The present study addresses the pollen preferences of two species of wild bees of the genus Melissodes in the intensively farmed temperate Pampean region of Argentina. The resources used by M. (Ecplectica) tintinnans and M. (Ecplectica) rufithorax were studied in a commercial plot of sunflower and its field margins in the locality of Carlos Casares, province of Buenos Aires. Surveys before, during and after the bloom of sunflower were carried out. The bees emerged synchronously with the beginning of the bloom, but continued foraging for over a month after maturation of the crop. Pollen analyses of scopal loads indicated that sunflower was a major component of the diet. Bees also collected pollen from other Asteraceae during and after the blooming of the sunflowers. Pollen from Ligustrum sp. and Eucalyptus sp., two trees common in the hedgerows, was also collected in significant amounts. The vegetation on the field margins facilitated maintenance of the populations after the blooming of the sunflower. The two species of native Melissodes used pollen of plant taxa that are frequent and widespread in the Pampean agricultural ecosystems. This fact, together with their habit of nesting in aggregations, indicates that these bees represent a valuable resource as crop pollinators.

Burkard personal samplers for Petri dishes use two air throughput devices, either with a sieve or with a funnel, for monitoring of airborne fungi concentration. These two different methods have been compared in a comparative study. The two personal traps used for comparison were run simultaneously, one equipped with a sieve and one with a funnel only. Possible correlations with rainfall, temperature, wind speed, and relative humidity were studied. The average concentrations were 74 and 339 colony forming units/m3 (a factor of 4.6 difference) for the funnel and sieve devices, respectively. More than 70 taxa of airborne fungi were identified. The four most important genera in decreasing order of concentration were Cladosporium, Alternaria, Penicillium, and Aspergillus, the last two present in similar concentration. A significant negative correlation with wind speed was detected. Statistical analysis (ANOVA) revealed significant differences between the two sampler types except for Alternaria. In conclusion, the sampler with a sieve provides more colonies than the same sampler with a funnel. Both kinds of samplers are affected by wind speed, with the capture of airborne fungi propagules being reduced as the speed increases.

The epiphytic fern genus Serpocaulon (Polypodiaceae) comprises 42 species nested within the neotropical clade of the family together with genera such as Campyloneurum, Grammitis, Microgramma, Niphidium, Pleopeltis, Pecluma, Polypodium and Terpsichore. Although Serpocaulon is a well-supported genus, its intra-specific relationships are still not completely resolved. The morphological dataset for Serpocaulon and related genera is therefore expanded here with information on spore morphology to provide additional information for phylogenetic consideration. Spores have been collected from herbarium vouchers and acetolysed for light and scanning electron microscopy. All members of the neotropical clade have monolete spores, except for Grammitis and Terpsichore, which have trilete spores. Both verrucate and papillate ornamentation types are recognised. The palynological analysis shows close similarity between spores of Serpocaulon, Campyloneurum, Pleopeltis and Polypodium and supports close phylogenetic relationships between these taxa. Species of the grammitid clade, although nested within the Polypodiaceae, have spore morphology that supports a separate position.

The developmental events in microspores and the tapetum in Swida alba have been traced in detail. The first elements of the glycoprotein glycocalyx appear as hemispherical, elongated, and conical units, rooted in surrounding callose layer. These units are evidently transitional forms of spherical micelles. At the middle tetrad stage, these units (future columellae) acquire a cylindrical form and consist of clusters of radially oriented subunits (clusters of cylindrical micelles), twined round with a spiral element. At the late tetrad stage, procolumellae increase, and the tectum with microchannels is initiated at the interface of the callose and the glycocalyx layers. Cone-like ‘skeletons’ – typical crystal-like structures – of the future spines emerge on the tops of the columellae, and the primordial white-lined lamella appears as a demarcation line between the future foot layer and endexine. During disintegration of the tetrads, several new white-lined lamellae arise that are evidently formed on the base of laminate micelles with their typical gaps seen in transmission electron microscopy as white lines. After addition of the second granular layer of endexine, all the elements of exine become thick as a result of sporopollenin accumulation. The completion of sporoderm development is carried out after microspore mitosis by intine formation.

The microscopic analysis of honeys has led to the identification of different structures, including pollen grains, fungal spores, yeast, algae and soot particles. Pollen grains are the most studied elements, while others, like fungal spores and yeast, are less well known. Some of these elements come from primary sources and are associated with the presence of honey dew, such as Alternaria, Stemphylium, and Leptosphaeria. A variety of yeasts are regularly present in the floral nectar of many plant species where they frequently reach high densities. A melissopalynological method was used to identify some of these microscopic elements, their frequency in honeys and the relationships with the ecological origin of the product. The pollen types most frequently identified were Castanea sativa, Rubus, Cytisus type, Eucalyptus and Erica. Cladosporium conidia were identified in 64% of the samples, Metschnikowia cells were present in more than 50% of the honeys and some plant pathogenic fungi (Leptosphaeria, Stemphylium and Urediniospores among others) were also frequently present. The presence of Metschnikowia cells was associated with blossom honey and the presence of some fungal spores was associated with honey dew contributions.

