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Despite the sudden burial to which they were subjected during the eruption of 79 AD, many of the soil samples from the Vesuvian area are poor or devoid of pollen. This research assesses whether a carbonization process may be responsible for the complete or partial loss of pollen grains or, at very least, for them going unrecorded during pollen analyses. The discovery of a certain number of pollen grains in plant material from Oplontis has made it possible to investigate which heating conditions they may have been subjected to. For this purpose, in this study, modern pollen grains were exposed to different temperatures for different time intervals in order to observe their modification. The data collected indicate that exposure to high temperatures, even for a short time, can significantly impact pollen grains to the point of making them undetectable during palynological analyses. Modern pollen grains similar to those of Oplontis are observed after exposure to 300 °C for 15 min. The state of preservation of the Oplontis reticulate grains makes prolonged exposure to 300 °C or higher temperatures unlikely. The temperature indications obtained are compatible with data from other studies. The hypothesis of combustion may also explain the small dimensions of many grains found in the Vesuvian sites. [ABSTRACT FROM AUTHOR]

The pollen dispersal unit of the epidendroid species, Cephalanthera longifolia, is a soft pollinium consisting of loosely connected tetrads that are agglutinated by elastoviscin. With scanning electron microscopy, the reticulate exine is visible on the outer pollen grains of outer tetrads of a pollinium. The pollen grains are mostly arranged in planar-tetragonal tetrads or decussate tetrads and easily disintegrate into monads. Contrary to the inaperturate pollen in members of subfamily Epidendroideae known so far, C. longifolia exhibits ulcerate pollen. When pollen grains are attached in tetrads within a pollinium the apertures are obscured, as they are located on the proximal side of the pollen grains. The ulcus can only be observed when tetrads disintegrate, freeing the monads and exposing the proximal side of pollen grains for investigation by light and scanning electron microscopy. Proximal aperture configurations are rare among angiosperms and currently known only from few other species of flowering plants. This is the first report of an ulcerate proximal aperture within Orchidaceae. [ABSTRACT FROM AUTHOR]

Euphorbia L. includes 2055 species with native range of this genus being cosmopolitan. In the present study, we assessed pollen morphology of 18 species of this genus occurring mostly in northern Pakistan. Pollen morphology of Euphorbia species is poorly investigated for its taxonomic significance. Here, we examined quantitative characters, including polar diameter, equatorial diameter, P/E ratio. Exine thickness, colpi length, and width were also examined. Among the qualitative characters, pollen shape, type, exine sculpturing, and aperture features were determined. The main aim of this study is to determine and investigate the foraging behavior of the honeybees that interact with Euphorbia species. The current finding will be helpful in melissopalynological analysis for developing beekeeping practices and can be used in the authentication of honey. Pollen quantitative traits applied through a multivariate analysis and diverse sampling also improve botanical and geographical characterization of a particular region. In addition, it is concluded that some palynomorphs of Euphorbia species may contain secondary compounds and can promote signs of toxicity in honeybees. However, the beekeepers wrongly correlate the fact that milky latex from Euphorbia taxa has burning and skin irritation effects on other animals, particularly humans, with honeybee deaths, which might be due to other factors. Our observations indicate with the sense that actual forage plants may not poison their pollinators and honeybees might occasionally be dead due to unidentified factors. We have suggested that beekeepers should attempt to identify the root causes for occasional bee deaths in the area. [ABSTRACT FROM AUTHOR]

[Objective] This study explored the variations of pollen morphology among different Psi-dium guajava germplasms to provide palynological basis for cross breeding and systematic classification of P. guajava. [Method] A total of 27 P. guajava germplasms were selected from China, Thailand and Brazil. Scanning electron microscope was used to observe pollen ultrastructure and to measure polar axis length (LP),equatorial axis length (LE),pollen size (LPxLE),ratio of polar axis length to equatorial axis length (LP/LE),germination groove length (single surface) and germination groove width. All indicators were compared and the systematic cluster analysis was conducted using the intergroup connectivity met-hod. [Result] Pollen grains of 27 P. guajava germplasms existed in the form of single grains, which were radially symmetrical. The polar plane view showed nearly circular or nearly triangular shapes with obvious three-hole grooves and angular germination holes, the equatorial plane view showed oval shape, and outer wall patterns were all tumor-like. The pollen size was 11. 53 (10. 06-18. 42) μmx14. 45 (13. 45-19. 64) μm, and all were small in size grade. The ratio of polar axis length to equatorial axis length (LP/LE) was 0. 80 (0. 73-0. 94). Except for 'Caomei' with shape of nearly spherical, other 26 P. guajava germplasms were oblate spherical in shape. The length and width of germination groove were 5. 51 (3. 27-9. 95) μm and 0. 78 (0. 33-1. 26) μm. There were significant differences in above indexes among 27 P. guajava germplasms. Cluster analysis showed that the 27 germplasms could be divided into 5 groups with squared Euclidean distance of 2. 'Caomei' was gathered into one cluster separately with significantly larger LP,LE,LPxLE and LP/LE than other germplasms. [Conclusion] Germination hole, outer wall pattern and number of germination groove of P. guajava pollen had genetic conservation and pollen characteristics showed genetic diversity. Pollen characteristics reflected the variability among P. guajava germplasms to some extent. [ABSTRACT FROM AUTHOR]

