Pollen Morphological Characters Research Articles

Morpho-palynological assessment of the genus Terminalia L. (Combretaceae) in Egypt

Eleven Terminalia species growing in streets and gardens in Cairo (Egypt) were investigated for their pollen morphology. The study's objectives were to explore the variation among Terminalia species' pollen pheno-characters and to categorize the various species within this genus according to these pollen characteristics. The results showed that there are significant variations in the pollen morphological characteristics in the genus under study, and as a result, these traits can be regarded as eurypalynous. Each of the two main categories of Terminalia species - mono-morphic and di-morphic - includes various pollen morphologies, ranging from spheroidal to prolate with hexa-aperture that may be similar or of two types. For each of the eleven species, an identification key and a clustering phenogram for the fifteen major pollen features have been created. The aperture type, aperture similarity, and exine ornamentation are some of the crucial traits for the differentiation of the species examined while the pollen shape class has a poor diagnostic character. According to the unique characteristics of the pollen morphology of the Terminalia species, three groups and two subgroups were identified.

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 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.

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.

Optimisation of classification methods to differentiate morphologically-similar pollen grains from FT-IR spectra

A growing body of research is demonstrating the potential of Fourier-Transform Infrared spectroscopy (FT-IR) to identify and differentiate morphologically similar pollen taxa. The Poaceae (grass) family is a large and complex with morphologically similar pollen grains. It is not possible to use traditional light microscopy to differentiate Poaceae species, or genus, based on pollen morphological characteristics. This research presents a study of five species from the Poaceae family found across a wide variety of different moorland vegetation communities, to test the extent to which FT-IR microspectroscopy can be used to separate and identify these species and develop statistical approaches for the analyses of these data. Moorland grasses are of particular importance to assess conservation status and baselines in fragile and scarce vegetation communities, whose vegetation composition in the past remains cryptic owing to low taxonomic resolution. Non-differentiated and second derivative spectra were combined with Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) to determine whether species had different chemical compositions and would cluster. Decision trees and random forest were used to classify each species and demonstrated 100% successful classification rate. This success demonstrates that using FT-IR microspectroscopy alongside spectral pre-processing and multivariate analysis can successfully identify and separate these moorland Poaceae species and has the clear potential to improve taxonomic resolution and classification of fossil pollen records. This will improve our understanding of how past land-use practice has shaped upland communities, provide more detailed ecologically-relevant palaeoecological information, and be utilised for the restoration and conservation of upland habitats.

Biogenic synthesis of MoO3 nanoparticles using extract of Lactuca Serriola plant of Asteraceous flora: palynomorphological studies and environmental remediation applications

The development of environmental remedies using ecofriendly and green technologies is attracting increasing research attention. Herein, the green synthesis of molybdenum oxide (MoO3) nanoparticles (NPs) using extract of selected Asteraceous flora species is reported for the first time along with the investigation of the degradation ability for organic pollutants and pollen morphological characteristics of wetland species of the family Asteraceae. An X-ray diffraction analysis confirmed the formation and crystalline structure of the MoO3 NPs. Fourier transform infrared spectra of Lactuca Serriola extract indicated the presence of capping agents, reducing agents, and phytochemicals. Scanning electron microscopy images revealed the almost spherical shape of the MoO3 NPs. A qualitative and quantitative palynological investigation of 21 species belonging to 12 genera of the Asteraceae from different wetlands of Azad Jammu and Kashmir is also reported. The MoO3 NPs degraded 99% of crystal violet dye within 30 minutes with a degradation rate of 0.022 min−1. The cost-efficient and green synthesis method for MoO3 NPs with high catalytic activity provides a new platform for the development of photocatalysts.

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.

