Late Carboniferous palynostratigraphy of the Itararé Subgroup, northeastern Paraná Basin, Brazil

A new biozonation is proposed for the Late Carboniferous strata of the northeastern Paraná Basin (São Paulo and Paraná States), based on well-preserved palynological assemblages recovered from outcrops and core samples retrieved from the Itararé Subgroup. Assemblages include forty-nine species of trilete spores and twenty-five pollen species. The oldest biozone, the Ahrensisporites cristatus Interval Zone (AcZ), in the basal portion of the Itararé Subgroup, includes eleven exclusive spore species, and is assigned a Pennsylvanian (late Bashkirian to Kasimovian) age. The overlying proposed biozone, the Crucisaccites monoletus Interval Zone (CmZ), dated late Pennsylvanian (Kasimovian to Gzhelian), ranges approximately from the top of the lower portion to the middle portion of the Itararé Subgroup, bears only one exclusive species of pollen. Both zones are characterized by the dominance of trilete spores and monosaccate pollen grains, including also few taeniate pollen grains. Furthermore, the basal Protohaploxypinus goraiensis Subzone of the Vittatina costabilis Interval Zone (VcZ) is broadly recognized for the first time in the upper portion of the Itararé Subgroup in the northeastern Paraná Basin. This subzone is attributed to the Early Permian (Early Cisuralian), and is characterized by the dominance of monosaccate pollen grains, a significant increase of taeniate grains (mainly Protohaploxypinus spp.), apart from the appearance of polyplicate pollen (Vittatina spp.). Reference sections and the main characteristics of the two new zones (AcZ and CmZ) are presented, along with a preliminary palynological correlation and discussion on their ages.     

Pollen Organs and Seeds with Decussosporites Brenner from Lower Cretaceous Potomac Group Sediments of Eastern USA

Microsporangiate structures, Brenneria potomacensis gen. et sp. nov., containing pollen grains similar to dispersed Decussosporites are described from the Lower Cretaceous (Barremian or Early Aptian?) Potomac Group localities at Drewry's Bluff and Dutch Gap on the James River southeast of Richmond, Virginia. These fossils provide the first megafossil evidence of plants producing Decussosporites-type pollen and contribute important new information on the structure and possible systematic affinities of this unique Mesozoic gymnosperm. The microsporangiate structure is composed of an axis with helically arranged synangiate microsporangiate units, each unit consisting of two laterally fused sporangia borne on a short stalk. The pollen grains are very small, bisaccate, distinctly striate (taeniate) and TEM shows that they have partly infilled sacci (quasisaccate). These grains represent the youngest occurrence of saccate, striate pollen, which has not been recorded previously from sediments younger than the earliest Jurassic. Fossil seeds (Brennerispermum potomacensis gen. et sp. nov.) from the same localities as Brenneria contain Decussosporites pollen in the micropyle, and are believed to have been produced by the same plant species. The seeds are small and unitegmic with a distinct megaspore membrane. The occurrence of seeds adhering together in groups indicates that they were borne in aggregations. The microsporangiate structures of Brenneria show some similarity to those of the ginkgophytes (Ginkgoales and Czekanowskiales), but there are substantial differences in the structure of seeds and pollen. The Decussosporites pollen grains together with morphology of the reproductive organs support a closer relationship of the Brenneria-plant to previously described “Mesozoic pteridosperms”.     

Exine ultrastructure of in situ peltasperm pollen from the Rhaetian of Germany and its implications