Spore sculpture and wall structure of eight Cyathea (Cyatheaceae) species from southern South America were studied using light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Two layers, i.e. an inner and an outer layer, were observed in the perispore. The inner layer has two strata: the inner stratum is attached to the exospore and composed of rodlets tangentially oriented to the spore surface and randomly intermixed; the outer stratum consists of a three-dimensional network of rodlets with either free or fused distal edges forming spinules. The outer layer is thin, darkly contrasted and covers the rodlets. In most cases, the exospore has two layers and a pitted surface. In Cyathea atrovirens, the exospore surface is smooth, while in C. delgadii and C. myriotricha it is verrucate. The homogeneity of perispore features within the genus Cyathea is evident, while exospore features are heterogeneous. The exospore has different kinds of surface-structures that are of potential interest for assessing evolutionary trends within the group.

The pollen production per anther has been analysed in ten species of Chenopodiaceae that grow in the salt marshes of the Marismas del Odiel Natural Park (Huelva, south-west Spain). The mean pollen production per anther is 5819, ranged from 580 in Salicornia ramosissima to 12 467 in Salsola vermiculata, and is related to the size of the anthers. In six of the species, pollen production per anther has been studied in two populations and a strong interaction between species and populations was found. Pollen production of central and lateral flowers has been compared in four species, showing that central flowers produce significantly more pollen than lateral ones. In Arthrocnemum macrostachyum, a comparison between the pollen production of upper and lower stamens was performed and no significant differences were found. The pollen/ovule (P/O) ratio has been estimated for each of the species studied for the monoecious species, using the previously calculated male flower/female flower ratio. The monoecious species have the highest P/O ratios, followed by those with hermaphrodite flowers and allogamous reproduction. The lowest P/O ratios were found in Salicornia ramosissima (681) and Suaeda albescens (6025), possibly due to them being autogamous, which is consistent with the annual cycle and ecology of the species. The biggest value was found in the monoecious species Halimione portulacoides (88 405). In the remainder of the species, the P/O ratio depends on the density of individuals of each species in the communities.

For the detection of pollen wall layers, the use of different staining methods for one and the same species is highly recommended. The usage of standard transmission electron microscopy (TEM) staining methods showed that the ektexine-layers have always the same contrast behaviour, while the endexine changes its electron opaqueness depending on the method used. However, the endexine can often not be discriminated from the other wall layers. A simple method to detect the endexine is the use of potassium permanganate, which stains the layer electron dense, producing a distinct contrast.

The present study reports results of qualitative melissopalynological analyses of Finnish honey between the years 2000–2007 and changes in its pollen content from the period 1960–2007. Altogether the pollen content of 734 honey samples was analysed with an average of 415 pollen grains counted from a sample. Pollen of Trifolium repens type, Rubus spp., Salix spp. and the Brassicaceae family were present in more than 90% of the samples, and these pollen types were also found in the highest proportions. Annual variation in the relative amounts of the most numerous pollen types could be as high as 10%. On the basis of the pollen spectra of the honey samples, four regions of forage plants for bees could be identified in Finland. In the period between 1960 and 2007, the most marked change observed was that the percentage of the Trifolium spp. pollen type had decreased from 70% to 10%, while the proportions of Brassicaceae and Rosaceae pollen types showed a corresponding increase.

Palaua (Malvaceae) comprises 15 species endemic to the coastal deserts of Chile and Peru. Previous molecular phylogenetic analyses have shown that this genus is monophyletic and can be subdivided into three clades. In the present study, pollen morphology of all species of Palaua was examined using light and scanning electron microscopy to determine whether it provides additional data in support of the proposed infrageneric groups. The pollen grains are spheroidal, medium to large in diameter, spinose and pantocolporate – the ectocolpi are very short. The tectum is perforate and characterised by granula. In all species the nexine is of a similar thickness in all areas of the pollen grain, while the sexine thickness varies, being notably thicker in the areas where the broad spine bases are sited (‘spine cushions’). Many of the quantitative characters have conspicuous variability, but the variability shows considerable overlap between species. Nonetheless, P. guentheri, P. inconspicua, P. malvifolia and P. modesta are united as a group by having the smallest pollen grains with the smallest apertures, the shortest spines and the shortest interspinal distance. This grouping reflects only partially the suggested infrageneric clades, although it does tend to unite the species with the smallest flowers. A possible link between reproductive resources and pollen size is also considered, as well as the influence of polyploidy. However, the taxonomic utility of these quantitative characters is weakened by species with more than one cytotype.