Pollen Samples Research Articles

Forensic potential of pollen grains: A case study from continental Croatia (town of Donja Stubica)

Background and Purpose: Pollen grains can come as “ invisible” traces during forensic palynological expertise. As forensic palynology is not carried out in Croatia at all, the main aims of our work were to establish an initial palynological collection for a limited area in Croatia and determine its forensic potential. Materials and Methods: For our case study, we chose a typical town from continental Croatia, Donja Stubica, in which there had been no previous floristic studies. The field survey was conducted during 2005, 2007, and 2021. Floristic and palynological analysis was carried out with an emphasis on the forensic potential of pollen grains. Results: A total of 141 representative plant taxa with pollen samples were collected. The taxonomic analysis showed that the area for the case study was chosen well. Palynological analysis showed that the highest number of taxa had pollen grains that were spheroidal in shape (60%), medium sized (70%), and colporate (41%). The pollen of the majority of taxa had excellent or very important forensic potential, due to their dispersal by insects (60%), a combination of two dispersal methods (23%), and autogamy (1%). In addition, due to the limited distribution of certain rare plants (e.g., Iris sibirica subsp. sibirica in Croatia), their pollen has an even greater forensic potential than the similar pollen of related, more widespread taxa. Conclusion: The generated palynological collection, due to the great forensic potential, could be used in the future as a comparative, and at least partly as a reference forensic collection, applicable in specific cases of legal pollen expertise in Croatia.

Characterization of Argentine commercial bee pollen intended for human consumption

Bee pollen is consumed as a dietary supplement. Its quality parameters are regulated by the Argentine Food Code (AFCode). The present study characterized 10 commercial dehydrated samples from five Argentine provinces to provide information on hygienic quality and health safety. We assessed their microbiological quality, including potential mycotoxins. We also determined their botanical origin and moisture. Results showed that seven out of ten samples presented lower counts of culturable heterotrophic mesophilic bacteria than those allowed by the AFCode. In contrast, all samples showed higher filamentous fungi and yeast counts than the level approved by the AFCode. No fumonisin or deoxynivalenol was detected; we observed only aflatoxin B2 in one sample and ochratoxin A in two. The results of the botanical origin of samples showed that all samples had a predominant pollen type, except one. The microbiological quality of all samples agreed with that required by the AFCode, except filamentous fungi and yeasts. In addition, we found variations among samples from the same province. Therefore, if pollen is intended for human consumption, appropriate hygiene standards must be applied to all bee pollen production operations. Highlights: The microbiological quality of bee pollen samples, regardless of the province or botanical origin, agreed with the requirements of the AFCode, except for filamentous fungus and yeast. All samples showed filamentous fungus and yeast counts higher than the permitted level in the AFCode. Mycotoxin levels found in bee pollen were far from the limits allowed in humans (10 µg.kg-1) by regulations for other foods. All samples analyzed were pollen mixes verified by identifying numerous botanical species. The characterization of Argentinian commercial bee pollen showed that it was suitable for human consumption.

Pollen variability in Quercus L. species and relative systematic implications

This study aims to address one of the challenges related to the complexity of the Quercus L. genus, that is the identification of structural elements favouring the systematic identification of the oak pollen. Thus, in this contribution, we explored the variation of morphometric and chemical parameters in pollen samples collected from 47 different Quercus species and hybrids. Several qualitative (e.g., outline in polar view, class, aperture structures) and quantitative (e.g., diameter, exine and sporoderm thickness, autofluorescence, content in proteins and plant metabolites) features were evaluated by optic microscopy and spectrophotometric assays. Statistical analyses were also carried out to assess significant correlations and clustering effects among the studied taxa, based on phenotypical and biochemical data, to identify the parameters which could be useful for taxonomic discrimination at inter- and intra-specific level. Only few morphological traits showed the potentiality to be diagnostic, such as pollen diameter and outline in polar view. The intensity of pollen autofluorescence varied among the samples but it did not seem to correlate with protein, carotenoid, phenolic and flavonoid content. However, differences in protein and carotenoid levels were detected, suggesting them as possible taxonomic discriminants for oak pollen. Thus, our work represents a step forward in understanding morphology and biochemistry of oak pollen, constitutes an experimental set-up applicable in future systematic studies on other genera, and opens new perspectives for further molecular investigations on Quercus species.

