of ornamental pollen elements – of 11 of the 13 endemic species accepted to date and for which material was available: L. cruciata, L. flagellare, L. lasiocarpum, L. longipes, L. mexicanum, L. modestum, L. orizabae, L. pringlei, L. rzedowskii, L. scabrellum, and L. tenellum. The detailed light and scanning electron microscopy study revealed that the pollen is prolate-spheroidal to subprolate, tricolpate and with semitectate exine sculptured with bacula, clavae, gemmae or spines whose height and diameter follow a homogeneous, intermediate, or heterogeneous pattern. The principal component analysis found that five characters, namely the height of the ornamental elements, sexine thickness, exine thickness, diameter of ornamental elements, and nexine thickness, explained the highest percentage of the variance between species. The cluster and discriminant analyses classified some of the species into three groups and differentiated three of them according to their morphology. The difficulty in distinguishing some species through a conventional approach was solved conveniently using palynological traits since the ornamentation pattern of pollen grains was unique and because grains of various species were statistically different, thus representing a tool for identifying Linum species.

Pollen morphology of Scorzonera s.l. (Asteraceae, Cichorieae, Scorzonerinae) occurring in Iran

Pollen characters of 48 species of Scorzonera s.l. distributed in Iran were investigated by using light and scanning electron microscopy. The pollen grains are isopolar, radially symmetric, generally 3-zonocolporate, rarely 2-colpororate or 4-colporate. The pollen grains are oblate-spheroidal in shape (P/E=0.89 to 0.99) with the polar axes 37.1–58.1 µm and the equatorial axes 38.8–60.6 µm. We adopted the four pollen types recognized by Blackmore based on the number and position of their lacunae. For the first time, some pollen grains of S. longipapposa and S. tortuosissima were shown to have 26 (24+2) lacunae. We compared pollen morphological characters with the findings of the most recent systematic treatment. Type A with 6 lacunae was observed in Takhtajaniantha pusilla and S. parviflora, type B with 18 lacunae in Gelasia, type C with 20 lacunae in Pseudopodospermum and type D with 24 lacunae in Ramaliella, S. renzii and the Podospermum clade (except S. laciniata) in Scorzonera. We also observed 15 or 18 lacunae in S. rupicola. The pollen in Scorzonera appears to evolve toward reduction of spines in S. parviflora, extension of spines in the Podospermum clade, enlargement of the space between ridges and increase in the number of lacunae (S. longipapposa and S. tortuosissima). 26 pollen characters of the examined species were analysed by UPGMA and PCA. Pollen size, spine size, distance between spines, number and arrangement of spines between two equatorail lacunae, exine thickness, spine length/P or E, dimensions of lacunae and polar area were shown to contribute significantly to understanding the morphology of Scorzonera.

Pollen morphology of family Thymelaeaceae Juss. in India and its taxonomic implications

We provide pollen morphology and ultrastructure of 26 plant taxa, comprising 14 genera, 21 species, 1 sub-species and 3 varieties, of the Thymelaeaceae family from the Indian sub-continent using light micsoscopic (LM) and scanning electron microscopic (SEM) techniques. The principal aim was to provide new and useful information regarding the extent of the pollen morphological diversity among the Thymelaeaceae taxa and, thus, contribute to a better understanding of the taxonomy of the studied taxa. The pollen grains of the studied taxa are essentially radially symmetrical, apolar, (released as) monad, pantoporate with a typical crotonoid pattern, and spheroidal (mostly) in shape; but widespread variations with respect to the number and dispensation of pores, size, exine (ectoexine and endoexine) thickness, and the shape itself (spheroidal, sub-spheroidal and prolate spheroidal), as well as in the amb (outline) have been also recorded. Pollen identification keys, based on the pollen micro-morphological attributes, were also constructed in order to easily identify the 26 studied Thymelaeceae taxa up to species and/or varieties level (high taxonomic resolution, showing taxonomic significance). The pollen morphological attributes of the 26 studied plant taxa of the Thymelaeaceae family were subjected to Principal Component Analysis (PCA) and Hierarchical Component Analysis (HCA), which suggest four clusters. The cophenetic correlation coefficient also validates the four group of clustering. The study will significantly help in the precise pollen identification in fossil (pollen) records for the reconstruction of vegetation dynamics and contemporary climate change during the Quaternary Period in India. Moreover, the present study also helps in determining the phylogenetic and evolutionary trend on the basis of the presence or absence of exine ornamentation and having more or less apertures among the pollen grains of the 26 studied Thymelaeaceae taxa.

How Do Pollen Grains of Convallaria majalis L. Respond to Different Habitat Conditions?