AbstractAdesmia is the most species-rich genus in the informal Adesmia clade and temperate South America Leguminosae. The pollen morphology, ultrasculpture, and ultrastructure of 25 species of Adesmia were studied using light, scanning, and electron transmission microscopy to explore micromorphological data informative to the taxonomy of the genus. Additionally, a principal component analysis was performed to elucidate patterns of quantitative data variation among species concerning the most recent molecular data. We provide novel data about the genus, a comprehensive description of the pollen grains and sexine ultrasculpture, and descriptions of the exine ultrastructure. Furthermore, we suggest delimiting two pollen types based on the size of equatorial and polar axis dimensions to help in future palynotaxonomic studies and character optimisation focusing on pollen traits. [ABSTRACT FROM AUTHOR]

The current study aims to understand the role of various morphological features of pollen grains in attachment with moth proboscides. To test the hypothesis, moth samples are collected from 11 sites in three districts of Arunachal Pradesh and West Bengal, North East India. Pollen of 18 angiosperm families are isolated from the proboscides of 16 moth species in four families. We selected proboscides for the isolation of pollen because it is the most important organ of moths which interacts with flowers during moth visitation. The isolated pollen is studied for various morphological characters like pollen shape, unit, exine ornamentation, thickness, aperture numbers, and aperture types along with specialized structures i.e., viscin thread and pollenkitt, and analyzed for their attachment on the proboscides. The present study revealed the significant role of pollen shape, unit, exine characters, viscin thread, and pollenkitt in attachment with proboscides. Whereas, the aperture numbers and aperture types are found insignificant in the process of pollen attachment. Studies on the formation of viscin thread and pollenkitt may be established as an important tool to understand the specialized and generalized interactions between moths and angiosperms. The present study will open up a new horizon in pollination ecology. [ABSTRACT FROM AUTHOR]

Abstract The pollen dispersal unit of the epidendroid species, Cephalanthera longifolia, is a soft pollinium consisting of loosely connected tetrads that are agglutinated by elastoviscin. With scanning electron microscopy, the reticulate exine is visible on the outer pollen grains of outer tetrads of a pollinium. The pollen grains are mostly arranged in planar-tetragonal tetrads or decussate tetrads and easily disintegrate into monads. Contrary to the inaperturate pollen in members of subfamily Epidendroideae known so far, C. longifolia exhibits ulcerate pollen. When pollen grains are attached in tetrads within a pollinium the apertures are obscured, as they are located on the proximal side of the pollen grains. The ulcus can only be observed when tetrads disintegrate, freeing the monads and exposing the proximal side of pollen grains for investigation by light and scanning electron microscopy. Proximal aperture configurations are rare among angiosperms and currently known only from few other species of flowering plants. This is the first report of an ulcerate proximal aperture within Orchidaceae.

To provide research data for the phylogenetic evolution, classification and identification of plants in sect. Tuberculata of Camellia genus, 10 species of the section, leaf epidermal micromorphology and pollen morphology were observed by light microscope and scanning electron microscopy (SEM) and based on pollen features and leaf epidermal features to clustered separately. The results were as follows: (1) 10 species had no significant difference in pollen morphology and size, the pollen shape was subspheroidal, prolate or oblatesphere; the outline in polar view was trilete rounded or trilete regular teiangular; the outline in equatorial view was oblong or fusiform, P/E ranged from 0.85 to 1.16; the aperature type was tricolporate aperature. The exine sculpture was significantly different, the feature had coarsely warty, foveolate reticulate or rugulate with beadedmun, and had important classification value for sect. Tuberculata. (2) The cluster analysis of the measurement index showed that when the Euclidean distance was 4.5, the 10 species were divided into four groups, and some of the classification results were the same as the macroscopic morphological classification. (3) The leaf epidermal cells of 10 species were irregular or polygon, with great morphological differences among species. There were glands in the upper and lower epidermis of C. zengii, C. rhytidophylla and C. rubimuricata; cyclic type stomatal apparatuses were only distributed in the lower epidermis; anticlinal wall pattern were sinuolate, sinuous, repand and sinuate. (4) The cell size and stomatal features (size and density) of leaf epidermis micromorphology were significantly different between species. This study shows that pollen morphology and leaf epidermal micromorphology are diverse in sect. Tuberculata, which can be used as the basis for distinguishing some closely related species in sect. Tuberculata. [ABSTRACT FROM AUTHOR]

Pollen carries extensive genetic information, which may provide clues regarding the kinship of Malus, whose genetic relationships are complex. In this study, the phenotypic variation of pollen from 107 Malus taxa was investigated using combined methods of intraspecific/interspecific uniformity testing, cluster analysis, and Pearson correlation analysis. The family aggregation distributions in Malus sections, species, and cultivars were analyzed to infer their pedigree relationships. The results showed that (1) compared with pollen size and morphology, aberrant pollen rate and ornamentation were highly interspecifically differentiated, but ornamentation was also intraspecifically unstable, especially perforation densities ( c. v. ¯ > 15%). (2) The pollen alteration direction from the original to the evolutionary population of Malus was large to small, with elliptic to rectangular morphologies, large and compact to small and sparse ridges, and low to high perforation densities. However, there was no significant change in pollen size. (3) The 107 studied taxa were divided into four groups. Malus species were relatively clustered in the same section, while homologous cultivars showed evidence of family aggregation distribution characteristics (92.60% of cultivars were clustered with their parents). (4) M. baccata and M. pumilar var. neidzwetzkyana were high-frequency parents, participating in 38.7% and 20.7% of cross-breeding, respectively. Overall, this study provides a reference for identifying Malus' pedigree relationship. [ABSTRACT FROM AUTHOR]

