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.

This study presents morphological descriptions and ecological information for 58 terrestrial pollen taxa and seven water-related pollen taxa from the Brazilian Cerrado, obtained from two sediment cores, Lake Feia (LFB1) and Getulio Swamp (VGE-17), encompassing the last 5000 and 15,000 cal yr BP, respectively. The relationships between the ecological and morphological traits (pollination syndrome, vegetation stratum and grain size) within each of the two depositional environments were investigated. In the LFB1 core, the pollen assemblages were dominated by arboreal pollen from closed physiognomies and lower storey trees (<10 m in height), while a combination of closed and open physiognomies was observed in the pollen assemblages from the VGE-17 core. The vast majority of the pollen taxa exhibited the entomophilous pollination syndrome, and a higher influx of entomophilous pollen was observed in both cores. Anemophilous and anemophilous/entomophilous syndromes were less well represented. Small and medium pollen grain classes were the most abundant, while the large pollen grain class was rare. The influx of small pollen grains was slightly more abundant in the lake record, while in the swamp record medium pollen grains were more abundant. Our results show that swamps and lakes differ in their representation of local versus regional pollen and in their sensitivity and responses to water-level changes. Landscape physiognomy also influences pollen dispersion: a closed physiognomy increases the local pollen signal, while a more open physiognomy results in better representation of local and regional signals.

The palynological (palynostratigraphical/palynofacies) analysis of samples from the Middle Jurassic outcrop at the Quebrada Álvarez section located in the Neuquén Basin, Patagonia, Argentina, allowed us to begin to evaluate the palaeoecological significance of the recovered palynofloras and their importance in the evolution of these ecosystems, during the transition between the uppermost Cuyo Group and the lowermost Lotena Group. The Lajas Formation, characterised by the palynofacies type A, could be interpreted as a tide-modified delta front environment. The high abundance and diversity of the palynomorphs identified in the studied samples, contribute to improve the palynological knowledge of the Challacó Formation (palynofacies type B – F). Considering the palaeoecological requirements of the recognised plant families, relatively humid and warm climate conditions could be inferred during the deposition of this unit. Also, the ‘seasonally dry (winterwet)’ biome was interpreted for the first time in the Neuquén Basin. Based on selected key taxa a late Bathonian–early Callovian age is proposed for the Challacó Formation at the Quebrada Álvarez section. The palynological material recorded in this unit suggests the development of a lacustrine environment with cycles of relative contraction and expansion of the water body due to fluctuations between relatively dry and wet conditions. The dominance of phytoclasts, mainly opaque particles, and freshwater algae (Botryococcus) in the Bosque Petrificado Formation (palynofacies type G – I) could suggest the development of a freshwater to brackish lacustrine environment. Based on the dominance of the same group of palynomorphs (chlorophyte algae) in the Challacó and Bosque Petrificado formations, similar palaeoenvironmental conditions would be inferred for these units. From a lithofacies analysis point of view, the Challacó and Bosque Petrificado formations show isopic facies associations in the study locality.

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.

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.

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.

Our study focused on the pollen morphology of 13 species of Matthiola and the closely related genus Dvorakia. We used light and scanning electron microscopes to examine the importance of pollen characteristics in classifying these genera. Pollen grains were acetolysed, measured, photographed, and described based on qualitative and quantitative characteristics. Here, we present statistical analyses and multivariate statistics for quantitative data. Pollen in both genera are tricolpate and varies in shape from subprolate to prolate. We distinguish two pollen types based on lumen width. Matthiola pollen has both reticulate and macroreticulate ornamentation, while Dvorakia alyssifolia pollen is reticulate. The thickness of the exine and the width of the mesocolpium are important traits in addition to exine ornamentation. Iranian Dvorakia and Matthiola species' pollen size can be divided into four types, one of which is Type I (Dvorakia alyssifolia type). Among the examined species, M. tomentosa has the smallest pollen grains, while D. alyssifolia has the largest grains. Pollen morphology confirms the transfer of D. alyssifolia from Matthiola to Dvorakia. Additionally, we propose a species key for the genera.

The exine ultrastructure of 18 species of Anisopappus (Anisopappinae, Athroismeae, Asteraceae) and three species of Duhaldea (Inuleae, Asteraceae) was studied using transmission electron microscopy (TEM). Two ultrastructural patterns were identified: senecioid and helianthoid. The senecioid pattern is characteristic of the species included in the basal clades of the phylogenetic tree of Anisopappus, as published in earlier studies. The helianthoid pattern is restricted to the taxa placed in the derived clades, including the core group of species of Anisopappus in which A. chinensis, the type species, is included. The observed ultrastructural differences seem to suggest that a future splitting of Anisopappus into several different genera should not be disregarded and that the helianthoid pattern represents, within this genus, the derived condition. The ultrastructure of the exine supports the inclusion, suggested by previous authors, of the species Duhaldea stuhlmannii, but not that of Philyrophyllum schinzii, in Anisopappus. In contrast, the three studied species of Duhaldea (D. cappa, D. nervosa, D. revoluta) present an exine with a senecioid pattern, which is characteristic of the tribe Inuleae, in which they are included. The ectoaperture, mesoaperture, and endoaperture of all studied Anisopappinae and of Duhaldea respectively intersect the tectum plus columellae, the foot layer and the outer part of the endexine, and the inner part of the endexine. This feature seems to characterize, in a consistent way, the ‘Heliantheae alliance’, and is also present in all the studied Asteroideae (except Anthemideae), Dicomoideae, and Carduoideae.

