Pollen morphology of the Phyllanthus species occurring in the continental United States

Twelve native United States species have been examined. The pollen grains could be divided into five pollen types based on sexine ornamentation, aperture structure, sexine/nexine ratio and sexine 1/sexine 2 ratio. Within these types it was often possible to distinguish the grains of the different species. Two groups of types have been recognized based on the similarities in ornamentation. One group, consisting of the Phyllanthus amarus type, the P. tenellus type and the P. urinaria type, is characterized by the Tilia structure, whereas the second group of types, comprising the P. caroliniensis type and the P. liebmannianus type are microreticulate. The postulation that different subgenera show different pollen types is true in general, but there is one exception: P. niruri, taxonomically belonging to the subgenus Phyllanthus, has pollen grains of the P. caroliniensis type, a type also comprising species from the subgenus Isoclades.     

Analysis of airborne allergenic pollen spectrum for 2009 in Timişoara, Romania

The objective of this investigation was to identify the overall pollen types and, more particularly, the allergenic pollen content in the investigated area and then to explore their seasonal variations. The measurement point was located in the Timi?oara city, Romania. A Lanzoni volumetric trap was used for sample collection. Duration of the pollen season of allergenic plants and respective variation in airborne pollen concentration are presented in the pollen calendar for the year 2009. Among the identified pollen of 23 types, 20 were allergenic: Taxaceae/Cupressaceae, Alnus sp., Fraxinus sp., Betula sp., Corylus sp., Carpinus sp., Salix sp., Populus sp., Ulmus sp., Juglans sp., Quercus sp., Pinaceae, Tilia, Poaceae, Urticaceae, Chenopodiaceae/Amaranthaceae, Rumex sp., Plantago sp., Artemisia sp., Ambrosia sp. These species prevail throughout almost the entire pollen season, from February–October, accounting for 87.03 % of the total pollen count. The greatest diversity of pollen types is detected in the months of spring. The summer months were characterized mostly by non-arboreal pollen types. In late summer and early autumn, Ambrosia airpollen was the most abundant in the atmosphere. The relationships between pollen concentrations and nine meteorological parameters are presented too. To analyze the correlation between pollen data and variables, the Spearman rank correlation coefficient was used. The correlation analysis of daily pollen counts and meteorological parameters showed that arboreal pollen and non-arboreal pollen counts were significantly correlated with temperature. The prevalence of pollen sensitization resulted to be very high in our patients with respiratory symptoms.     

Revision of the relationship between anther morphology and pollen sterility by cold stress at the booting stage in rice

Background and AimsCold stress in rice (Oryza sativa) plants at the reproductive stage prevents normal anther development and causes pollen sterility. Tapetum hypertrophy in anthers has been associated with pollen sterility in response to cold at the booting stage. Here, we re-examined whether the relationships between anther abnormality and pollen sterility caused by cold stress at the booting stage in rice can be explained by a monovalent factor such as tapetum hypertrophy.MethodsAfter exposing plants to a 4-d cold treatment at the booting stage, we collected and processed anthers for transverse sectioning immediately and at the flowering stage. We anatomically evaluated the effect of cold treatment on anther internal morphologies, pollen fertilities and pollen numbers in the 13 cultivars with various cold sensitivities.Key ResultsWe observed four types of morphological anther abnormalities at each stage. Pollen sterility was positively correlated with the frequency of undeveloped locules, but not with tapetum hypertrophy as commonly believed. In cold-sensitive cultivars grown at low temperatures, pollen sterility was more frequent than anther morphological abnormalities, and some lines showed remarkably high pollen sterility without any anther morphological alterations. Most morphological anomalies occurred only in specific areas within large and small locules. Anther length tended to shorten in response to cold treatment and was positively correlated with pollen number. One cultivar showed a considerably reduced pollen number, but fertile pollen grains under cold stress. We propose three possible relationships to explain anther structure and pollen sterility and reduction due to cold stress.ConclusionsThe pollen sterility caused by cold stress at the booting stage was correlated with the frequency of entire locule-related abnormalities, which might represent a phenotypic consequence, but not a direct cause of pollen abortion. Multivalent factors might underlie the complicated relationships between anther abnormality and pollen sterility in rice.     