This study employed scanning electron microscopy to investigate the pollen morphology of Taiwanese Asparagaceae species, revealing that their pollen morphology closely aligns with that of other monocotyledonous plant taxa such as Asparagales, Commelinales, and Bromeliales. Despite the overall similarity, variations in pollen morphology across different genera were noted, highlighting its potential utility in classification. Unlike the wide diversity observed in flower morphology, Asparagaceae pollen morphology appears conservative, rendering it less effective as a taxonomic marker at the species level. The study also delved into the effects of pollenkitt and harmomegathy on pollen morphology, discovering that pollenkitt partially or completely coats the pollen surface, potentially complicating the identification of exine sculpture. Furthermore, the harmomegathic effect was observed to influence aperture dynamics. Consequently, observing both hydrated and dried pollen is advisable, as it can more accurately depict the pollen's aperture morphology and offer additional insights for pollen grain analysis. [ABSTRACT FROM AUTHOR]

In this study, we report the current palynological characteristics of Iberis taxa naturally distributed in Turkey. The pollen morphology of 10 native Iberis taxa was investigated across 35 populations. In the light of our taxonomic review of Turkish Iberis taxa, a detailed palynological description is provided for the genus. The palynological characteristics of Iberis taxa were examined using scanning electron microscopy (SEM) and light microscopy (LM) to confirm their diagnostic importance at a specific and/or generic level. We evaluated different characteristics including polar axis, equatorial axis, colpus length and width, amb diameter, apocolpium, exine structure, and sculpture. Pollen characteristics were measured on 30 pollen grains from each specimen under LM. Details of the exine sculpture were also analyzed under SEM. Generally, the pollen grains of the genus Iberis are small to medium sized, radially symmetrical, isopolar, spheroidal, almost tricolpate, and rarely syncolpate or tetracolpate. The exine sculpture is reticulate, and the structure is semitectate. Two pollen types for the genus were identified based on the colpus surface feature: Iberis type I (with non-ornamented colpus surface) and Iberis type II (with ornamented colpus surface). Principal component analysis and cluster analysis were performed to reveal patterns and groupings within the related taxa concerning pollen morphology. It was found that pollen size may provide a limited but valuable metric for distinguishing Iberis species. However, due to the wide variation in some populations, it would be useful to have palynological data alongside chromosomal, molecular and macro-micromorphological data to resolve the complexity in the taxonomy of the genus. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The grasses are one of the most diverse plant families on Earth. However, their classification and evolutionary history are obscured by their pollen stenopalynous (similar) morphology. A combination of high‐resolution imaging of pollen surface ornamentation and computational analysis has previously been proposed as a promising tool to classify grass taxonomic boundaries. In this study, we test this hypothesis by studying Poaceae pollen across the phylogeny from plants collected in northern South America and also from published literature across the globe. We assessed if morphotypes that we establish using descriptive terminology are supported by computational analysis, if they vary along six (a)biotic variables and vary across the phylogeny. Based on this analysis, we constructed a reference framework for pollen surface ornamentation morphotypes. Our results showed that there is a wide variation of grass pollen surface ornamentation. We identified nine new and confirmed six known morphotypes, establishing a data set for 223 species (243 individual plant specimens) that represent 11 subfamilies. Computational analysis showed that our morphotypes are well‐supported by two quantitative features of pollen sculptural elements (size and density). The specific data set and mapping of the phylogeny confirmed that pollen morphological sculpture is unrelated to (a)biotic variables and is diverse across the phylogeny. [ABSTRACT FROM AUTHOR]

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. abyssinic a 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 .

Most Oxalis are highly ornamentally valuable, but their taxonomy is difficult, which greatly limits the landscape application of this genus. The pollen morphology and exine ornamentation of 14 species of the Oxalis were observed using scanning electron microscopy, and their pollen morphology was clustered and analyzed to explore their interspecific relationship based on the results of palynological clustering. The results were as follows: (1) The pollens of the 14 species observed were subspheroidal or oblatesphere, and in polar view they were all 3-colpate, of which 96.3% were medium-sized and 3.7% were small, with different style types showing the largest grains were produced in stamens with long filaments and the smallest ones in stamens with short filaments; most pollen grains were 3-colpate, sparsely 2-colpate and 4-colpate, O. stellata and O. pes-caprae, respectively; exine ornamentation could be divided into two categories: supra-areolate and reticulate. (2) For the first time, three species with aberrant pollen grains were observed, namely O. glabra, O. simplex and O. pes-caprae. The aberrant pollens exhibited as abnormal number and arrangement of the colpi, but normal exine structure. There were 2-zonocolpate grains in O. glabra, spiralaperturate grains in O. simplex, and 4-zonocolpate grains and spiralaperturate grains in O. pes-caprae. (3) The 14 species could be divided into two categories according to the exine ornamentation, one included O. massonorum and O. nidulans with supra-areolate pollen. The other category included 12 species with reticulate pollen. Species in the latter category could be further divided into four types: O. glabra, O. versicolor, and O. tenuifolia were more closely related; O. compressa, O. pes-caprae, O. namaquana, and O. fabaefolia were more closely related; O. bowiei, O. stellata, and O. perdicaria were more closely related; O. zeekoevleyensis and O. simplex were relatively distantly related to other Oxalis. The results of this study show that species with similar pollen morphology have certain similarity in plant morphology, and the pollen morphology characteristics can be used as the basis for the study of phylogenetic relationship and taxonomic classification, which can further provide a theoretical basis for the selection of parents in Oxalis cross-breeding.

