Air pollen dispersal in a tropical area

Volumetric data on airborne pollen have been gathered for two consecutive years at a neotropical location (Caracas). Among the 65 taxa which were identified, pollen from aCupressus species (introduced) and from aCecropia species (indigenous) were dominant. Less numerous but also abundant (daily averages ≥5 grains/m³ air) were pollen from Gramineae, Urticaceae,Alcalypha, Pinus, Piperaceae andMimosa. Pollen grains were recorded daily throughout the year. They increased in numbers during April–May and again during November–December. The first peak was contributed mainly by indigenous species, the second peak mainly by introduced species.     

Analysis of airborne pollen fall in Sakarya, Turkey

In this study, pollen grains were identified using Durham sampler in the atmosphere of Sakarya in 2000 and 2001. During these two years, a total of 10 805 pollen grains were recorded. A total of 5 386 pollen grains per cm² were recorded in 2000 and a total of 5 419 pollen grains per cm² in 2001. Pollen fall in the years 2000–2001 comprised grains belonging to 40 taxa and some unidentified pollen grains. Of these taxa, 22 belonged to arboreal and 18 taxa to non arboreal plants. Total pollen grains consisted of 69.45% grains from arboreal plants, 28.11% grains from non-arboreal plants and 2.44% unidentified pollen grains. In the region investigated, Gramineae, Pinus sp., Quercus sp., Cupressaceae/Taxaceae, Salix sp., Platanus sp., Populus sp., Carpinus sp., Fagus sp., Chenopodiaceae/Amaranthaceae, Xanthium sp., Moraceae, Corylus sp., Fraxinus sp., and Urticaceae released the greatest amount of pollen. The season of maximum pollen fall was from March to May, with a prevalence of arboreal pollen in the first months, and of pollen from non-arboreal plants in the last months of the year.     

Pollen-mediated gene flow in Himalayan long needle pine (<Emphasis Type="Italic">Pinus roxburghii</Emphasis> Sargent)

Pollen migration in Pinus roxburghii has been estimated under two different conditions, viz. isolated single trees and at the fringe of natural forest. Trapping of pollen grains was conducted at geometrically increasing distances, i.e., 0, 5, 10, 20, 40, 80, 160, 320, 640, 1280 and 2560 m from the source. The observations revealed that the scattering of pollen grains was not uniform in all directions and that they travelled up to 2.5 km towards the downhill direction, while in the uphill direction dispersion of pollen grains was restricted to 320 m from the source. Pollen frequency declined rapidly as the distance from the source increased, with the highest densities within 50–100 m.     

Palynological study of the Venezuelan species of the genus <Emphasis Type="Italic">Hymenocallis</Emphasis> (Amaryllidaceae)

Pollen morphology and exine structure of the seven Hymenocallis Salisb. species present in Venezuela were investigated using scanning (SEM) and transmission (TEM) electron microscopy. Pollen grains of all species are monosulcate, heteropolar, with bilateral symmetry, oblate to peroblate, heterobrochate, semitectate-columellate, possess unequal tectal surfaces, and are clavate or baculate when viewed with TEM. They present two equatorial apexes. When observed under SEM their surfaces appear as granulate; however, it is evident from TEM that they are in fact constituted by pila. All the species possess very large pollen (ranging from 64 to 85 μm and from 125 to 155 μm for polar and equatorial axes, respectively), and no relationship was evident between pollen size and chromosome number. All the taxa are also very similar in relation to their pollen outline, ornamentation and internal structure, thus indicating that the genus is accurately delimited from the palynological point of view and that discrete characteristics can only be used in some cases to delimit individual species.     

Comparative pollen morphology of Glechoma and Marmoritis (Nepetinae,Lamiaceae)

Abstract The pollen morphology of 13 taxa (34 specimens) of the genera Glechoma L., and Marmoritis Benth. was investigated in detail using light, scanning electron, and transmission electron microscopy. Pollen grains of all studied taxa are small to large in size (P= 32.5–60.4 μm, E= 20.2–50.5 μm), prolate‐spheroidal to prolate in shape and mostly hexacolpate (the amb more or less circular or rarely ellipsoid) with granular membranes. The sexine ornamentation of Glechoma is bireticulate; the muri of the primary reticulum are irregularly circled, and lumen size is short. In contrast, the sexine surfaces of the Marmoritis pollen tend to more elongate or wider at the muri of the primary reticulum than those of the Glechoma. The pollen wall stratification of selected taxa (three from Glechoma and one from Marmoritis) is characterized by unbranched columellae, and continuous or distinctly discontinuous endexine based on transmission electron microscopy observation. The results of Glechoma and Marmoritis reveal rather similar pollen morphological features, however, fine details of sexine ornamentation are characteristic to differentiate the pollen taxa. Although these differences may be useful in establishing the taxonomic boundary between two genera, they are too weak to segregate diagnostic characters.     