Pollen morphology in relation to floral types and pollination syndromes in Pedicularis (Orobanchaceae)

Floral diversification in the genus Pedicularis (Orobanchaceae) is remarkable among flowering plants. In this genus, floral morphology and pollinator behavior are closely co-adaptive. In the current paper, pollen grains of 23 representative species of Pedicularis mainly from North America, with two species from Japan and two species from China, whose pollination ecology was previously studied, were examined using light microscopy and scanning electron microscopy. Two pollen aperture types and three kinds of exine ornamentation were recognized among these species. In addition, pollen data from previous and the current studies of Pedicularis were integrated and analyzed, together with some pollination characters. There was a significant association between pollen aperture types and corolla types, as well as between pollination syndromes and corolla types. However, there was no association of exine ornamentations with corolla types. The relationships and evolution of this genus were discussed with regards to pollen morphology, corolla types and pollination syndromes.     

Floral Preference of Melipona eburnea Friese (Hymenoptera: Apidae) in a Colombian Andean Region

Melipona eburnea Friese is a stingless bee kept in some regions of Colombia, where it is reported to be vulnerable to extinction due to habitat disturbance. To contribute to raising conservation strategies, the aim of this study was to identify the floral preferences of this species using melissopalynological analysis. A total of 31 pollen pot samples and 37 honey samples were taken from March 2009 through March 2010 from four colonies in Fusagasuga, Colombia. We found 92 pollen types: 17 from pollen pot samples, 39 from honey samples (indicating the sources of nectar), and 36 in both types of samples. The most frequent pollen types in the pollen pot samples were Myrcia type (100%), Eucalyptus globulus (96.9%), and Fraxinus uhdei (96.9%). The most frequent pollen types in honey samples were E. globulus (97.4%) and Myrcia type (94.9%). The pollen types corresponded mainly to native plants (68%), trees (44.5%), plants whose sexual system is hermaphroditic (56.5%), and plants with inflorescences (76.2%). The most frequent shapes of the flowers were brush-like (type Myrtaceae) and dish-like (type Asteraceae), and the preferred flower colors were white or cream (52.2%). In general, we found that M. eburnea showed a strong preference for trees of the family Myrtaceae to obtain nectar and pollen, including native and introduced species. Some other families are contributing significantly, such as Melastomataceae for pollen collection and Asteraceae for nectar. These results highlight the key plant species for the diet of M. eburnea.     

The systematic value of pollen morphology in Smilacaceae

Smilacaceae are a small family of dioecious, mostly climbing, net-veined monocotyledons with a cosmopolitan distribution. Relatively little is known about the variation of pollen morphology within the family. For this reason, and to investigate the systematic value of palynology in Smilacaceae, pollen from 125 species of Smilax, Heterosmilax, and Ripogonum was examined using light and scanning electron microscopy. Ten of these were examined further by transmission electron microscopy. Four distinct pollen types grouped into two major pollen classes were distinguished: Class 1, represented by the pollen of all Smilax and Heterosmilax species, is mostly spheroidal, inaperturate, and spinulate or microspinulate, with a thin, fragile exine of varied sculpturing; three pollen types are represented within this class. Class 2 is found only in Ripogonum and contains a single pollen type with prolate, monosulcate, reticulately-sculptured pollen. The unique pollen morphology of Ripogonum supports its removal from Smilacaceae. In contrast, the characteristics of Heterosmilax pollen intergrade with those seen in Smilax, suggesting that the former might be better reduced to synonymy with the latter. A key to the identification of these pollen types is presented along with a discussion of geographic and possible evolutionary trends among them.     