Miyakea integrifolia Miyabe and Tatew. was considered to be an endemic genus and species to Sakhalin Island, Russia, but the monotypic genus Miyakea was later subsumed into Pulsatilla as P. integrifolia (Miyabe & Tatew.) Vorosch. This taxonomic treatment has been supported by many botanists. At present, there are two opinions on the systematic position of P. integrifolia within the genus Pulsatilla: i) a separate monotypic subgenus Miyakea situated at the last position; ii) a close relative of P. patens and P. vernalis in ser. Patentes within the species-rich subgen. Pulsatilla. Since palynological evidence might be promising morphological traits for clarifying the systematic position of Miyakea, a table summarizing the pollen morphological traits within the genus Pulsatilla was prepared using the previous appropriate palynological reports. Hitherto, the morphology of Miyakea pollen supports the second opinion i.e., a close relative of P. patens and P. vernalis. Moreover, we pointed out the issues that should be focused on in future research on the pollen morphology of Pulsatilla s.l. [ABSTRACT FROM AUTHOR]

Summary: Ruellia taboleirana (Acanthaceae) was originally described from specimens restricted to the tabuleiros litorâneos on the Northeast Brazilian coast. Here, we expand its geographic distribution to coastal areas with Amazonian influence and make important contributions on its morphology and ecology. We also present the first photos in vivo that evidence its morphological variation, along with scanning electron micrographs of pollen grains, an updated conservation status assessment, and a detailed line drawing of this species for the first time. Finally, we provide an identification key for all species of Ruellia that occur in the state of Maranhão. [ABSTRACT FROM AUTHOR]

Oil-tea belongs to the Camellia genus, an important oil crop in China. However, oil-tea is taxonomically challenging due to its morphological variation, polyploidy, and interspecific hybridization. Therefore, the present study aimed to investigate the flower organs' morphology and pollen micro-morphology of 18 oil-tea genotypes in detail and discussed their significance for oil-tea taxonomy. The quantitative parameters of flowers were measured using Vernier caliper measurements. Pollen morphology was observed and photographed using scanning electron microscopy (SEM). The results indicated that the flower size varied significantly among the tested oil-tea genotypes, with the corolla diameter ranging from 42.25 μm in C. meiocarpa 'LP' to 89.51 μm in C. oleifera 'ASX09'. The pollen grains of oil-tea are monads and medium grade in pollen size. There were two types of polar views, including triangular or subcircular, with a polar axis length (P) ranging from 27.5 μm in C. oleifera 'CY67' to 59.04 μm in C. mairei (H. Lév.) Melch. var. lapidea (Y.C. Wu) Sealy. The equatorial views exhibited oblate, spherical, or oblong shapes, with an equatorial axis length (E) of 21.32 to 41.62 μm. The pollen exine sculpture was perforate, verrucate, and reticulate. The perforation lumina diameter (D) ranged from 0.29 μm in C. magniflora Chang to 1.22 μm in C. yuhsienensis Hu, and the perforation width (W) varied from 0.77 μm in C. osmantha to 1.40 μm in C. gauchowensis 'HM349', respectively. Qualitative clustering analysis (Q-type cluster) and principal component analysis (PCA) were conducted using eleven indexes of flower and pollen morphology, and the 18 oil-tea genotypes were classified into three categories. In addition, the correlation analysis showed that there was a significant correlation between pollen size and flower morphology or pollen exine sculpture. These results offer valuable information on the classification and identification of the 18 oil-tea germplasm resources. [ABSTRACT FROM AUTHOR]

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Plants that depend on wind to disperse their pollen generate copious amounts of pollen, blow across great distances, and trigger allergies in humans, even if people live far from the source. To manage pollen allergy, monitoring the amount of pollen in the air is crucial. Airborne pollen is identified by comparing it with reference collections, using taxonomic features such as the quantity and distribution of apertures, as well as various patterns of exine ornamentation. These characteristics serve as the primary criteria for identifying atmospheric pollen. The present study contributes to aero palynological knowledge by documenting the airborne pollen spectrum in Bikaner, aiding in the identification of pollen grains with allergenic significance. These findings can inform public health strategies for managing pollen allergies and mitigating respiratory health risks associated with airborne pollen exposure. [ABSTRACT FROM AUTHOR]