Morphology and exine ultrastructure of pollen grains of Triassic peltasperms have been studied for the first time. Pollen grains of Antevsia zeilleri from the Rhaetian of Germany are of the Cycadopites-type and monosulcate; the sculpturing is the same in the apertural and non-apertural areas. The proximal exine includes a row of lacunae covered by a solid, thick tectum and underlined by a foot layer. Pillars are hanging from the tectum between the lacunae. The exine is thinning to a homogeneous layer in the apertural region. The latter is bordered by thicker alveolate areas of the exine, in places resembling a saccus-like ultrastructure. The endexine includes white-line-centred lamellae. The exine ultrastructure is compared with that of pollen of Permian peltasperms. Although pollen types ascribed to Permian peltasperms are completely different in their general morphology, a transformation can be hypothesized by ultrastructural data from Permian Vesicaspora into Triassic Cycadopites extracted from pollen sacs of Antevsia. Comparison with Cycadopites of non-peltaspermalean (Ginkgoalean, Cycadophyte) and unknown affinities has been accomplished. The exine ultrastructure is distinctive enough to differentiate among peltaspermalean, cycadalean and bennettitalean Cycadopites; some ultrastructural features are shared with pollen of modern Ginkgo biloba. More ultrastructural data are needed as well as numerous sections of pollen grains are necessary to reveal original unchanged ultrastructure.     

On Some Disaccate Pollen Grains of Permian to Middle Jurassic Age

The pollen of those organs producing disaccate grains of Permian to Middle Jurassic (Bajocian) age is reconsidered. The features used to distinguish disaccate pollen grains is discussed.     

Pollen Morphology of Asarum in China

The present paper describes the pollen morphology of 27 species, 4 varieties and 1 form of Asarum from China. The pollen grains were all examined under light microscope and scanning electron microscope. The apertures of pollen grains of Asarum are variable and so distinct as to allow the identification of individual subgenera and species. The exine ornamentation is compound and may be divided into two types: reticulate or cerebelloid under verrucae. The pollen grains of Subgen. Asarum and Subgen. Heterotropa are distinguishable, which supports the taxonomical subdivision based on the gross morphology. The differences in the pollen morphology between A. caulescens Maxim. and A. sieboldii Miq. in China and in Japan are discussed and some comparisons in the pollenmorphology between several species similar in the gross morphology are also made.     

中国紫草科厚壳树亚科的花粉形态及其系统学意义

为探讨厚壳树亚科在紫草科中的系统位置,用扫描电子显微镜研究了国产厚壳树亚科Ehretioideae的厚壳树属Ehretia、轮冠木属Rotula和基及树属 Carmona 3属12种植物的花粉形态,其扫描电镜资料属首次报道。从本文并结合文献报道的双柱紫草属 Coldenia的花粉资料,可得知该亚科花粉为长球形 、近球形,稀球形,赤道部位具有不同程度的膨大;萌发孔类型为三孔沟和三拟假沟二者交替排列,稀具三孔;外壁表面具微弱的小穿孔,稀光滑或皱波状纹饰。厚壳树亚科Ehretioideae与破布木亚科     

Evolution of pollination system and characters of stigmas in Najadales

Diverse ways of pollination, including aerial, epihydrophilous and hypohydrophilous ones occur in the Najadales. Although the knowledge of pollination biology in this order has been largely accumulated in recent years, most researchers ignored the role of stigmas in the pollination process. Based on the previous works, we supplemented observations on stigmatic characters and pollination mechanism in nine species from four families. The flowers of Aponogeton lakhonensis ( Aponogetonaceae ), Triglochin palustre ( Juncaginaceae), Potamogeton crispus, P. distinctus, P. gramineus, P. pectinatus, P. perfoliatus, P. pusillus (Potamogetonaceae), are all found to open above or on water surface. Stigmas in these species have a large surface area. Correspondingly, the pollen grains are all found to be globular. Of the eight species, except for P. pectinatus and P. pusillus, the remaining six obviously expose their stigmas out of the perianth. Another species , Najas marina (Najadaceae), has filiform stigmas and ellipsoidal pollen grains which can germinate in water before being transferred onto stigmas in natural conditions. Pollination takes place in this species strictly under water. The characters of pollen and stigmas could be divided into two types, and the pollination system is of two kinds of mechanisms of stigmas capturing pollen in the Najadales. The species with globular pollen grains have wide, large stigmas while those producing filiform or precocious pollen grains, which are likely to be captured by stigmas during the pollen dispersal by water currents, normally have filiform stigmas. It is inferred that various water stresses might have resulted in the diversification of pollinationsystem in the Najadales.     