Airborne pollen sampling in Toledo, Central Spain

Toledo is one of the main tourist spots of Spain, attracting around two million visitors per year. Its geographical situation in the vast and scarcely monitored Region of Castilla La Mancha and the high number of tourists (especially in the spring) has resulted in the Spanish Aerobiology Network (REA) making this city a major study objective. Air monitoring studies carried out using REA sampling procedures commenced in October 2002. Thirty-two pollen types were identified during the sampling period (October 2002 to October 2004). The annual Pollen Index (PI) was 44124 for the agricultural year October 2002–October 2003, and 29666 in the same period of 2003–2004. The most abundant taxa were, in decreasing order of dominance: Cupressaceae, Quercus, Poaceae, Populus, Olea, Urticaceae, Platanus, Pinus and Ulmus. Other, less well-represented pollen taxa included Salix, Alnus, Fraxinus and Tamarix, which were characteristic of riverside areas, and Morus, Artemisia and Chenopodiaceae. The presence of Castanea pollen grains originating from chestnut crops far away from the city was clearly an example of long-distance transport. The highest concentrations of airborne pollen were detected from March to May and also in January, due to the flowering of Cupressaceae species. In general, there was a correlation between pollen and meteorological parameters: a positive correlation with temperature and a negative correlation with rainfall and humidity during the pre-peak period. A negative correlation between temperature and some tree pollen taxa was detected in the principal pollen period correlation analysis due to their long pollination periods.     

Pollen morphology and localization of Ni in some Ni-hyperaccumulator taxa of Alyssum L. (Brassicaceae)

Pollen morphology of seven Alyssum L. taxa growing on serpentine soils in different places in the European Mediterranean macrobioclimate territory were studied, described and compared. Cluster analysis was performed to show similarity between species and their populations. The shape of the pollen grains varies among the species and among the grains within the same anther. The pollen grains are 3-colpate, prolate, with long and narrow colpi reaching the poles. The ornamentation of the exine varies from micro-reticulate to reticulate between the species. Pollen sterility/fertility was also calculated. The highest percentage of sterile pollen (73.76%) was calculated for Alyssum murale subsp. murale and the lowest (9.54%) for A. bertolonii subsp. bertolonii. All species are representatives of sect. Odontarrhena (C.A. Meyer) Koch well known as Ni-hyperaccumulators. Nickel and other elements present in pollen and stamen were studied by inductively coupled plasma-mass spectrometry. The stamen parts of all species were micromorphologically analyzed by scanning electron microscopy coupled to an energy-dispersive X-ray probe. Accumulation of Ni was detected in the stamens of all studied species and rarely in the pollen grains. The distribution patterns of Ni were similar among the species examined.     

Peculiarities of sexual reproduction inFagus crenata forests in relation to annual production of reproductive organs

Annual production rates of reproductive organs inFagus crenata forests in the lower area of the species' range were studied using 10 litter traps in 1980–1986. The production rates of dispersed pollen were estimated by multiplying the number of fallen male inflorescences per ha per year by the mean amount of pollen per inflorescence before anthesis. Large annual fluctuations in the production rates of male and female inflorescences were recognized, whereas their annual trends were synchronized with each other. Pollen production rates were within the range 1.0–6900 (mean: 1630)×10⁹ha⁻¹ yr⁻¹, the maximum/minimum ratio attaining 7000.F. crenata was the lowest producer of pollen among seven tree species studied: the number of pollen grains equivalent to a single ovule was in the range 6.0–14×10⁴. Furthermore, the mean dry weight of a single pollen grain (3.77×10⁻⁵mg) was higher than for wind-pollinated species. Three factors seemed to cause the low seed fertility ofF. crenata. The dry-matter production rate in the best seed year reached 3252 kg ha⁻¹ yr⁻¹, of which pollen accounted for 259 kg ha⁻¹ yr⁻¹. Unproductive years with less than 10% of the maximum production occurred four times in a 7-yr period. In such years there were fewer male and female inflorescences, and more fruit dropped as a result of insect damage. Lower nut dissemination would play an important role in suppressing any increase in nut predators, and fewer flowers would be produced to avoid wastage of photosynthates in a cool-temperate climate.     