Most Oxalis are highly ornamentally valuable, but their taxonomy is difficult, which greatly limits the landscape application of this genus. The pollen morphology and exine ornamentation of 14 species of the Oxalis were observed using scanning electron microscopy, and their pollen morphology was clustered and analyzed to explore their interspecific relationship based on the results of palynological clustering. The results were as follows:(1)The pollens of the 14 species observed were subspheroidal or oblatesphere, and in polar view they were all 3-colpate, of which 96.3% were medium-sized and 3.7% were small, with different style types showing the largest grains were produced in stamens with long filaments and the smallest ones in stamens with short filaments; most pollen grains were 3-colpate, sparsely 2-colpate and 4-colpate, O. stellata and O. pes-caprae, respectively; exine ornamentation could be divided into two categories: supra-areolate and reticulate.(2)For the first time, three species with aberrant pollen grains were observed, namely O. glabra, O. simplex and O. pes-caprae. The aberrant pollens exhibited as abnormal number and arrangement of the colpi, but normal exine structure. There were 2-zonocolpate grains in O. glabra, spiralaperturate grains in O. simplex, and 4-zonocolpate grains and spiralaperturate grains in O. pes-caprae. (3)The 14 species could be divided into two categories according to the exine ornamentation, one included O. massonorum and O. nidulans with supra-areolate pollen. The other category included 12 species with reticulate pollen. Species in the latter category could be further divided into four types: O. glabra, O. versicolor, and O. tenuifolia were more closely related; O. compressa, O. pes-caprae, O. namaquana, and O. fabaefolia were more closely related; O. bowiei, O. stellata, and O. perdicaria were more closely related; O. zeekoevleyensis and O. simplex were relatively distantly related to other Oxalis. The results of this study show that species with similar pollen morphology have certain similarity in plant morphology, and the pollen morphology characteristics can be used as the basis for the study of phylogenetic relationship and taxonomic classification, which can further provide a theoretical basis for the selection of parents in Oxalis cross-breeding. [ABSTRACT FROM AUTHOR]

The combined morphological features of Stratiotes (Hydrocharitaceae) pollen, observed with light and electron microscopy, make it unique among all angiosperm pollen types and easy to identify. Unfortunately, the plant is (and most likely was) insect-pollinated and produces relatively few pollen grains per flower, contributing to its apparent absence in the paleopalynological record. Here, we present fossil Stratiotes pollen from the Eocene of Germany (Europe) and Kenya (Africa), representing the first reliable pre-Pleistocene pollen records of this genus worldwide and the only fossils of this family discovered so far in Africa. The fossil Stratiotes pollen grains are described and compared to pollen from a single modern species, Stratiotes aloides L. The paleophytogeographic significance and paleoecological aspects of these findings are discussed in relation to the Hydrocharitaceae fossil records and molecular phylogeny, as well as the present-day distribution patterns of its modern genera. [ABSTRACT FROM AUTHOR]

Introduction: Borreria spinosa is a herbaceous plant considered a weed in agricultural crops, although it also has potential in apiculture. Despite its agronomic importance, its cytogenetic and palynological traits are poorly known. Objective: To do the cytogenetic characterization of B. spinosa, describe the morphology of its pollen grains, and estimate their potential viability. Methods: We collected plant material in Santiago del Estero, Argentina, in May 2017 and used classical methods (8-hydroxyquinoline and Farmer for mitosis and meiosis; viability with Müntzing; pollen morphology with nonacetolysed and acetolysed techniques, and SEM). Results: B. spinosa has a chromosome number of 2n = 56, with a karyotype of 46 m + 10 sm. Meiotic abnormalities mainly include chromosomes outside the equatorial plate, lagging chromosomes, and cytomixis. Pollen grains are small to medium-sized, suboblate to oblate-spheroidal, with a viability of 70%. This is a tetraploid species, most chromosomes are metacentric or submetacentric; and it has irregular meiotic behavior and cytomixis, with concomitant low viability in pollen grains. Conclusion: In B. spinose, pollen grains have similar characteristics to other species of the genus Borreria.

Bat pollination of Dillenia in Fiji, a genus that was presumed to be pollinated by bees, posits that other Dillenia species may be bat‐pollinated, with implications for conservation and the understanding of angiosperm evolution. Botanical descriptions of some corolla behaviours ('falling as a whole') suggest bat removal of permanently closed corollas, as in D. biflora. Considering the remoteness of species of interest, we reviewed some Dillenia floral traits to hypothesise what they may mean for bat pollination of the genus. We investigated D. biflora pollen grains apertures and reviewed Dillenia literature concerning corolla behaviour and colour, and pollen apertures and presentation, including pores and staminodes. Our samples had dramatically different ratios of tricolpate to tetracolpate pollen grains, a trait that does not exclude pollination by bees. Petal colour polymorphism occurs, with mixed colours proportionately less common in flowers with corollas that open. The proportion of species with staminodes did not differ between those presumed to be pollinated by bats and others, but anthers of the former were significantly more likely to have apical pores, and stamens all had similar length or were slightly longer in the middle, whereas stamens in two distinct groups occurred in 55% of bee‐pollinated species. Pollen heteromorphy may facilitate pollination by different taxa in tropical environments. However, anther apical pores and stamen uniformity are more likely to be associated with bat‐pollinated species than are other morphologies. Dillenia could be a useful model to examine evolutionary aspects of colour, heteranthery, staminodes and pollen heteromorphy. Only field work will verify bat pollination and the implications of bat dependence for Dillenia species. [ABSTRACT FROM AUTHOR]