PLANT SEGREGATION AND POLLEN CHARACTERISTICS OF HIGHLAND PAPAYA (VASCONCELLEA PUBESCENS A.DC.) BASED ON SEX TYPES

Highland papaya (Vasconcellea pubescens A.DC.) is a member of the family Caricaceae and native to Ecuador. The plant’s introduction and cultivation were successful in specific highland areas of Indonesia but with limited growing areas. V. pubescens has monoecious and dioecious characteristics and allows fruit production from female dioecious and monoecious plants. This plant is valuable, and the knowledge about its sex pattern, though still limited, is crucial for its efficiency, productivity, and development. Hence, the presented study aimed to explain the patterns of plant segregation, as well as, pollen morphology and germination based on sex in V. pubescens. The investigations began by recognizing the total population of V. pubescens in its cultivated area for grouping and mapping according to sex. Observations on the pollen characteristics, such as, morphology and germination, used light microscopy and a Scanning Electron Microscope (SEM). The results revealed that the basis for plant segregation pattern depended on sex in male and female dioecious and monoecious plants of V. pubescens (1:5:1). In both sexes, the pollen morphological characteristics showed that the unit of monads, prolate spheroidal, radial, tricolporate, isopolar, reticulate, and P/E index of male dioecious pollen was 0.70, while monoecious was 0.52. Anthers and pollen grains from the male plant were round, but those of monoecious elongate more. However, no significant differences occurred among the sexes for pollens. The pollen grains from male flowers on male dioecious plants showed faster germination than monoecious individual plants, having a difference of 25.14 days.

Pollen morphology and its taxonomic significance in Iranian Colchicum (Colchicaceae)

Pollen morphology of 15 species of Colchicum was studied using light microscopy (LM) and scanning electron microscopy (SEM). The results revealed considerable pollen character variation among the studied species, which provides helpful data for species delimitation in Colchicum. The pollen grains are monad, bilateral symmetrical, isopolar to subisopolar, prolate, perprolate, subprolate and oblate spheroidal and medium to large in size. The outline of pollen grains varies from circular to tetragonal from polar view and elliptical from equatorial view; it is dicolpate, tetrazonoporate or diporate. The results showed five types of sexine ornamentation. The current study demonstrates that the pollen morphological characters are significant in taxonomic classification of the Colchicum and provide valuable information for species identification. We performed multivariate analysis to assess the possible contribution of palynological data to the species relationships. The results of cluster and principal component analysis demonstrated a close relationship among the studied species.  

Palynology of Philippine Amorphophallus Blume ex Decne. (Araceae) and its taxonomic implications

Abstract. Fontarum-Bulawin NF, Medecilo-Guiang MMP, Calaramo MA, Alejandro GJD. 2023. Palynology of Philippine Amorphophallus Blume ex Decne. (Araceae) and its taxonomic implications. Biodiversitas 24: 4095-4109. Amorphophallus is one of the genera of Araceae with diverse pollen characters. This study aimed to investigate the pollen morphological characters of Amorphophallus in the Philippines for inferring taxonomical relationships. Light microscopy (LM) and scanning electron microscopy (SEM) were employed to investigate pollen morphology of 14 accessions of Amorphophallus. Both acetolyzed and unacetolyzed pollens were studied to compare the outward aspect of pollens and the pollen characters were subjected to cluster analysis. Results revealed that pollen grains were mostly spheroidal, prolate-spheroidal, and subspheroidal in shape. The pollen sizes vary from 3.0 to 50 µm and exhibit very small to medium sizes. The ornamentations of unacetolyzed pollens were psilate and striate, whereas ornamentations in acetolyzed pollens are varied from psilate, rugulate, rugulate hamulate, reticulate, scabrate, striateto verrucate ornamentations. All pollens were inaperturate and monad. Cluster analysis using Euclidean generated 2 major clusters, namely Cluster I consists of Amorphophallus adamsensis Magtoto, Mones, Ballada, Austria, R.M.Dizon, Alangui, Regina, Amorphophallus sp.3 (Samar), Amorphophallus yaoi A.Galloway, Hett. & Medecilo, Amorphophallus flammeus Calaramo, Batuyong, Bulawin & Alejandro, Amorphophallus urceolatus Hett. et al. (Ilocos), Amorphophallus rayongii Hett. & Medecilo, Amorphophallus sp.2 (Romblon), and Amorphophallus urceolatus Hett., A.Galloway & Medecilo (Cavite); and cluster 2 consists of Amorphophallus paeoniifolius (Dennst.) Nicolson, Amorphophallus fontarumii Bulawin, Medecilo & Alejandro, Amorphophallus rostratus Hett., Amorphophallus longispathaceus Engl.& Gehrm., and Amorphophallus sp.1 Based on this study, pollen shape, size, and ornamentation can be used as supplemental characters for the taxonomic identification of Amorphophallus in the Philippines.