Method optimisation for large scope pesticide multiresidue analysis in bee pollen: A pilot monitoring study

Pesticide contamination in emerging foods and supplements is currently a topic of great interest. This study focused on the evaluation of pesticide residues in commercial bee pollen samples to evaluate the risk associated with their consumption. To this end, an automated clean-up method for the pesticide extracts of bee pollen was developed. An LC-MS/MS and a GC-MS/MS method were validated for the analysis of 353 pesticides in 80 bee pollen samples purchased from different countries. The results showed the presence of 77 different pesticide residues in bee pollen, including plant protection chemicals and veterinary treatments. 85 % of the samples were contaminated with pesticides and no relevant differences were found between conventional and organic samples. Pesticide concentrations exceeding the imposed MRL were found in 40 % of the samples, but the risk assessment showed that consumers are not exposed to an unacceptable risk when consuming the evaluated bee pollen.

Pollen available during anthesis of Hylocereus undatus flowers

Pitahaya (Hylocereus spp) is a fruit that, due to the characteristics of its demand, both for fresh fruit and for industrial consumption, has detonated its development in various countries. However, it presents various self-incompatibility mechanisms that impact productivity. Therefore, the viability of pollen was analyzed during the anthesis (or flowering period)of two white-fleshed H. undatus cultivars, taking pollen samples for 13 hours, from the beginning of the anthesis in the afternoon, until it ends the following day. The method used was staining with tetrazolium salt (2,3,5-triphenyltetrazolium chloride) or TZ. The results showed that there is no viable pollen at the beginning of the anthesis. At 09:00 pm the viability began to grow slowly and after 12:00 am it doubled and the viability accelerated, marking the highest from 02:00 to 04:00 am. It was possible to observe the consistency of the pollen that begins with a phase I with humid pollen without viability, up to another with lower humidity with low viability (phase II). Phase III observed very granular mealy pollen, easy to handle precisely when the staining readings marked the viability of 93 % to 95 %. Subsequently, the viability decreases until it disappears when the floral structure begins to dehydrate.

Taxonomic study of pollen grains for five species of Fabaceae Family

The objective of the study was to provide valuable palynological characteristics for the identification of Fabaceae taxa, which could potentially serve as distinguishing features for closely related species differentiation. Pollen samples were collected from fully developed flowers of 25 samples, encompassing five species within the Fabaceae Family Colutea cilicica Boiss. & Balansa, Glycyrrhiza glabra L., Spartium junceum L., Robinia pseudoacacia L., and Anagyris foetida L. The investigation involved the utilization of both light microscopy and electron scanning microscopy. Consequently, the observed pollen grains exhibited monad symmetry and were of medium to small dimensions. These grains displayed diverse ornamentation patterns including perforations, fossulate, reticulations, regular structures, and granulations. Moreover, a wide array of outline shapes was noted for pollen grains in both equatorial and polar views. Detailed examinations were performed using both light microscopy (LM) and electron scanning microscopy (SEM) techniques, revealing distinct differentiating characteristics among the examined taxa.

Quantitative reconstruction of precipitation changes in the Mongolian Altai Mountains since 13.7 ka

Holocene climate changes in the Altai Mountains and the surrounding areas are well documented, but the timing of the Holocene precipitation maximum remains controversial. We obtained 17 accelerator mass spectrometry (AMS) 14C dates and 310 fossil pollen assemblages from sediments in Tolbo Lake, which we used to reconstruct the history of vegetation and climate change in the Mongolian Altai Mountains over the past 13,750 years. The results suggest that mean annual precipitation (Pann) was the most significant control on the fossil pollen record at the study site. Based on the fossil pollen record from Tolbo Lake and 469 surface pollen samples within the radius of 1300 km, the reconstructed Pann was lowest during 13.7–11.3 ka (1 ka = 1,000 cal yr BP); relatively low but increasing Pann occurred in the early Holocene (11.3–9.4 ka); and maximum Pann occurred during the middle to late Holocene (after 6.8 ka), possibly because of the high temperatures. A significant climatic and ecological transition occurred in the Altai Mountains at ∼7 ka: steppe and desert steppe vegetation with generally low Pann was present before ∼7 ka, while subsequently there was the expansion of forest vegetation and a marked increase in Pann, possibly in response to the minimum in Northern Hemisphere ice sheets and the increased radiative forcing caused by rising atmospheric greenhouse gases.