The most important centre of diversity and endemism of columnar cacti in Mexico is the Tehuacán-Cuicatlán Valley (Puebla-Oaxaca states). The aims of this paper are (1) to provide a detailed description of the recent pollen morphology of 19 registered species that are found in this valley and (2) to develop a synoptic table to differentiate groups of species. This synoptic table is based on morphological features of pollen grains and the density of structural and sculptural elements observed using light and scanning electron microscopy. All analysed pollen grains were stenopalynous: isopolar monads, large, tricolpate with perforate tectate exine (sexine-nexine ratio 1:1), columellate structure with pattern of columellae distribution and spinulose sculpture. The spinules were always wider than they were tall. Although the 19 species of columnar cacti analysed in this study show highly similar types of pollen grains, we were able to characterise each of them with combined microscopy techniques. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

With the objective of evaluating the morphology of pollen in honey species from the tropical dry forest of the Quimis enclosure, five apiaries distributed in said plant formation were selected, the pollen loads obtained directly from the apiaries were collected and the bee flora was recorded according to the flowering time. The results revealed 21 honey species belonging to 13 families and 21 genera, being Convolvulus arvensis, Eriotheca ruizii, Ceiba trischistandra and Prosopis pallida the most common species and the most abundant family was Fabaceae. In relation to the pollen units, 0.95 % corresponds to the monad type and referring to symmetry, 0.67 % is characterized by being of the radiosymmetric type, while 0.48 % has tricolporate openings. Regarding the shape of the exine, 0.43% exhibited a psyllate shape, and 0.38 % showed a spheroidal shape. The months of greatest flowering coincided with June, July and August, which correspond to the dry season. The vast majority of nectariferous and polliniferous species were dominant, with the exception of Bonellia sprucei, Caesalpinia paipai and Trema micrantha, Muntingia calabura, Cojoba arborea, Sarcomphalus thyrsiflorus, Bursera graveolens, which only provide pollen and Cordia lutea and Cynophalla sclerophylla, which are nectar producers. [ABSTRACT FROM AUTHOR]

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The present study describes the results of a pollen analysis carried out using light microscopy of 8 bee pollen samples collected from apiaries established within Moara Domnească experimental station (Ilfov County) during the fall of 2021, after a summer characterized by very hot and dry weather conditions, especially during the months of June and July. The preliminary analysis indicated buckwheat pollen (Fagopyrum esculentum, Fam. Polygonaceae) as predominant in the pollen grains that were analyzed, then it indicated pollen similar to that of sunflower (Helianthus annuus), but also found in other Asteraceae species (Senecio type pollen) and in smaller amounts Crepis type pollen (can be weeds in crops or ruderal plants: Taraxacum, Leontodon, Cichorium, Tragopogon), Fabaceae-like pollen (Trifolium sp.) and Cirsium type pollen (can be Cirsium arvensis - weed in crops, but also other plants). In Romania, there are few areas cultivated with buckwheat, mostly in the northern part of Moldova. However, this is a fast-growing annual that can be grown as a late-season melliferous cover crop, whose flowers provide both pollen and nectar for honey bees and other pollinators. [ABSTRACT FROM AUTHOR]

Pollen analysis is essential for discerning the botanical and geographical origins of honey, ensuring authenticity, quality, and commercial value. The Sahara Desert in Algeria boasts unique floral diversity, with its melliferous plant species contributing to regional honey production. Nevertheless, a lack of comprehensive information on the pollen characteristics of these plants impedes precise identification of the geographical and botanical origins of Saharan honeys. Given the importance of understanding honey origin for quality assurance, this study addresses the challenge posed by the scarcity of melissopalynological data in the Sahara Desert. By offering a detailed characterization of Sahara Desert melliferous plant pollen, the research contributes valuable insights to the broader field of honey authentication and underscores its significance in the industry. Therefore, this study was conducted to characterize the pollen of melliferous plants in the Sahara Desert, which is essential for establishing a database that can aid in the determination of honey origins, protect against fraudulent activities, and support conservation efforts. This study aimed at the characterization of pollen of spontaneous melliferous plants from the Sahara Desert of Algeria to facilitate the determination of the geographical and botanical origin of honeys produced in this region. In three regions (Ghardaïa, Touggourt and Ouargla), pollen morphological features namely: polar length (PL) and equatorial diameter (ED), size, shape, apertures and exine ornamentations of 19 native plant species were studied through the sampling of ten flowers per plant and ten pollen grains per flower for each species (n = 3800 measurements). The surveyed plant species showed that medium-sized pollens (25–50 µm) were the most dominant (73.34 %), followed by slam-sized pollens (21.18 %), with the smallest size observed in Tetraena alba (PL = 18.98 ± 4.82 μm, ED = 18.95 ± 5.06 μm) and the largest size measured in Faidherbia albida (PL = 58.03 ± 4.65 µm, ED = 57.46 ± 4.70 μm). The most frequent forms of pollen in different species were prolate-spheroidal (32.68 %) and oblate-spheroidal (26.53 %). Diverse types of exine ornamentations and were detected at the pollen unit level with a dominance of reticulate (57.89 %). Tricolporate (42.11 %) and tricolpate (31.58 %) were the dominate pollen apertures. This study characterized pollen from Sahara Desert melliferous plants, which can aid honey origin determination, ensuring quality and supporting conservation, with implications in authentication, protection, and preservation of floral resources for sustained honey production.