Secondary pollen types characteristic of Louisiana honeys

Nine secondary pollen types (those comprising 16–45% of the pollen sample) were recovered from 54 honey samples (10 g) collected from the major beekeeping areas of Louisiana. The pollen types in order of decreasing importance are:Berchemia scandens, rattan vine;Rubus spp., blackberry and dewberry;Salix spp., willow;Trifolium repens, white clover;Glycine max, soybean;Parthenocissus quinquefolia, Virginia creeper; Rosaceae, rose family;Cephalanthus occidentalis, buttonbush; andCornus spp., dogwood. The first four secondary types also appeared as dominant pollen (over 45%) in some of the Louisiana honey samples investigated and were previously reported. The remaining five pollen types and the “bee plants” associated with each pollen type are identified and described.     

Botanical affinity of pollen harvested by Apis mellifera L. in a semi-arid area from Bahia,Brazil

We analysed the botanical composition of pollen harvested by Apis mellifera L. in the Canudos Biological Station, Bahia, Brazil, and the influence of climatic factors on pollen sample composition was assessed. Forty-six pollen types were identified belonging to species occurring in the study area. The family Leguminosae was of significant importance amongst the samples, represented by ten pollen types. Diodia radula, Rhaphiodon echinus, and Mimosa misera pollen types occurred most constantly among the samples. We observed that isolated pollen class characterises samples analysed. It was also observed that pollen type richness is directly linked to rainfall, reflecting the strong influence of this climatic parameter on flowering intensity, and thus on the ability of the bees to obtain food resources.     

Pollen morphology of the tribe Rhinantheae (Orobanchaceae) and its systematic significances

Pollen morphology of 36 species representing 14 genera within the tribe Rhinantheae in the family Orobanchaceae was studied and illustrated with light microscopy (LM) and scanning electron microscopy (SEM). Five major pollen types were recognized on the basis of exine ornamentation. Within these major types, minor types (subtypes) were distinguished based on exine surface pattern, size, shape, amb form, colpi and colpus membrane. These types and subtypes are as follows: type I. retipilate: subtype Ia. regular retipilate: (1) pollen size < 27 μm, (2) pollen size > 27 μm, subtype Ib. irregular retipilate; type II. verrucate: subtype IIa. macro-verrucate, subtype IIb. verrucate, subtype IIc. sparse verrucate; type III. retirugulate; type IV. granulate; type V. micro-reticulate. A key to pollen morphology of genera studied within the Rhinantheae was made based on pollen morphology from our study and earlier work. Combining with other sources of information on the Rhinantheae, the systematic relationships of this tribe are discussed. Rhinantheae pollen displays considerable variation between genera and species, with taxonomically significant characters at genus and species level. Palynological characteristics provide evidence for interpreting the conflicting views concerning the “Pterygiella Complex”. The evolutionary trend in exine sculpture of Rhinantheae could be proposed, namely that retipilate sculpturing which is the most widespread type is more primitive than the other types (such as foveolate, granulate, regulate, reticulate, retirugulate and verrucate). The pollen data in present study and the view of Hong (1986), as well as the molecular data from Bennett and Mathews (2006) indicated that Asia and related regions were likely to the origin centre of the tribe Rhinantheae.     

Palynological survey of the subtribe Elephantopinae (Asteraceae, Vernonieae)

Despite the taxonomic value of pollen morphology within the tribe Vernonieae, a detailed study of the pollen of the subtribe Elephantopinae is still lacking. The pollen morphology of ten species, representing three of the four genera of the subtribe, Elephantopus, Pseudoelephantopus and Orthopappus, was studied with LM, SEM, and TEM. The pollen of all the species studied was found to be echinolophate, although the differences in aperture features and both sculpture and exine structure allowed recognizing two pollen types. The species of Elephantopus (except for E. elongatus) and Pseudoelephantopus share the regular or more or less regular ridges pattern, the colporate condition but with the ectoapertures little developed, and the acaveate exine structure. From the sculpture and the apertures, the pollen of Caatinganthus harleyi was found to be similar to that of Elephantopus and Pseudoelephantopus. The pollen morphology of the monotypic Orthopappus, which is shared with that of E. elongatus, was further investigated for the first time. We found that it differs from that of the other species in having an irregular pattern of ridges, colporate condition but with a well-developed ectoapertures, and caveate exine. Additional studies of the exine structure and apertures features, coupled with molecular phylogeny, are needed to understand the evolution of pollen characters and re-evaluate the intergeneric relationships within the tribe.     