Effects of environmental factors on pollen production in anemophilous woody species

The aim of this study was to estimate the amount of pollen produced by anemophilous woody taxa with allergenic properties and with considerable contribution in the concentration of pollen in the air of a Mediterranean city (Thessaloniki, Greece). The taxa selected are Corylus avellana, Cupressus sempervirens var. horizontalis and var. pyramidalis, Olea europaea and Platanus orientalis; each was studied in more than one sampling stations differing in elevation, direction or both. O. europaea produced the highest number of pollen grains per flower (1.3 × 10⁵ ± 0.1 × 10⁵) and P. orientalis the highest per inflorescence (3.3 × 10⁶ ± 0.2 × 10⁶). At the level of crown, pollen grains produced were of the order of 10⁹ per surface/volume unit for O. europaea and the two C. sempervirens varieties; for the other two taxa, they were of the order of 10⁶. Pollen production was lower at higher elevation and northern direction and depended on the size of the floral unit sampled (flower for O. europaea, inflorescence for all other species): the bigger the floral unit, the more pollen it contained. Our results and reports from other areas, where C. sempervirens and O. europaea grow, show that these two Mediterranean species produce comparable amounts of pollen at the levels of inflorescence or flower, respectively, wherever they occur.     

Intrusion of airborne pollen through open windows and doors

The importance of the transport of pollen by air movement into houses was evaluated using six to eight simultaneously collecting rotorod-type samplers, creating either a sampler line from outdoors to inside the room, or a sampler grid inside a room. The number of incoming pollen grains was highly dependent on the outdoor concentration. The highest concentrations inside (1–2 m distance) and outside (1 m) the room were 600 and 3,250 grains/m³, respectively, in the Betula pollen season and 1,980 and 5,080 grains/m³ in the Pinus season. The pollen concentration and the indoor/outdoor (I/O) ratio decreased as the distance from the ventilation opening increased. Inside the room at a distance of 1–2 m 28%, and at a distance of 3–5 m 12%, of the outside concentration was recorded. In the lower part of the opening the mean proportion was 63% and in the upper part of the opening it was 40%. Efficient ventilation with two open windows increased the I/O ratio and enabled the pollen to spread throughout the room. During the Pinus pollen season 3–35% of the outdoor concentration was simultaneously recorded at six locations inside the room with two open windows and only 0.1–3.6% with one open window. At the same point in the room the I/O ratio varied from <1 to 35%, depending on the sampling conditions. Only a minor effect on the I/O ratio was found between small and large ventilation windows and the door, although it was expected that more air and pollen grains would come indoors through a larger opening.     

Ultrastructure and Germination Percentage of Crocus biflorus Miller subsp. biflorus (Iridaceae) Pollen

Pollen of Crocus biflorus Miller subsp. biflorus from natural habitats of Tusculum (Frascati, near Rome, Italy) has been studied in order to compare its structure and physiology to pollen of other Crocus species belonging to the Crocus sativus group. Mature pollen grains are rounded, 60 μm in diameter, in-aperturate (but with surface incisions where exine is lacking). DAPI staining reveals a spindle-shaped generative nucleus which is intensely fluorescent, and vegetative nucleus which is less fluorescent, and is elongated with numerous lobes. At anthesis the pollen is bicellular, but about 2% of tricellular grains occur among the pollen grains released from the anthers as well as on both naturally or handpollinated stigmas. Pollen germination is low in vitro, but higher in vivo. The pollen tubes are of normal shape. An electron-dense surface coat is sometimes visible on the exine, which in many cases, is detached from the exine. The vegetative cytoplasm is very rich in glycolipid bodies surrounded by endoplasmic reticulum. The generative cell has a lobed cell wall and is surrounded by the vegetative nucleus.     

<Emphasis Type="Italic">Hirsutella proturicola</Emphasis> sp. nov. isolated from a proturan, <Emphasis Type="Italic">Baculentulus</Emphasis> densus (Protura,Hexapoda)

A new species of Hirsutella, H. proturicola, isolated from a subterranean proturan (Baculentulus densus; Protura, Hexapoda), is described and illustrated. Hirsutella proturicola is characterized by producing monoblastic phialides of 24–51.5 × 2.5–5 μm with a slightly roughened neck, fusiform and curved conidia of 9–18 × 2.5–4 μm that have a truncate base and a papillate projection often capped with sheath-like mucilage, and pluricellular, globose to subglobose chlamydospores of 21–48 × 21–41.5 μm. This species is morphologically and phylogenetically close to H. rostrata, an acaropathogenic species, but can be distinguished from the size of the phialides and the size and shape of the conidia.     