The vertical distribution of modern pollen in the southeastern edge of the Tibetan Plateau, China

The tropical mountainous area of the southeastern Tibetan Plateau (TP) is a hotspot of ecological environment research because of its rich biodiversity. However, limited knowledge regarding modern pollen rain within this area has impeded further investigation of eco-environmental evolution using the pollen record. We collected 62 modern pollen samples from lowland tropics to the subalpine region (740–3550 m a.s.l.) in Medog County, located in the southeastern TP, and performed pollen analysis. Cluster analysis, redundancy analysis, variance partitioning analysis, and boosted regression trees were employed to investigate the relationship between pollen and vegetation/climate. Additionally, Hill numbers (N0, N1, N2) and specificity–occupancy plots were utilized to explore plant diversity. The results indicate that modern pollen rain in Medog reflects well the current characteristics of the vegetation, encompassing both primary and secondary features. Pollen of Cyclobalanopsis, Tsuga and Abies, which are dominant components of the primary vegetation above 2100 m a.s.l., can serve as indicator species for paleovegetation reconstructions. Mean annual precipitation is the most important climatic determinant affecting pollen distribution. Pollen indices reveal that the plant diversity in this study area has a bimodal pattern of ‘relatively high–low–highest–low’ with increasing altitude. The plant diversity above 2100 m a.s.l. is mainly decided by primary vegetation, whereas below 2100 m a.s.l. it can be explained by the intermediate disturbance hypothesis. Furthermore, it is advisable to exercise caution when dealing with arboreal pollen evenness in open mountainous environments due to the increased potential pollen source area caused by valley wind.

The Influence of Enzymatic Hydrolysis on Bee Pollen Antioxidant and Antibacterial Activities.

Bee pollen is one of the most valuable apitherapeutic products with high nutritional value. To obtain a higher diversity of compounds, higher bioactivity, and improve the release of nutrients from bee pollen, additional processing of the raw material may be applied: fermentation using microorganisms or hydrolysis using selective enzymes. This research aimed to determine the impact of enzymatic hydrolysis on the antioxidant and antibacterial activities of bee pollen. Bee pollen samples from Sweden, Spain, Netherlands, Italy, Poland, Denmark, Slovakia, Malta, and Lithuania were hydrolyzed using pure enzymes, including lipase, cellulase, protease, and amyloglucosidase, as well as enzyme mixtures such as Viscozyme® L and Clara-diastase. Total phenolic content, total flavonoid content, and antioxidant activity were analyzed spectrophotometrically. Antibacterial activity against Staphylococcus aureus, Listeria monocytogenes, Staphylococcus enteritidis, and Salmonella typhimurium was evaluated using the agar well diffusion assay. Obtained results revealed a positive effect of enzymatic hydrolysis on biologically active compound content and activity: total phenolic content increased by 1.1 to 2.5 times, total flavonoid content by 1.1 to 3.0 times, radical scavenging activity by 1.1-3.5 times, and antibacterial activity by 1.1 to 3.3 times. K-means clustering analysis grouped samples into 5-9 clusters and was dependent on the measured characteristic used as an input-total phenolic compounds content, total flavonoid content, antioxidant activity, and antibacterial activity against four different bacteria. Chemometrics showed, that the enzyme used for the hydrolysis had a higher impact on clustering results than the geographical origin of the samples.

Determination of highly polar anionic pesticides in beehive products by hydrophilic interaction liquid chromatography coupled to mass spectrometry.

The analysis of highly polar pesticides is challenging due to their unique physicochemical properties, requiring specialized chromatographic techniques for their accurate and sensitive detection. Furthermore, the high level of co-extracted polar matrix components that can co-elute with the analytes can interfere with the analysis. Consequently, there is lack of pesticide monitoring data, as the European Food Safety Authority has pointed out. This article explores the overcoming of such difficulties in the analysis of these compounds. Analytical methodologies for the extraction, clean-up, and direct determination of 11 highly polar anionic pesticides, including glyphosate, glufosinate, ethephon, fosetyl-aluminium, and their related metabolites in complex food matrices such as honey and pollen by hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry were successfully developed and validated. Solid-phase extraction and micro-solid-phase extraction employing strong anion exchange (SAX) cartridges were implemented for clean-up. The automation and miniaturization of SAX clean-up for these compounds were achieved for the first time. For method validation, SANTE/11312/2021 guideline was followed. Recoveries were between 70 and 120%, with RSDs below 20%. Limits of quantitation ranged from 0.005 to 0.020 mg kg-1. Linearity was evaluated from 0.002 to 0.200 mg kg-1. Matrix effects were assessed, showing medium to low signal suppression for most compounds. AMPA and glufosinate presented the highest signal suppression, but it was reduced after SAX clean-up. Analysis of real honey and pollen samples revealed the occurrence of the studied compounds in beehive products and showed the applicability of the validated methodologies for routine control of these complex samples.