Pollen morphology of the genus Euphrasia L. (Orobanchaceae) from Pakistan and Kashmir and its taxonomic significance

Pollen morphology of 25 species of the genus Euphrasia L., belonging to the family Orobanchaceae from Pakistan has been examined by light and scanning electron microscope. It is a stenopalynous genus. Pollen grains are usually radially symmetrical, isopolar, tricolpate, sub-prolate to prolate-spheroidal rarely oblate-spheroidal. Sexine slightly thinner than nexine or as thick as nexine. Tectum coarse to fine retipilate or rugulate–retipilate. On the basis of exine ornamentation three distinct pollen types viz., Euphrasia foliosa, Euphrasia multiflora, and Euphrasia incisa are recognized. Pollen morphology is significantly helpful at specific level within the pollen type.     

Detection of the impact of early Holocene hunter-gatherers on vegetation in the Czech Republic, using multivariate analysis of pollen data

Pollen data from the Czech Republic was used to detect the early Holocene impact of hunter-gatherers on vegetation based on a selection of 19 early Holocene pollen profiles, complemented with archaeological information regarding the intensity of local and regional Mesolithic human habitation. Archaeological evidence was assigned to simple categories reflecting the intensity of habitation and distance from pollen sites. Multivariate methods (PCA and RDA) were used to determine relationships between sites and possible anthropogenic pollen indicators and to test how these indicators relate to the archaeological evidence. In several profiles the pollen signal was influenced by local Mesolithic settlement. Specific pollen types (e.g. Calluna vulgaris, Plantago lanceolata, Solanum and Pteridium aquilinum) were found to be significantly correlated with human activity. The role of settlement proximity to the investigation site, the statistical significance of pollen indicators of human activity, as well as the early occurrence of Corylus avellana and its possible anthropogenic dispersal, are discussed.     

Pollen morphology of Diosma and Coleonema (Rutaceae: Diosminae) and its taxonomic implications

The pollen morphology of Diosma and Coleonema of the taxonomically problematic subtribe Diosminae (Rutaceae) was investigated to determine its taxonomic relevance. Pollen of 26 of the 28 species of Diosma and of each of the eight species of Coleonema was investigated by LM, SEM and TEM. In pollen of Diosma the exine sculpturing is uniform, and only one pollen type, reticulate, could be distinguished. In contrast, exine sculpturing shows interspecific variation in Coleonema and three distinct types, striate, reticulate and perforate, could be discerned. Species groupings indicated by the pollen types suggest possible relationships between species within Coleonema and with other genera that were not previously apparent. Pollen data support macromorphological evidence that suggests the generic re-classification of the Diosminae.     

Pollen morphology and systematics of Burseraceae

The Burseraceae are a medium‐sized family in which 18 genera are currently recognised. They are the subject of a long‐term project to describe the pollen morphology from light, scanning electron and transmission electron microscopy. The pollen morphology of tribe Protieae has been published, as well as an account of the pollen of the African taxa in the family. Pollen data for the other two tribes, Bursereae and Canarieae, are more or less complete. The pollen of all the genera have been examined, with the exception of the recently described Pseudodacryodes Pierlot for which, currently, there is no pollen material available. This paper summarises the results.

There is considerable variation in exine and aperture features between, and occasionally within, the genera and 14 major pollen types are defined, including two previously undescribed types: ‘Canarium oleiferum’ and ‘Canarium gracile’. The distribution of pollen characteristics throughout the family is compared with previously published tribal and subtribal groupings, as well as with current ideas of generic relationships from molecular analyses. Comparisons show notable congruence of pollen data with molecular data. To some extent pollen morphology is different for each of the subtribes. Nevertheless, there are some notable exceptions, for example, the pollen of Garuga and Boswellia are remarkably similar, although Garuga has been included, somewhat tenuously, in tribe Protieae, and Boswellia is included in tribe Bursereae, subtribe Boswelliinae. In a recent molecular tree Garuga and Boswellia appear to be closely related, and this supports the conclusion, based on several macromorphological characters as well as pollen, that Garuga should be transferred to tribe Bursereae.     