Palynological characters of Glycyrrhiza,Glycyrrhizopsis, and Meristotropis (Leguminosae), with special reference to their taxonomic significance

Abstract The pollen morphology of 11 species of the genus Glycyrrhiza L. with one from each of the genera Glycyrrhizopsis Boiss. & Bal. and Meristotropis Fisch. & C. A. Mey. was investigated by scanning electron microscopy. In pollen morphology, the main differences between Glycyrrhizopsis and Glycyrrhiza are: Glycyrrhizopsis—pollen grains 36.63 × 40.42 μm in size, oblate spheroidal in shape; and Glycyrrhiza—pollen grains 24.47–33.18 × 23.82–31.83 μm in size, prolate spheroidal in shape. Glycyrrhizopsis and Glycyrrhiza should be recognized as two distinct genera based on palynological and morphological characters. Meristotropis and Glycyrrhiza are similar in many important palynological and morphological characters, suggesting that the two should be merged. In Glycyrrhiza, two types of pollen grains, 3‐lobed‐circular or subtriangular in polar view, are found in different species, in accordance with morphological differences in the two groups, shedding light on the classification and evolution of the genus.     

Pollen morphology of the East Asiatic genus Chelonopsis (Lamioideae: Lamiaceae) and allied genera,with reference to taxonomic implications and potential pollination ecology

Pollen grains of 15 taxa of the genus Chelonopsis (14 spp. and 1 variety) from China and Japan and 6 species of the closely related genera Bostrychanthera (1 species) and Gomphostemma (5 species) were examined by light and scanning electron microscopy. Of these, the pollen morphology of 18 taxa was studied for the first time. Pollen grains were found to be tricolpate with polar lengths of 20.8–30.0 μm and equatorial widths of 17.5–27.3 μm. The basic shape of the pollen in most taxa is subprolate or prolate-spheroidal, but spheroidal, subprolate-spheroidal, oblate-spheroidal, and prolate-subprolate grains are also found in some species. The surface is generally reticulate or suprareticulate in Chelonopsis and granulate in Bostrychanthera. In comparison with those of Chelonopsis and Bostrychanthera, the pollen grain surfaces of Gomphostemma are more diverse. In Chelonopsis, pollen is taxonomically useful at the sectional level, and some grains provide enough characters for species delimitation. The potential pollination ecology of cellular hairs on the anthers of Chelonopsis and Bostrychanthera is also briefly discussed.     

Pollen morphology of some <Emphasis Type="Italic">Paronychia</Emphasis> species (Caryophyllaceae) from Turkey

The Pollen morphology of 13 taxa 11 of which are endemics belonging to Paronychia Miller (Caryophyllaceae) viz., P. agryloba, P. angorensis, P. arabica subsp. euphratica, P. carica, P. cataonica, P. chinonea, P. condensata, P. davisii, P. dudleyi, P. galatica, P. kurdica subsp. kurdica, P. kurdica subsp. montis-munzur and P. mughlaei from Turkey has been investigated by light (LM) and scanning electron microscopy (SEM). LM observations show that pollen grains are usually radially symetrical, isopolar, pantoporate, polygonal (6-gonal) or polygonal-spheroidal. Tectum is psilate or punctate. Tectal surface sparsely-densely spinulose. The numbers of pores are between 6 and 12. On the basis of pollen sizes, P. davisii was the biggest pollen type (23.45 μm) and P. kurdica subsp. kurdica (16.2 μm) was the smallest pollen types. According to exine sculpturing, pollen size and spinule numbers per 1 μm², three pollen types were distinguished.     

Pollen morphology and its systematic implications for the genera<Emphasis Type="Italic">Keiskea</Emphasis> miq. and<Emphasis Type="Italic">Collinsonia</Emphasis> L. (Elsholtzieae-Lamiaceae)

The pollen morphology of six species ofKeiskea and three representative taxa ofCollinsonia was studied in detail using LM, SEM, and TEM. In both genera, pollen grains are monad, hexa-colpate, and mostly medium in size [P = 28.0 to 37.0 μm, E = 24.3 to 30.7 μm (Keiskea); P = 30.0 to 45.0 μm, E = 26.0 to 39.0 μm (Collinsonia)]. Polar outlines are of circular or ellipsoid form. Shapes range from primarily oblate-spheroidal to prolate-spheroidal to subprolate, and rarely prolate in the equatorial view. Their exine, including the inline characters, are clearly distinct from each other:Keiskea, well-developed bi-reticulate, often forming large lumina by supratectal ridges, unbranched columellae, one-third to one-half of the total exine thickness; versusCollinsonia, mostly perforate without supratectal ridges or a faint/very weak bi-reticulate appearance without supratectal ridges, seemingly branched columellae, ca. two-thirds of the total exine thickness. As demonstrated by these current data, the pollen morphology of the two genera is well distinguished, easily supporting the separation ofKeiskea fromCollinsonia.     