茨藻目植物柱头特征与传粉系统的演化

茨藻目包含有风媒、水表水媒和水下传粉的多种传粉方式。在前人工作的基础上,补充了4科9 种植物的柱头特征和传粉机制的观察。该目花粉和柱头特征可分为两类,传粉系统表现出两种不同的柱头捕获花粉的机制。花粉为球形的种与其宽大的柱头相配;而那些花粉演化为丝状或花粉在水中具先期萌发能力的种,其花粉易被其丝状的柱头所捕获。此外,还推测了导致这个类群传粉系统分化的可能原因。     

Localization and release of allergens from tapetum and pollen grains ofBetula pendula

Summary Although intact pollen grains are assumed to be the primary carrier of pollen allergens, specific immunoreactive components have been found in other aerosol fractions, e.g., starch grains and remains of tapetal cells Cryo-scanning-electron-microscopy results demonstrate the presence of a clear network of strands connecting the tapetum with the microspores. The distribution of protein in tapetal orbicules, pollen wall, and pollen cytoplasm was tested by histochemical stains for light microscopy and transmission electron microscopy. The protein is mainly localized at the apertures and starch grains in the cytoplasm of pollen and in the core and on the surface of tapetal orbicules. Monoclonal antibodies Bv-10, BIP3, and BIP4 have been used to locate the cellular sites of pollen and tapetal allergens inBetula pendula (syn.B. verrucosa). The application of rapid-freeze fixation prevented relocation of allergens from their native sites. The allergens are predominantly found in the starch grains and to lesser extent in the exine. We also tested interactions between mature birch pollen and human fluids: saliva, nostrils fluid, and eyes solution. The aim was to mimic more closely the in vivo situation during allergenic response. In all cases we observed several pollen grains that were burst and had released their cytoplasmic contents. In the nose the allergens are released from the pollen within minutes. In rhinitis, nasal pH is increased from the normal pH 6.0 to 8.0. When we used nasal fluid at pH 8.0, the number of ruptured pollen grains increased. The mechanism that might induce formation of small allergen-bearing particles from living plant cells is discussed.     

Banksia pollen in the diet of Australian mammals

Mammals are frequent visitors to flowers in some Australian plant communities Nectar is usually considered to be the food sought, because pollen is thought to be of low digestibility This study compared the abilities of four non-flying mammal species to extract the protoplasts from Banksia pollen grains and quantified the amount of pollen in the diets of the species over 16 months All four species were capable of extracting the protoplast from a large proportion of the pollen grains that they ingested the mean percentage of empty Banksia pollen grains in the faeces ranged from 37% to 66% Banksia pollen was a major component in the faecal samples from two species, Cercartetus nanus and Petaurus breviceps , between March and October It occasionally comprised a large proportion of Amechmus stuartti faeces but was rare in the faeces of Rattus fuscipes Other major components of faeces included invertebrates and plant material other than pollen and fungal spores As the four mammal species tested were all from separate families and all capable of extracting the protoplast from a large proportion of the pollen grains, it is concluded that the extraction of pollen protoplasts by mammals may be widespread and may require no special adaptations     

猕猴桃属花粉形态及其系统学意义

由于天然种间杂交,猕猴桃属Actinidia Lindl.的分类存在着组间界限不清、近缘种之间很难区分的问题。本文试图通过对该属不同组、系的植物花粉及种间杂交后代花粉的扫描电镜观察,探讨该属物种的系统学关系。在扫描电镜下观察了猕猴桃属植物21种、 6变种和4个不同种间杂交F1代植株的花粉,描述了它们的花粉形态,并根据花粉形态特征建立了相应的检索表。研究结果表明：（1）猕猴桃属的花粉形状主要以长球形至近球形为主,变异较小,而花粉粒大小和外壁纹饰的种间差异较大。（2）多数迁地保护物种的花粉粒以三孔沟为主,不同于以前报道的以三拟孔沟为主,原因可能是花粉样本采集地的环境不一样,以及野外的广泛杂交造成的。（3）种间杂交后代花粉空瘪,无授粉能力,是由于所采用亲本植株染色体的倍性不同,后代不能产生正常花粉所致。（4）人工选育雄株花粉外壁纹饰较野生雄株花粉的精细,这种花粉外壁纹饰变小的特征可能有利于雌雄异株植物的授粉受精。这一现象值得进一步探讨。（5）雄株花粉大小与其雌株果实大小之间有一定相关性,这一现象有助于杂交后代的早期筛选。     