‘The man who vacuum cleaned the Atlantic’ − the aerosol collector and Gunnar Erdtman’s attempts to measure pollen rain

In 1937, the Swedish palynologist Gunnar Erdtman (1897–1973) mounted two adapted vacuum cleaners atop an ocean-going liner and set out to obtain air samples as he crossed the Atlantic Ocean. The devices were able to capture samples of airborne pollen which were related to air volume and distance from land. The results of this investigation are still cited in the scientific literature, but a study of publications demonstrates that the ocean study had land-based antecedents. Furthermore, archival investigation reveals the background to such studies, including the technical plans for Erdtman’s ‘aerosol collector’, records of raw data from the voyage, draft portions of the key publication, photographs and the precise location of the land-based equipment. A storage loft in the Swedish Museum of Natural History in Stockholm has been found to house a surviving aerosol collector.

Surface soil pollen and climate in northern Xinjiang, China: Implications for paleoclimate reconstruction

Quantitative paleoclimate reconstruction based on surface soil pollen and climate records on a regional scale is widely applied as a standard approach to investigating past climate changes. This study aimed to explore the quantitative relationships between the distribution of pollen taxa in 438 pollen samples from surface soils at altitudes ranging from 190 m to 3235 m and 19 environmental parameters in northern Xinjiang, China, using ordination and correlation analyses. The results showed that mean annual precipitation (MAP), precipitation in July, mean annual temperature (MAT), mean temperature in July and mean annual wind speed were the main environmental factors influencing the surface pollen distribution. Pinus pollen dispersal and transportation were primarily affected by spring wind, suggesting that exotic pollen played an essential role in surface pollen distribution. Picea pollen, with a percentage and concentration of over 30% and 30000 grains/g, was distributed at sites with MAT and MAP of −5.1–1.2 °C and 212–459 mm, respectively. Artemisia and Chenopodiaceae, with percentages and concentrations of over 50% and 50,000 grains/g and 50% and 10,000 grains/g, respectively, were mainly distributed at sites with MAT and MAP of −1.9–9.1 °C and 145–416 mm, and −3.2–8.9 °C and 129–449 mm, respectively, providing an accurate reference for paleoclimates reconstruction. This study presents information regarding the relationship between surface soil pollen and climate records, which may contribute to the reconstruction of historical climates, promote ecological development in Xinjiang, China, and assist in predicting future climate trends.

Probiotic potential of Bacillus Isolates from Polish Bee Pollen and Bee Bread.

The main goal of this study was the evaluation of the probiotic potential of 10 Bacillus spp. strains isolated from 5 bee bread and 3 bee pollen samples. The antagonistic interaction with Staphylococcus aureus and Escherichia coli was a primary criterion for the preliminary selection of the isolates. Three out of ten strains-PY2.3 (isolated from pollen), BP20.15 and BB10.1 (both isolated from bee bread)-were found to be possible probiotic strains. All these strains are safe for humans (exhibiting [Formula: see text]-hemolytic activity) and meet all essential requirements for probiotics in terms of viability in the presence of bile salts and acid conditions, hydrophobicity, auto-aggregation, and co-aggregation with the cells of important human pathogenic bacteria. They also assimilate more than 30% of cholesterol after 24h of incubation. These three isolates are resistant to penicillin but sensitive (or exhibit moderate resistance) to the other nine antibiotics tested herein. On the basis of whole-genome sequencing, BP20.15 and BB10.1 were classified as B. subtilis and PY2.3 as B. velezensis. Moreover, genomic analyses revealed that all these isolates are potential producers of different antimicrobial compounds, including bacteriocins and secondary metabolites. The outcomes of this study have proven that some of the Bacillus strains isolated from bee pollen or bee bread are potential probiotics.