Types of Artemisia pollen season depending on the weather conditions in Wrocław (Poland), 2002–2011

The aim of the study was to characterise Artemisia pollen season types according to weather conditions in Wroc?aw (south-western Poland) in the years 2002–2011. Over the period analysed, the start date of the pollen season (determined by the 95 % method) ranged from 10 July 2002 to 28 July 2010. The start date of the pollen season can be determined by using Crop Heat Units (CHUs). During the period 2002–2011, the Artemisia pollen season started after the cumulative value of CHUs had reached 2,000–2,100 °C. The three distinguished types of Artemisia pollen season are best described by the frequency of weather types defined by the type of circulation, mean daily air temperature, and the occurrence of rain. The variation in these factors affected the dynamics of the pollen season. The noteworthy frequency of days with rain and high seasonal sum of precipitation totals as well as the dominance of cyclonic weather from the westerly direction had an impact on the extension of the pollen season. The meteorological factors that directly affect pollen release and transport primarily include air humidity, expressed as vapour pressure (r > 0.3, p < 0.01), temperature(r from 0.2 to 0.4, p < 0.01). The relationships between averaged meteorological data and daily pollen concentration were stronger (r > 0.5, p < 0.01). Based on the correlation analysis, the meteorological variables were selected and regression equations were established using stepwise backward regression analysis.     

Pollen morphology and taxonomy of the subtribe Diocleinae (Leguminosae: Papilionoideae: Phaseoleae)

The pollen morphology of the thirteen genera currently included in the subtribe Diocleinae is described. Nine pollen types with a number of subtypes are recognized. These are arranged into two main groups. The first comprises the macromorphologically anomalous genera Calopogonium, Herpyza and Pachyrhizus which, although united by some pollen characters, are distinct both from each other and from the rest of the subtribe. The second group, consisting of the remaining genera which can to some extent be distinguished from each other by their pollen morphology, nevertheless appear to make up both macromorphologically and palynologically a more natural Diocleinae. The six pollen types in the second group are further divided into two slightly overlapping subgroups. Luzonia and Macropsychanthus are palynologically somewhat distinct but, together with Dioclea and Canavalia, have generally rather large, oblate pollen grains with a complete or perforate tectum, in contrast with the pollen of the genera Camptosema, Collaea, Cratylia and much of Galactia which is smaller, spheroidal with a reticulate tectum.Dioclea has some species with isopolar pollen and others with heteropolar pollen grains and this more or less correlates with subgeneric divisions within the genus. Galactia from the Caribbean area has similar but much smaller pollen. The taxonomic significance of this parallel between the pollen morphology of Dioclea and Caribbean Galactia is unclear. The pollen of Canavalia appears to show no significant variation.A possible correlation between the pollen subgroups with ecological habitat and pollinators is discussed.     

Utility of Surface Pollen Assemblages to Delimit Eastern Eurasian Steppe Types

Modern pollen records have been used to successfully distinguish between specific prairie types in North America. Whether the pollen records can be used to detect the occurrence of Eurasian steppe, or even to further delimit various steppe types was until now unclear. Here we characterized modern pollen assemblages of meadow steppe, typical steppe and desert steppe from eastern Eurasia along an ecological humidity gradient. The multivariate ordination of the pollen data indicated that Eurasian steppe types could be clearly differentiated. The different steppe types could be distinguished primarily by xerophilous elements in the pollen assemblages. Redundancy analysis indicated that the relative abundances of Ephedra, Tamarix, Nitraria and Zygophyllaceae were positively correlated with aridity. The relative abundances of Ephedra increased from meadow steppe to typical steppe and desert steppe. Tamarix and Zygophyllaceae were found in both typical steppe and desert steppe, but not in meadow steppe. Nitraria was only found in desert steppe. The relative abundances of xerophilous elements were greater in desert steppe than in typical steppe. These findings indicate that Eurasian steppe types can be differentiated based on recent pollen rain.     