Morphological diversity of pollen grains within the flowering stages of Tecoma stans (L.) Juss. ex Kunth

The study of the morphology of pollen grains is essential to understand plant evolution, adaptation, diversity and discrimination of taxa. This study aims to determine the importance of choosing the perfect stage of flower development in the study of pollen morphological characters as a taxonomical tool. In this work a woody, perennial street tree Tecoma stans was chosen as a model species belonging to family Bignoniaceae. Tecoma stans has many polymorphic forms native to North America and flourished in hot climates. This tree is commonly planted in both Cairo and Alexandria streets. Samples of flower buds in nine different stages were gathered from five to six different trees from March to June 2023. Non-acetolysed pollen grains were investigated using both light and Scanning electron microscopes. The results showed that pollen density, size, shape beside colpi length as well as their state varied between the different developmental flowering stages and cannot be relied on taxonomical decisions, while exine ornamentation slightly differed between the pollen grains from stage two to nine, but it was faint in immature flower bud (stage one). This study confirms that we must be precise in choosing the correct flower stage in pollen morphological studies to obtain significant morphological description. The results obtained revealed that the aperture type is more stable than pollen shape and size.

Common allergenic pollen types during winter in the atmosphere of Deccan Park of Tolichowki area, Hyderabad, T.S.– A pollen morphological study

The present paper focused on the pollen morphological characters of some common allergenic plants collected from the Deccan Park, situated next to Qutub Shahi tombs in the Golconda Tolichowki area of Greater Hyderabad, Telangana state during winter from November 2019 to February, 2020. The study highlighted ten genera viz., Ailanthus excelsa, Alternanthera sessilis, Casuarina equisetifolia, Celosia argentia, Holoptelea integrifolia, Peltophorum pterocarpum, Prosopis juliflora, Ricinus communis, Tinospora cordifolia and Xanthium strumarium.  These plant taxa belong to 9 families. The common allergenic pollen grains of these plants have diversity of morphological characters viz., symmetry shape, polarity, apertural pattern and sculpture.

Pollen morphology of Artemisia L. (Asteraceae) in Turkey and its systematic value

The objective of the current investigation is to use scanning electron and light microscopy to obtain pollen morphological information for all Artemisia taxa growing in Turkey. In addition, statistical analyses were performed and a dichotomous key was prepared for the identification of taxa using pollen characters. Pollen grains of Artemisia are radially symmetrical, isopolar, oblate-spheroidal, and prolate-spheroidal, with the polar axis ranging from 15.23–27.20 µm. The equatorial diameter ranges from 16.48–27.47 µm. Artemisia taxa typically have tricolporate, tricolpate pollen. However, pantocolporate, pantocolpate, and syncolporate pollen grains are rarely present in A. austriaca and A. armeniaca. Our study showed that, although other Artemisia taxa have an ornamentation that is microechinate-granulate, A. incana, A. taurica var. vanensis, and A. spicigera differ by their microechinate ornamentation. Furthermore, we found that A. chamaemelifolia contains the highest number of microechinae per 25 µm2, whereas A. fragrans had the fewest. Additionally, the average number of granules differs between taxa. The number of granules per 25 µm2 is the highest in A. scoparia and the lowest in A. santonicum subsp. santonicum. Furthermore, the UPGMA (unweighted pair group method with arithmetic mean) dendrogram indicated that there are three different groups of taxa based on pollen morphological characteristics from 26 taxa. The average number of granules per 25 µm2, as determined by the principal component analysis, plays a significant role in this classification scheme.

The pattern of natural variability of palynomorphological features with the example of some <i>Nierembergia</i> and <i>Bouchetia</i> species (Solanaceae) and natural system of bio-variety