To date, the effect of habitat conditions on the characteristics of pollen has not been extensively investigated; however, it needs to be remembered that it may be highly significant for the quality of their generative reproduction success. It was decided to conduct the analyses on Convallaria majalis as a common species, naturally found in many different forest habitats. Moreover, the investigations covered pollen morphology and for the first time also the variability of pollen grains in this species. The plant material came from 98 natural sites located in Poland, in nine differing forest habitats. In total, 2940 pollen grains were analyzed in terms of five quantitative features (i.e., the length of the longest and shortest polar axes–LA and SA, exine thickness–Ex, the LA/SA and Ex/LA ratios) as well as the following qualitative ones: pollen outline and shape, sulcus type and exine ornamentation. Our studies revealed that the most important pollen characteristics in C. majalis included sulcus type, exine ornamentation, distribution and size of perforations, LA and pollen shape. The study showed the response of pollen to different habitat conditions found in the nine investigated habitats. The Ex/LA ratio and Ex were these pollen characteristics, which exhibited the most marked response to the different habitat conditions. Pollen from two habitats, moist mixed coniferous forest and upland mesic broadleaved forest, exhibited the most distinct characteristics.

The effect of herbicides on morphological features of pollen grains in Prunus serotina Ehrh. in the context of elimination of this invasive species from European forests

Prunus serotina Ehrh. is an alien invasive neophyte widespread in European forests. So far, no effective methods of its elimination have been developed. For this reason, the aim of our study was to determine how herbicides affect the morphological characteristics of pollen grains. This knowledge may be crucial to control this invasive species. The current study was carried out in a research area of 2.7 ha located in the Zielonka Forest near Poznań, Poland (N 52°31′58.016″, E 17°05′55.588″). We tested morphological differences among ten features of P. serotina pollen, based on the samples collected from 15 control trees compared to the 50 trees treated with five different herbicides. In total 1950 pollen grains were measured. We confirmed the adopted hypotheses of long-term herbicide influence on P. serotina pollen. Pollen grains from the control trees had a longer equatorial axis, were more elongated in shape and had the largest range of exine thickness compared to the pollen from the herbicide-treated samples. Exine thickness in the control sample was on average 0.74 µm, ranging from 0.42 to 1.19 µm. The average values and the ranges of this trait in the samples treated with herbicides were larger (e.g. average exine thickness was from 0.90 to 0.95 µm). There were differences in the P/E ranges of variability between the control and herbicide-treated samples. In the control sample the P/E ratio was 1.32–2.04 and elongated forms of pollen shapes prevailed, while in the herbicide-treated samples it ranged from 1.03 to 1.47. The share of deformed pollen grains in the herbicide-treated samples was lower than expected, ranging from 8.7 to 25.3%, while in the control samples it was 6%. Logo and Mustang turned out to be the most effective among the herbicides used in the described research. The two used application methods were found to have an effect on pollen quality.

Palyno-taxonomic approach through light and scanning electron microscopy for the identification of herbaceous Asteraceae species from Sikaram Mountain Pak-Afghan border.

Due to the diverse and rich taxa, Asteraceae needs to explore from the untouched area. In this study, the pollen study was intended to assess the taxonomic value for Asteraceous taxa growing on the Sikaram Mountain Pak-Afghan border. Both microscopic techniques (LM and SEM) play a significant role in the identification and classification of herbaceous species of Asteraceae for their taxonomic and systematic implication. Pollen was observed and measured for the 15 species of Asteraceae. For investigated taxa 15 pollen characters with size, shape, polar view, pollen type, aperture orientation, and exine sculpturing in the eurypalynous pollen. Consequently, the pollen grains are usually Tricolporate, triangular to circular in polar view, while, the shape of pollen varies from subulate, oblate, and prolate along with prolate to spheroidal whereas, sculpturing also varies from Scabrate to micro reticulate, echino-perforate, Scabrate to echinate, echinate to granulate and echinate were observed. Similarly, among the quantitative data minimum values of polar and equatorial were 15.8 ± 0.74 μm in Filago pyramidata and 17.85 ± 0.39 μm in Heteropappus altaicus was measured respectively, while; the length of the spine with the least value of 2.45 ± 0.31 μm in Hertia intermedia and highest with 7.55 ± 0.31 μm was observed in Cirsium wallichii. The Exine thickness is a minimum of 1.70 ± 0.35 μm in Launaea nudicaulis and a maximum of 5.65 ± 3.59 μm in Cirssium vulgare. In addition, the highest pollen fertility (87%) in Centaurea iberica while the highest pollen sterility (32%) was recorded in Cirsium verutum. Furthermore, clustering via UPGMA, PCA, and PCoA analysis was performed for the separation of closely related taxa. It is concluded from this research work that palynological study has a crucial role in taxonomic, pure, and applied sciences. This study can be further authenticated and improved by a Phylogenetic study based on chloroplast DNA analysis & whole genome sequencing. RESEARCH HIGHLIGHTS: Pollen ultrastructure among 15 Asteraceous taxa. Micromorphological attributes measured via LM and SEM. Exine sculpture elements patterns provide accurate identification. Taxonomic keys were developed for its systematics implications.

Pollen morphological investigation of selected species of family Asteraceae from Pakistan by using light and scanning electron microscopy.