In this study, the pollen morphology of 24 cultivars of Rose (Rosa x hybrida L.) cultivated in Egypt Pollen grain has been studied by using Light (LM) and Scanning Electron Microscopy (SEM). The pollen grains of all cultivars were monads, radially symmetrical, isopolar, and tricolporate. The size of pollen ranged from small to medium-sized. The shape varied from prolate-spheroidal, sub-prolate to prolate. Based on the exine sculpture features, four major types are recognized: striate, striate-psilate, psilate and granular verrucate. The striate type is the most dominant ornamentation with different patterns (striate with parallel striae to colpi, striate with perpendicular striae to colpi and striate with irregular pattern), while psilate and granular verrucate patterns were rarely observed in certain cultivars. The qualitative and quantitative features studied here used for cluster analysis and provide few taxonomic details which separate the cultivars. The diagnostic features of pollen grains of the studied cultivar pollen size, shape and exine sculpture.

Pollen carries extensive genetic information, which may provide clues regarding the kinship of Malus, whose genetic relationships are complex. In this study, the phenotypic variation of pollen from 107 Malus taxa was investigated using combined methods of intraspecific/interspecific uniformity testing, cluster analysis, and Pearson correlation analysis. The family aggregation distributions in Malus sections, species, and cultivars were analyzed to infer their pedigree relationships. The results showed that (1) compared with pollen size and morphology, aberrant pollen rate and ornamentation were highly interspecifically differentiated, but ornamentation was also intraspecifically unstable, especially perforation densities (c.v.¯ > 15%). (2) The pollen alteration direction from the original to the evolutionary population of Malus was large to small, with elliptic to rectangular morphologies, large and compact to small and sparse ridges, and low to high perforation densities. However, there was no significant change in pollen size. (3) The 107 studied taxa were divided into four groups. Malus species were relatively clustered in the same section, while homologous cultivars showed evidence of family aggregation distribution characteristics (92.60% of cultivars were clustered with their parents). (4) M. baccata and M. pumilar var. neidzwetzkyana were high-frequency parents, participating in 38.7% and 20.7% of cross-breeding, respectively. Overall, this study provides a reference for identifying Malus’ pedigree relationship.

Moroccan populations of Alnus glutinosa (L.) Gaerth. (Betulaceae) are found at the southern limit of the species’ range and are represented by tetraploid cytotypes with no available pollen data. The objective of this study was to assess the morphological and morphometric variability of the pollen, specifically focusing on pollen diameters and the number of apertures. To achieve this, we sampled 11 populations that are representative of the Moroccan distribution area of this species. We employed a hierarchical sampling design (11 populations, 10 trees per population, and from 30 to 300 pollen grains per tree, depending on the character measured) to examine different levels of variability: interpopulation, intrapopulation, and intraindividual. The results demonstrate that there is no discernible difference in the morphology or size of the pollen among the Moroccan tetraploid populations. However, we observed a high degree of intraspecific variability in pollen morphometric traits, but most of this variability is associated with the intraindividual level.

In this paper we present OLEAtool, a new software tool for palynological research to facilitate morphological analysis and measurements of Olea pollen. OLEAtool is a macro extension for use with ImageJ, an open-access and freely available image analysis software, and was developed as a component of the OLEA-project. This larger project examines olive tree expansion and mosaic landscape formation on the Balearic Islands. Pollen analysis of both fossil and modern grains has been proven useful for characterizing cultivars and therefore an important method for studying olive tree cultivation in the Mediterranean. However, these methods still struggle with distinguishing between wild and cultivated varieties. Traditional morphological analysis of pollen grains can be a difficult and time-consuming task. However, OLEAtool dramatically increases the speed of collecting data on pollen grains, expands the number of variables an analyst can measure, and greatly enhances the replicability of morphological analysis.

Abstract Bat pollination of Dillenia in Fiji, a genus that was presumed to be pollinated by bees, posits that other Dillenia species may be bat‐pollinated, with implications for conservation and the understanding of angiosperm evolution. Botanical descriptions of some corolla behaviours (‘falling as a whole’) suggest bat removal of permanently closed corollas, as in D. biflora. Considering the remoteness of species of interest, we reviewed some Dillenia floral traits to hypothesise what they may mean for bat pollination of the genus. We investigated D. biflora pollen grains apertures and reviewed Dillenia literature concerning corolla behaviour and colour, and pollen apertures and presentation, including pores and staminodes. Our samples had dramatically different ratios of tricolpate to tetracolpate pollen grains, a trait that does not exclude pollination by bees. Petal colour polymorphism occurs, with mixed colours proportionately less common in flowers with corollas that open. The proportion of species with staminodes did not differ between those presumed to be pollinated by bats and others, but anthers of the former were significantly more likely to have apical pores, and stamens all had similar length or were slightly longer in the middle, whereas stamens in two distinct groups occurred in 55% of bee‐pollinated species. Pollen heteromorphy may facilitate pollination by different taxa in tropical environments. However, anther apical pores and stamen uniformity are more likely to be associated with bat‐pollinated species than are other morphologies. Dillenia could be a useful model to examine evolutionary aspects of colour, heteranthery, staminodes and pollen heteromorphy. Only field work will verify bat pollination and the implications of bat dependence for Dillenia species.