On the example of pollen morphological features of 8 species of Nierembergia and 2 species of Bouchetia (family Solanaceae), the properties of individual variability are described. Most of the studied characters (structure of apertures, ultrastructure of the sporoderm, surface sculpture, dimensions) do not have significant differences at the individual and intraspecific levels; taxonomically significant variability of morphological features of pollen is manifested at the level of the genus and suprageneric groups. The genera differ significantly in the sculpture of the pollen grain surface – striate in Nierembergia and tuberculate in Bouchetia. Pollen contained in one bud, anther or tetrad (fully completed gametophytic generation, where there is no death – all descendants of one ancestor without exception), is considered as an extreme model (maximum completeness with minimum complexity) to study the properties of natural morphological variability and the causes of its occurrence. It was found that pollen characters (sculpture, number and location of apertures) have the same pattern of variability (continuous and transitively ordered series), which embodied at different taxonomic levels in different characters. The natural variability of pollen morphological features is ordered not into a genealogical clade, but into a cline – continuous, geometrically ordered and transitive series (taxon-nonspecific and rank-independent). In this system of parallelisms, homological series are inseparable from non-homological ones, and typical forms, from deviations. The origin of typical and deviant forms cannot be explained separately (typical – genealogically, and deviant – as parallelism, convergence, chance or regularity). The individual variability of pollen forms is geometrically ordered and is not the result of random disturbances, failures of the hereditary program, or pathology. The typical form turns out to be a harmonious part of a geometrically ordered series of pure forms, free from functional and historical connotations. The similarity of pollen forms in these series is determined by their geometry and does not depend on affinity, homology, functionality (improvement, exercise, adaptation). The natural system of pollen forms is formed not by the structure of supposed affinity of supposed taxa (universalia, general concepts, the result of speculation that requires confirmation and admits refutation), but the structure of the observed parallelisms of the variability of individual living bodies. Evolutionary novelty (the current state, the observed variability) arises initially ordered in a pre-established form.

Pollen morphology of twenty three species of Allium L. (Amaryllidaceae) species from Turkey

The pollen morphology of 23 Allium L. species, grown in Turkey, belonging to the sections; Rhizirideum, Schoenoprasum, Cepa, Molium, Brevispatha, Scorodon, Acanthoprason and Melanocrommyum, were investigated by LM (light microscopy), TEM (transmission electron microscope), and SEM (scanning electron microscopy). This paper presents detailed pollen morphological features are given for these taxa. Common characteristics of pollen of Allium species investigated are ellipsoidal and heteropolar, bilateral symmetry; pollen grains are shed as monads. They are monosulcate (extended sulcate types) and monosulcate-operculate. The sculpturing of the exine, pollen membrane ornamentation, lumina shape, and sulcus membrane with a fragmented operculum are found to be characteristic features for separating species. Based on these properties three main pollen types were determined with three different exine sculpturing. The characteristic structures of pollen ornamentation, observed in SEM micrographs, are striate­perforate, striate­regulate-perforate and regulate-perforate. Sulcus membrane ornamentations are psilate, psilate-perforate, rugulate and regulate-perforate. The exine is semitectate and the tectum perforate. Columellae were found to be simplicolumellate. Bangladesh J. Plant Taxon. 30(1): 1-19, 2023 (June)  

A taxonomic study on pollen morphology, karyotype features, floral and fruit pigment components of 13 taxa of Lonicera L.

Due to extensive introduction and breeding, the taxonomic relationships of Lonicera L. are unclear. Alternative scientific methods are needed to explore the classification of these new Lonicera. In this paper, the pollen morphology characteristics, karyotype features, and floral and fruit pigment components of 13 taxa of Lonicera were analyzed by means of scanning electron microscopy, karyotype analysis, High Performance Liquid Chromatography Mass Spectrometry (HPLC-MS) and Gas Chromatography-Mass Spectrometry (GC-MS). The 13 representatives of Lonicera were divided into groups of four, three, three and three taxa through the analysis of pollen morphology characteristics, karyotype features, floral composition and fruit pigment composition, respectively. Lonicera ruprechtiana and Lonicera tatarica always clustered together. Five hybrids, including Lonicera korolkow × Lonicera maackii and Lonicera korolkow × Lonicera tatarica No. 8 can generally be clustered with their parents. These results indicate that the analysis of pollen morphology characteristics, karyotype features, and floral and fruit pigment composition has value and significance for the study of systematic classification and relationships, and the conclusions of this study partially support morphological taxonomy.