Diversity of Plants Foraged by Apis cerana Fabricius Around Qinling Mountains (Central China) Based on Honey Pollen Samples

Diversity of Plants Foraged by Apis cerana Fabricius Around Qinling Mountains (Central China) Based on Honey Pollen Samples

Diversity matters: Diet of Apis cerana in southeast India includes one consistently occurring and several seasonally available floral sources

Little is known about the agroecological implications of the Asian honey bee Apis cerana Fabricius in its vast native range including southeast India. To identify the foraging preferences of this generalist species, we collected 388 corbicular pollen samples over three years at Merveille, an eco-restoration site in Puducherry region, southeast India. Pollen was collected twice or thrice weekly from March 2018 to December 2021 in three locations within the site. We used canonical correspondence analysis to evaluate how average daily temperature, humidity and other meteorological changes over the years would influence A. cerana’s diet. We show that (1) A. cerana has a large dietary niche (87 pollen taxa), but essentially feeds on Cocos nucifera (all year long) and on Borassus flabellifer, Turnera, Acacia, Mollugo/Trianthema, Leucaena/Prosopis, Portulaca, Poaceae, Syzygium-t, Dodonaea viscosa and Boerhavia seasonally; these were most frequently and abundantly foraged at all locations. (2) In all locations, bees preferentially feed on arboreal plants (44 taxa). (3) Bees' pollen diet varies in composition according to seasons. It is also least diverse in the hottest and driest months (March-May) with 2–4 taxa against 7–13 taxa in other months. (4) In 2021, which was more humid and slightly cooler than 2018 and 2019, bee diet included more pollen of Cyperaceae, Dodonaea viscosa, Liliaceae and fallow land weeds such as Boerhavia and Mimosa pudica. In conclusion, corbicular pollen loads of Apis cerana provide a long and continuous record of the bee’s diet and its changes through time and space. The diet changed according to subtle changes in humidity and temperature as also drastic changes in rainfall at the study site, likely reflecting changes in the floral resource availability and the bees’ preference. The sustained presence of this bee species within its native ranges can be a bellwether of pollinator friendly habitats.

Honeybees’ foraging choices for nectar and pollen revealed by DNA metabarcoding

Honeybees are the most widespread managed pollinators of our food crops, and a crucial part of their well-being is a suitable diet. Yet, we do not know how they choose flowers to collect nectar or pollen from. Here we studied forty-three honeybee colonies in six apiaries over a summer, identifying the floral origins of honey and hive-stored pollen samples by DNA-metabarcoding. We recorded the available flowering plants and analyzed the specialized metabolites in honey. Overall, we find that honeybees use mostly the same plants for both nectar and pollen, yet per colony less than half of the plant genera are used for both nectar and pollen at a time. Across samples, on average fewer plant genera were used for pollen, but the composition was more variable among samples, suggesting higher selectivity for pollen sources. Of the available flowering plants, honeybees used only a fraction for either nectar or pollen foraging. The time of summer guided the plant choices the most, and the location impacted both the plants selected and the specialized metabolite composition in honey. Thus, honeybees are selective for both nectar and pollen, implicating a need of a wide variety of floral resources to choose an optimal diet from.

To rewire or not to rewire: To what extent rewiring to surviving partners can avoid extinction?

Research Highlight: Leimberger, K.G., Hadley, A.S., & Betts, M.G. (2023). Plant-hummingbird pollination networks exhibit minimal rewiring after experimental removal of a locally abundant plant species. Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.13935. In this paper, Leimberger, Hadley and Betts (2023) explore the effects of removing a locally abundant plant species on plant-hummingbird pollination networks. They experimentally prevented access of hummingbirds to flowers of Heliconia tortuosa and assessed subsequent changes in the interactions between plants and hummingbirds. Their main hypothesis postulated that the loss of a highly connected species would lead to interaction rewiring and niche expansions by hummingbirds, decreasing individual, species and network specialization. However, they found that the overall structure of the plant-hummingbird networks remains mostly unaltered, with limited rewiring and minimal changes in specialization. The main contributions of this study can be summarized as (i) it adds to a limited number of manipulative studies on the capacity of species to rewire their interactions following the loss of partners, and importantly, it is the first study from the tropics and with vertebrate pollinators, for which experimental studies at appropriate scales is intrinsically more challenging; and (ii) innovates by evaluating change in specialization for the individual level, carried out through pollen sampling on the body of hummingbirds. The limited change in species interactions highlights that network stability through interaction rewiring may have been overestimated in previous studies, calling for further manipulative studies in the field. At the same time, it also indicated that even the loss of a highly abundant plant species has an overall small effect on network structure. Thus, this study contributes timely findings regarding the capacity of ecological communities to respond to species extinctions.