The first detailed research on the pollen morphology of the Picris L. genus in Turkey was carried out in this study. Light (LM) and electron microscopy (SEM) studied five species of the genus Picris L. The pollen morphology of the genus is radial symmetrical, monad and isopolar in light microscopy examinations. Pollens are in prolate sferoidal shape, and amb is inter-hexagonal- subtriangular. Ornamentation is echinulophate. In the examinations made in electron microscope micrographs, ornamentation is echinulophate-microperforate, and tectum surface ornamentation is reticulate in paraboral lacunae in Picris cyprica Lack. and Picris strigosa Bieb. species. In the pollen of Picris altissima Delile. species and Picris kotschyi Boiss. collected from two different localities, the tectum surface ornamentation in the paraboral lacunae was observed as microperforate. The ornamentation observed on the tectum surface in abporal lacunae is psilate in all pollens. Spinule lengths in pollen are longer than spinule base widths. The ends of the spines terminate obtus-acutely. Pollen has 15 lacunae, 3 poral, 6 abporal, 6 paraboral. In the electron micrographs of the pollen, it was clearly observed that there was precipitation in the polar regions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Pollen morphology varies at inter- and intraspecific levels. Its interaction with pollinator behavior and morphology determines the probability of successful pollination. We tested whether pollen morphology promoting successful pollination differs depending on pollinator taxa in a generalist shrub, Weigela hortensis (Caprifoliaceae). We identified flower visitors carrying pollen from anthers to stigmas and compared the spine length and diameter of the pollen grains they carried. We found that pollen on the bodies of bumble bees and hunch-back flies and the scopae of small bees (including andrenid bees) contributed to seed production. Pollen grains on the bodies of bumble bees had longer spines than those on the scopae of andrenid bees or the bodies of hunch-back flies. Pollen grains on the bodies of bumble bees and the scopae of andrenid bees had larger diameters than those on hunch-back flies. Bumble bees collected pollen grains with shorter spines and larger diameters on their corbiculae while andrenid bees collected pollen grains with shorter spines and intermediate diameters on their scopae. The differences in morphology of pollen carried by pollinators reflected the tendency of bees to collect pollen with specific morphology into corbiculae/scopae. Our findings suggest that pollen morphology has diversified to facilitate successful pollination by pollinating partners. [ABSTRACT FROM AUTHOR]

Pollen morphology of 26 taxa of Clerodendrum, as well as one species of Volkameria from China, was investigated through a scanning electron microscope (SEM). Pollen grains of Clerodendrum are monads, radiosymmetric and tricolpate, with medium or large size. The equatorial view of the pollen grains is spheroidal or subprolate and the polar view is (sub) circular or rounded triangular. The colpus membrane of the investigated taxa is sunken (rarely even). Five varying pollen types are delimited on the basis of exine sculpturing: (1) spine-tectum perforatum; (2) spine-tectum imperforatum; (3) microspine- tectum perforatum; (4) microspine-tectum imperforatum; and (5) obtuser spine. The results indicate that Clerodendrum is closely related to several genera in Lamiaceae, including Aegiphila, Amasonia, Kalaharia, Tetraclea, Volkameria, Oxera, Faradaya, and Hosea, as supported by previous phylogenic studies. Additionally, the conventional infrageneric classification of Clerodendrum based on inflorescence and leaf characters is not supported by the results. However, the palynological data can be used to identify some closely related species with similar external characteristics. In conclusion, the investigation of pollen morphology not only contributes novel data from palynology for Clerodendrum but also provides a basis for future comprehensive classification of this genus. [ABSTRACT FROM AUTHOR]

Abstract Background Plant 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. Results The 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. Conclusions Although 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.

Oil-tea belongs to the Camellia genus, an important oil crop in China. However, oil-tea is taxonomically challenging due to its morphological variation, polyploidy, and interspecific hybridization. Therefore, the present study aimed to investigate the flower organs’ morphology and pollen micro-morphology of 18 oil-tea genotypes in detail and discussed their significance for oil-tea taxonomy. The quantitative parameters of flowers were measured using Vernier caliper measurements. Pollen morphology was observed and photographed using scanning electron microscopy (SEM). The results indicated that the flower size varied significantly among the tested oil-tea genotypes, with the corolla diameter ranging from 42.25 μm in C. meiocarpa ‘LP’ to 89.51 μm in C. oleifera ‘ASX09’. The pollen grains of oil-tea are monads and medium grade in pollen size. There were two types of polar views, including triangular or subcircular, with a polar axis length (P) ranging from 27.5 μm in C. oleifera ‘CY67’ to 59.04 μm in C. mairei (H. Lév.) Melch. var. lapidea (Y.C. Wu) Sealy. The equatorial views exhibited oblate, spherical, or oblong shapes, with an equatorial axis length (E) of 21.32 to 41.62 μm. The pollen exine sculpture was perforate, verrucate, and reticulate. The perforation lumina diameter (D) ranged from 0.29 μm in C. magniflora Chang to 1.22 μm in C. yuhsienensis Hu, and the perforation width (W) varied from 0.77 μm in C. osmantha to 1.40 μm in C. gauchowensis ‘HM349’, respectively. Qualitative clustering analysis (Q-type cluster) and principal component analysis (PCA) were conducted using eleven indexes of flower and pollen morphology, and the 18 oil-tea genotypes were classified into three categories. In addition, the correlation analysis showed that there was a significant correlation between pollen size and flower morphology or pollen exine sculpture. These results offer valuable information on the classification and identification of the 18 oil-tea germplasm resources.