Evaluation of grass pollen quality control for allergy test kit production using pollen morphological characters

Grass pollen is one of the leading causes of allergies in throughout the world. The symptom level depends on the personal immunity. Pollen allergy test kits are suitable for detecting allergic symptoms, which they are produced from pure pollen of specific species. The production of pollen allergy testing kits requires accurate botanical standards and identification for the process of quality control of raw materials basing on Thai Food and drug ministration (Thai FDA). To produce allergy test kit, we focused on the pollen of these 6 common grass species and also use pollen morphological characters for detection and identification. Therefore, this study focused on the method for qualification control and standardization for prototype product of grass pollen allergy testing kit. Six common grass species as Megathyrsus maximus (Jacq.) B.K.Simon & S.W.L. Jacobs, Oryza sativa L., Sorghum bicolor (L.) Moench, Urochloa eminii (Mez) Davidse, Urochloa mutica (Forssk.) T.Q.Nguyen and Zea mays L.). The criteria were: 1) common in Thailand and Southeast Asia; 2) high density in the atmosphere; and 3) severity of the allergic reaction. The modified acetolysis were applied for samples preparation. The pollen morphological (polar and equatorial axes, exine, porus, annulus and ornamentation) were observed and measurement under light and scanning electron microscope. The character matrix was analyzed based on a regression tree and Tukey’s HSD test to assess support for the different pollen morphological characters. The distinguished character is ornamentation. The results were successfully described the pollen species and showed that the pollen morphologies were useful for contaminated detection. In addition, this method was suitable applied for qualification control of the raw materials for grass pollen allergy testing kits production.

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.

The morphological diversity of pollen in the genus Gossypium

BackgroundPlant pollen has diverse morphological characteristics that can be consistently passed down from generation to generation. Information on pollen morphology is thus immensely important for plant classification and identification. In the genus Gossypium, however, in-depth research on pollen morphology is lacking, with only few reports on limited cotton species. To evaluate the diversity of pollen in Gossypium, we therefore conducted a comprehensive analysis of the pollen morphology of 33 cotton species and varieties using scanning electron microscopy.ResultsThe 33 analyzed cotton samples exhibited common pollen morphological features, including spherical shapes, radial symmetry, echination, panporation, and operculation, while the pollen size, spine shape, spine density and length showed distinctive features. Pollen size varied significantly among species, with diameters ranging from 62.43 μm in G. harknessii to 103.41 μm in G. barbadense. The exine had an echinate sculptural texture, and spines were mostly conical or sharply conical but occasionally rod-like. Spine density varied from 173 in G. incanum to 54 in G. gossypioides, while spine length ranged from 3.53 μm in G. herbaceum to 9.47 μm in G. barbadense. In addition, the 33 cotton species and varieties were grouped at a genetic distance of 3.83 into three clusters. Cluster I comprised five allotetraploid AD-genome cotton species, four D-genome species, and one K-genome species. Cluster II included 13 diploid species from A, B, D, E, and G genomes, whereas Cluster III only consisted one E-genome species G. incanum.ConclusionsAlthough pollen characteristics alone are not enough to resolve taxonomic and systematic relationships within the genus Gossypium, our results add to knowledge on palynomorphology and contribute to phenological information on these taxa. Our findings should aid future systematic and phylogenetic studies of the Gossypium genus.

Heterostyly and pollen dimorphism of <i>Menyanthes trifoliata</i>

<i>Menyanthes trifoliata</i> L., a heterostyly plant, is an endangered species in Korea. Floral morphology has been published for <i>M. trifoliata</i>, but few works have concentrated on pollen dimorphism differences accompanied by floral dimorphism. Here, we conducted a comparative morphological study of two morphs to investigate a dimorphism system with Korean populations. Pollen morphological characteristics were observed with a light microscope and a scanning electron microscope. For the pin type, pollen size is 36.01 ± 2.01 µm, whereas for the thrum type it is 41.28 ± 2.58 µm in terms of the equatorial diameter. The two morphs have a small apocolpium field at 5.62 ± 0.30 for the pin type and 6.24 ± 0.70 for the thrum type. The configuration of the aperture was tricolpate with a striate ridge in the two morphs. However, they have different pollen shapes and sizes, stigma shapes, and apocolpium sizes. <i>M. trifoliata</i> only has different pollen sizes and shapes between European populations and Korean populations. Nevertheless, Korean populations also show pollen dimorphism correlated with their floral dimorphism.