Can the examination of different types of hive samples be a non-invasive method for detection and quantification of viruses in honey bee (Apis mellifera L.) colonies?

Honey bee viruses have been shown to negatively affect the vigour and longevity of European honey bees (Apis mellifera L). In the present work, beehive materials were tested for their potential to serve as non-invasive samples for honey bee virus detection. Honey, pollen, hive debris, hive grid smears and forager honey bees were collected from 24 hives at four locations in the Czech Republic. Deformed wing virus (DWV), acute bee paralysis virus (ABPV), sacbrood virus (SBV) and black queen cell virus (BQCV) were detected using a reverse transcription PCR (RT-PCR) and real-time quantitative RT-PCR and the results for bees and alternative materials compared. All forager bee samples contained DWV, BQCV and SBV and 54.2% had ABPV. When comparing beehive materials to bees, the most promising results were obtained from honey and pollen samples, with BQCV and SBV detected in all honey samples and ABPV in 12.5%. Detection of SBV was achieved in 91.6% of pollen samples, detection of BQCV in 87.5% and detection of DWW in 75%. The results for debris and smears were less consistent with the viral profile of the forager samples. The best candidate materials for honey bee virus detection in a non-invasive technique are honey and pollen.

Proximate, nutritional, phytochemical and stability analysis of stingless bee pollen from Sarawak, Malaysia

Bee pollen, as one of the products of bees, is often claimed as nature’s most complete food. The present work aimed to evaluate and compare the physicochemical properties, proximate composition, and phytochemical content of stingless bee pollen Heterotrigona itama from eight different geographical origins in Sarawak, Malaysia. Storage studies of the stingless bee pollen samples at four different temperatures were also conducted. The pH and water activity of the pollen samples were in the range of 3.45 to 3.69 and 0.39 to 0.51, respectively. Pollen samples contained 51.96% carbohydrates, 16.31% protein, 4.85% lipid, and 2.24% minerals on average. In addition, the total phenolic content (TPC) and antioxidant activity of pollen extracts ranged from 27.99 to 63.17 mg GAE/g and 66.73 to 94.03% radical scavenging activity, respectively. The phytochemical screening test revealed that saponin, terpenoid, and flavonoids were present in all the pollen extracts under investigation. Processed bee pollen is relatively stable at a storage temperature of or below 40 °C. In addition, no obvious degradation in terms of protein content, TPC or antioxidant scavenging activity was observed, even at an incubation temperature of 50 °C. The results of the present study indicated that processed stingless bee pollen of Sarawak origin is a natural product that could last a long time at an ambient temperature of 25 °Cin addition to its good source of nutritional and bioactive compounds.

Palynotaxonomy of Calea sect. Meyeria (Asteraceae: Neurolaeneae)

Calea comprises 157 species that occur in the Neotropics. The genus is organized into eight subgenera and 18 sections. Calea sect. Meyeria consists of eight species occurring exclusively in south-central Brazil. In this study, pollen grains from these eight species were sampled from herborized flower buds in pre-anthesis. Pollen samples were acetolyzed, measured, and photographed under a light microscope. Unacetolyzed pollen grains were examined under a scanning electron microscope. The results were used to characterize pollen morphology and construct a palynotaxonomic key for Calea sect. Meyeria. The analyzed pollen grains were monads, isopolar, usually medium-sized, oblate spheroidal, tricolporate, with lalongate endoaperture, the sexine echinate and thicker than the nexine, and six spines in the apocolpium region. The eight species have very similar pollen grains, but some characters are informative for this section, namely pollen size, polar area, sexine ornamentation, and endoaperture characteristics. Despite the similarity of the pollen grains, palynological analysis was able to contribute to the delimitation of Calea species, providing new information for species distinction within Calea sect. Meyeria.