This article presents a pollen study of 13 species of Dendrophorbium (Asteraceae: Senecioneae) occurring in Brazil. Dendrophorbium has species distributed in the South and Southeast regions of the Brazilian territory that were previously grouped in Senecio Myriocephalus sect. and later Dendrophorbium was elevated to the rank of genus, considering the section Myriocephalus as a synonym of Dendrophorbium. The aim of this study is to advance knowledge of the pollen characteristics of the genus and thus contribute to the taxonomy of the group. The botanical material was collected from specimens deposited in national herbaria. Floral buds were acetolysed for light microscopic analysis. Pollen sediments were mounted on slides with glycerinated gelatin and analyzed under a light microscope. Measurements were taken of the diameters and thickness of exine layers of pollen grains. Examination showed pollen grains to be monadic, isopolar, medium-sized, oblate-spheroidal to pro-late-spheroidal, and 3-colporate. The endoaperture has median constriction in most species, except in D. pellucidinerve. The sexine is thicker than the nexine and echinate, with large perforations at the base of echinae. The exine is caveate. Based on the results, it can be concluded that the pollen grains of the 13 Dendrophorbium species are homogeneous and can be differentiated by aperture shape and dimensions and echinus characteristics.

Astragalus L. sect. Aegacantha Bunge includes 57 described species, mostly confined to Southwest Asia and Central Asia. We studied the pollen morphology of 17 species of this section present in Pakistan. Pollen morphology of sect. Aegacantha species is poorly investigated despite its systematic importance. The main aim of this study is to determine and document the pollen characters that can assist in the taxonomic identification of species in this difficult section. Pollen slides were prepared following acetolysis and examined by both light and scanning electron microscopy. Pollen size varies, with the polar axis ranging from 32.91 to 43.10 µm and the equatorial axis from 22.91 to 28.47 µm. Pollen is sub-prolate (1.15–1.33) to prolate (1.34–2.00) in shape, small to medium in size, radially symmetrical, isopolar, trizonocolporate to tricolporate, and monad. Sculpture variations (i.e. reticulate, microreticulate, perforate, microperforate, regulate, microregulate and granulate) were observed around the apertural, meridional and polar regions. Ordination analysis (principal component analysis (PCA)) revealed that the quantitative characters of pollen morphology are the most reliable characters for delimitation of species within section Aegacantha. Cluster analysis (unweighted pair group method using arithmetic average (UPGMA)) shows a partial relationship between the Aegacantha taxa clustered based on pollen characters and supports the general morphology. Further, this study shows that the pollen traits provide a baseline for phylogenetic optimisation in the investigated Aegacantha section.

Plebeia mansita is a native stingless bee endemic to the Yungas whose populations are distributed in sectors above 1000 m a.s.l. Its honeys and other products are used by local residents for various purposes, from food to medicinal uses. With the purpose of understanding the botanical resources that contribute nectar and nesting to this species of bee in the town of Baritú (22°28′54.1″S, 64°45′39.4″W; at 1546 m a.s.l.), we analyzed 41 honey samples collected between September 2011 and September 2015 and recorded the main host trees. The samples were examined by palynological techniques using acetolysis, revealing the use of pollen types belonging to native plants, mainly of arboreal habit. Pollen richness per sample varied from 13 to 31 pollen types (mean = 22.7), where the family Asteraceae had the highest number of pollen types (n= 9) and nectar relevance, followed by Myrtaceae. Relevant pollen types correspond to Blepharocalyx salicifolius, Ilex argentina, Myrcianthes pseudomato and Allophylus edulis, followed by Sambucus peruviana, Parapiptadenia excelsa, Handroanthus lapacho, Myrsine coriacea and Zanthoxylum. Other recorded pollen types, with importance index values below 3.5% were Eupatorium, Dendrophorbium bomanii, Senecio, Pseudognaphalium and pollen of the families Asteraceae and Rhamnaceae. On the other hand, when evaluating nesting substrates we recorded the frequency of use of trunks of Ilex argentina as 55.9%, Parapiptadenia excelsa 10.3%, Myrcianthes pungens 7.4%, M. pseudomato 5.9%, Juglans australis 4.4%, Handroanthus lapacho 2.9%, and Blepharocalyx salicifolius, Myrsine coriacea, Ocotea porphyria, Viburnum seemenii, Myrcianthes mato, Roupala montana var. brasiliensis and Erithrina falcata with a value of 1.5% each. The results obtained provide valuable information on the plants that provide nectar and nesting sites for this stingless bee. This information should be considered for the preparation of conservation or production plans for their hives and pollination activities.