Pollen diversity in Aquifoliales

Aquifoliales, as currently circumscribed, comprise five families and 20 genera, most of which have not been compared with regard to their pollen. Generic relationships within the order have not been fully resolved with molecular data, but pollen can provide a potential source of characters for future phylogenetic studies. To assess diversity in the order, pollen from 19 genera was examined with light and scanning electron microscopy. Pollen is typically tricolpate to triporate, although grains with one to nine pores were observed. Grains are small to medium, with a polar axis of 6–44 μm and an equatorial axis of 10–47 μm. Irregular pollen was recorded from nine genera. Exine patterning is diverse at the generic level and includes psilate, microechinate, striate to reticulate and clavate types, and is quite complex in some genera. All but four genera of Aquifoliales can be readily distinguished by their pollen, if heavy deposits of pollenkitt (present in 11 genera) are removed during and after acetolysis. Pollen from multiple taxa of Gomphandra, the second most diverse genus in the order, was surveyed to investigate species boundaries. Specimens of Gomphandra from continental Asia exhibited seven different pollen morphologies, suggesting that exine patterns may be useful for the recognition of species in that region. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 169–190.     

<Emphasis Type="Italic">Hieracium</Emphasis> subgen. <Emphasis Type="Italic">Pilosella</Emphasis>: pollen stainability in sexual,apomictic and sterile plants

Two pollen stainability tests (Alexander’s stain and acetocarmine) were used to detect differences in pollen viability of the sexual, apomictic and sterile plants of Hieracium subgen. Pilosella. In sexual taxa (Hieracium bauhini and H. densiflorum), the average stainability was 93.7–98.4%. Similarly high stainability (92.2–97.2%) was found in the apomictic Hieracium pilosellinum and in the majority of the apomictic populations (or plants) of the pentaploid and hexaploid H. bauhini. In some apomictic plants of Hieracium bauhini the average pollen stainability was 49.0–75.4%. The lowest pollen stainability was found in the sterile plants, i.e. the triploid H. pistoriense (33.6%) and the pentaploid H. brachiatum (29.6%).     

Pollen morphology of the genera Polygonum s. str. and Polygonella (Polygoneae: Polygonaceae)

The pollen of 30 taxa (27 species, one subspecies and two varieties) in two genera, viz Polygonum s. str. and Polygonella was investigated with LM and SEM, and some selected taxa with TEM. In all genera investigated the pollen is prolate to spheroidal, and the aperture is mostly tricolporate, rarely panto-hexacolporate (especially Polygonum section Polygonum). The exine sculpturing pattern is the most variable feature. Three types of exine can be recognized. Type 1 (Avicularia-Type, sensu Hedberg) - All species of section Polygonum and section Tephis share the smooth tectate exine with spinules, sometimes the surface is more or less rough (Polygonum afromontanum in section Tephis). Type 2 (Pseudomollia-Type, sensu Hong) - Pollen of Polygonum molliaeforme (section Pseudomollia) has the exine, which is verrucose on both poles and nearby the mesocolpium, and mostly psilate around the ectoaperture. Type 3 (Duravia-Type, sensu Hedberg) - Pollen grains of Polygonum section Duravia and Polygonella have the exine which is semitectate-reticulate at the mesocolpium and the poles, and rugulate/reticulate or sometimes foveolate with microspinules around the ectoapertures. The pollen grains in four taxa (viz Polygonum section Pseudomollia, P. section Duravia and genus Polygonella) have a well-marked dimorphism of the ektexine, which is considered to be a synapomorphic condition. The differences of pollen grain between the genus Polygonella and Polygonum section Duravia are almost non existent and clearly interrelated. It is therefore postulated that the similarity in pollen of both taxa is not the result of convergency, but is interpreted as a homology. It is noteworthy that the pollen of Polygonum molliaeforme (section Pseudomollia) appears as intermediate between the Avicularia-type and the Duravia-type, and is well supported the value of separated section for its own. Additionally, in TEM, some exine ultrastructures (e.g. columellae, foot layer, endexine) appear to be valuable characters for comparison between/among taxa. The systematic potentialities of the pollen data of the studied taxa at various systematic levels are also discussed.