A light and scanning electron microscopy technique was conducted to investigate the palynological features of 19 species belonging to 15 genera of the family Asteraceae. The species under investigation yielded pollen in a range of shapes, including spheroidal, prolate, and subprolate. Trizoncolporate, Tricolporate, and Tetracolporate are the three types of pollen apertures observed in examined species. Except for Gazania rigens, which has reticulate ornamentation under SEM, the exine pattern in all studied species is echinate. The majority of the species had isopolar polarity, whereas some members were apolar and heteropolar. The quantitative parameters that are polar to equatorial diameter, P/E ratio, length of colpi, width of colpi, length of the spine, width of spine, and exine thickness was measured by using light microscopy. The Coreopsis tinctoria had the lowest mean polar 19.75 μm to mean equatorial diameter 18.25 μm while the Silybum marianum had the highest polar 44.7μm to equatorial 48.2μm value. The value for colpi length/width was highest in Cirsium arvensis and lowest in C. tinctoria, measuring 9.7/13.2μm and 2.7/4.7μm, respectively. The spine length varied from 0.5μm in Sonchus arvensis to 5.5μm in Calendula officinalis. Verbesina encelioides had the highest exine thickness measurement (3.3μm), whereas S. arvensis had the lowest (0.3μm). The pollen surface of Tagetes erectus, has the highest number (65) whereas the lowest spines number (20) is found in S. arvensis. A taxonomic key based on pollen traits is provided for quick identification of the species. Significant implications for the systematics of the Asteraceae family can be drawn from the reported pollen's quantitative and qualitative data. RESEARCH HIGHLIGHTS: SEM and LM technique was used to study the palynological features of pollen grains. Quantitative and qualitative pollen features of 19 species of family Asteraceae are described. Morphological traits of pollen grains are important for the systematics of family Asteraceae.

Palynological Study of Fossil Plants from Miocene Murree Formation of Pakistan: Clues to Investigate Palaeoclimate and Palaeoenvironment

Palaeoflora in Pakistan in the Miocene is characterized by its high biodiversity. The present study investigated the pollen of fossil plants from the Murree Formation of Pakistan. Shales and mudstones were collected from the Murree section located at the foothills of the Margalla hills and analyzed by palynofacies and palynostratigraphic analyses. In this paleopalynological study of the Miocene Murree Formations of Pakistan, 31 samples were analyzed using microscopic techniques containing 48 pollen types from 12 families. The quantitative and qualitative morphological features of pollen were determined using light and scanning electron microscopy to help identify the pollen grains. Exine ornamentations and spines were the most important diagnostic features for distinguishing one pollen grain from another. The maximum exine thickness was observed in Ocimum basilicum of 4.25 μm, whereas the maximum pollen diameter was recorded for Pinus of 69.5 μm. Lamiaceae, Asteraceae, and Poaceae were the dominant families. The results showed that the preservation of floral records was not optimal. The presented results provide data on the dominant fossil plant taxa that existed in Pakistan (23.03–5.33 Ma). The evolution and phytogeographical histories of fossil plants can be unraveled using rock sediments to preserve biodiversity.

Pollen Micromorphology among Amaranthaceous Species from Desert Rangeland: Exine Stratification and their Taxonomic Significance

The aim of the study was to visualize the micromorphology of Amaranthaceous pollen using scanning electron microscopy collected from the Thal Desert. Field collection was conducted from July to September 2021. A total of 14 taxa of the family Amaranthaceae were collected which belong to nine genera. Achyranthes aspera, Aerva javanica, Aerva lanata, Amaranthus graecizans, Amaranthus retroflexus, Amaranthus viridis, Bassia indica, Chenopodium album, Chenopodium ficifolium, Chenopodium murale, Digera muricata, Haloxylon stocksii, Salsola tragus, and Suaeda fruticosa were studied in terms of pollen morphotypes. Pollen were acetolyzed and observed under optical and scanning microscopy. Qualitative and quantitative characters were measured to analyze the pollen to uncover its taxonomic significance. Qualitative characters observed were the shape of pollen in polar and equatorial views; the most frequent shape observed was spheroidal in the polar view, whereas in the equatorial view, prolate spheroidal was the dominant shape. Exine ornamentation is the key characteristic of pollen which is very helpful, and eight different types of ornamentations were observed in collected taxa: smooth sparsely granulate, scabrate‐spinulose, microspinulose perforate, microechinate scabrate to metareticulate, granulate, nanospinulate, granulate‐spinulose perforate, granulate‐perforate echinate, and microechinate perforate. Periporate‐type aperture was observed among all taxa. Mesoporia, ektexinous bodies, and tectum features also show variations among Amaranthaceous grains. In quantitative character, A. retroflexus recorded highest in polar view 26.3 μm and the lowest was of C. album 12.2 μm. Highest P/E index ratio was recorded in S. fruticosa (1.12) whereas the lowest for D. muricta (0.94). Exine thickness was highest in S. tragus 2.15 μm and lowest in A. graecizans 0.78 μm. The maximum number of pores was recorded as 32‐36 in D. muricata. Artificial taxonomic keys were constructed based on findings that reinforce the importance of the micromorphological ultrastructural diversity of pollen among Amaranthaceous taxa. It was concluded that the descriptions of pollen morphotypes presented greatly contribute to our understanding of desert species identification.