The current status of medullosan seed ferns

The compression and permineralized fossil record of presumed medullosan plants is reviewed and evaluated. Recent studies of stelar architecture suggest that stems are monostelic rather than polystelic as commonly believed. Imparipinnate fronds are mostly of the Neuralthopteris/Alethopteris type with Myeloxylon anatomy; the affinity between medullosan stems and neuropterid fronds is uncertain. It is suggested that the reproductive organs of the family should be restricted to those pollen organs believed to have produced Monoletes pollen and to ovules, for the most part, of the Trigonocarpus/Pachytesta type. It is doubtful that reproductive organs replaced lateral pinnules; it is more likely that they terminated pinnae or were borne abaxially along the pinna rachis. In some cases they may have been borne directly on penultimate axes or were, as in Codonotheca and Goldenbergia, borne on fertile fronds or fertile portions of vegetative fronds. Recent research involving pollen organs is emphasized and a phylogeny of Monoletespollen organs is proposed. It is suggested that the fossil record of medullosans is best interpreted from a punctuational perspective.     

Dominant Pollen Types Recovered From commercial Louisiana honeys

Microscopical pollen analyses of 54 commercial honey samples collected from the major beekeeping areas of Louisiana during 1967–68 showed six dominant pollen types (a dominant type considered as one contributing over 45% of the total grains counted per sample and denoting a unifloral honey). The dominant pollen types and the “ bee plant ” species associated with each pollen type are identified and described. The pollen types are illustrated with light photomicrographs. The pollen types are in order of importance:Trifolium repens, white clover;Rubus spp., blackberry and/or dewberry;Berchemia scandens, rattan vine;Salix spp., willow; Asteraceae, Sunflower family; and Sapiumsebiferum,Chinese tallow tree. White clover and willow were the largest unifloral honey producers in a region including the floodplain and delta of the Mississippi River, and the floodplain of the Red River (the most productive beekeeping area of Louisiana); blackberry and/or dewberry were most significant in the longleaf pine flat woods and mixed hardwoods in the uplands section on the east side of the Mississippi River; rattan vine was most important in west-central Louisiana in an area consisting originally of pine-oak-hickory uplands and longleaf pine flat woods; white clover appeared most important in the prairie region of southwest Louisiana.     

A 10-year survey of allergenic airborne pollen in the city of Porto (Portugal)

Airborne pollen calendars are useful to estimate the flowering season of the different plants as well as to indicate the allergenic potential present in the atmosphere at a given time. In this study, it is presented a 10-year survey of the atmospheric concentration of allergenic pollen types. Airborne pollen was performed, from 2003 to 2012, using a 7-day Hirst-type volumetric trap. The interannual variation of the daily mean concentration of the number of pollen grains and the main pollen season was determined as well as the hourly variations and correlation with meteorological parameters. During the study period, 18 different allergenic pollen types were considered based on its representativeness on the total annual airborne pollen concentration. The lowest annual concentrations were sampled in 2006 and the highest in 2007. The highest airborne pollen concentration was found during early spring and early summer. On the contrary, December was the month with the lowest pollen concentration. The major pollen sampled belongs to trees followed by weeds and grasses, being the most representative pollen types in the atmosphere: Urticaceae, Platanus, Poaceae, Pinaceae, Cupressaceae, Acer, Quercus, Castanea, Plantago, Alnus, Olea europaea, Betula, Myrtaceae and Populus. Intradiurnal distribution patterns of the pollen types studied presented differences with some taxa being predominantly sampled in the morning (9–11 a.m.) while others in first night hours (between 9 and 12 p.m.). Significantly correlations were found between the airborne pollen concentration and meteorological parameters.