The contribution of long-distance transport to the presence of <Emphasis Type="Italic">Ambrosia</Emphasis> pollen in central northern Italy

Ragweed is an allergenic weed of public health concern in several European countries. In Italy ragweed occurs prevalently in north-north-eastern regions, where sensitization is increasing. Because of the small diameter of pollen grains, ragweed pollen is often involved in episodes of long-range transport, as already shown in central Italy. The objective of this study was to evaluate the extent of such transport by comparing pollen and meteorological data for two northern Italian cities (Parma and Mantova) with data from Pistoia and Florence in central Italy. In 2002 and 2004 peaks in ragweed pollen levels were detected in these four cities on the same day, and concentrations of the grains were above clinical thresholds. Weather-map analysis and computation of back-trajectories showed that air masses from eastern Europe might carry ragweed pollen to a wide area of central and northern Italy. These findings suggest that episodes of long-range transport of ragweed pollen could be clinically relevant, resulting in sensitization of a large number of people. The results might provide a basis for monitoring and forecasting periods of long-distance transport with the objective of reducing their effects on allergic patients.     

Pollen morphology of the Schisandraceae and its systematic significance

Pollen morphology of 91 samples, representing 23 species, 6 varieties and 1 form of the Schisandraceae, was examined under light microscope (LM) and scanning electron microscope (SEM). Palynological data of 5 species, 4 varieties and 1 form are reported for the first time. The pollen grains are monads, heteropolar, radiosymmetric and oblate to peroblate in shape. Arrangement of their colpi is unique in angiosperms. The pollen grains can be divided into two types according to the number of their clopi: the tricolpate pollen type and the hexacolpate pollen type. The exine sculpturing is reticulate. The size of luminae and the breadth of muri are correlated with the floral morphology of the hisandraceae to a certain extent. Our results do not support the division of the pollen grains of the Schisandraceae into 4 types according to the size of inae as proposed by Praglowski. There is also still room of discussion about his conclusion that the pole where the three longer colpi converge is the distal pole. The evolutionary trends of the pollen grains of the Schisandraceae seem to be from fewer to more in the number of colpi, and from smaller to larger in the size of luminae. The view that Kadsura is more primitive than Schisnadra is not supported by palynological data; on the contrary, Kadsura seems to be more advanced than Schisandra at the general level of evolution. The two genera may be closely related, and might have originated from a common ancestor and then evolved parallelly along two different routes.     

Dispersal of fungi spores by non‐specialized flower‐visiting birds

Birds are important biotic dispersers of a wide range of propagules. Fungi spores are mainly dispersed by wind. Nevertheless there are several animals known to disperse fungi spores, which might be particularly important if spores are delivered to particularly favourable sites i.e. directed dispersal. This may be especially important for fungi that require specific microsites such as flowers. We sampled birds for the presence of fungi spores and pollen grains during one year at two forest sites in central Portugal. We found that out of the 894 birds sampled, 131 individuals from 11 species carried spores from at least 6 morphological types, mainly during winter. The great majority of birds found to carry fungi spores was also found to carry pollen grains, suggesting that they were feeding on flowers which are the main origin of the spores. This co‐dispersion of pollen and fungi spores suggest that the latter are not randomly dispersed on the environment, but are likely to have an increased probability of being deposited on flowers propitious to fungi development. Our results suggest that directed dispersal of fungi by flower‐visiting birds might by a common and under‐appreciated phenomenon with potentially important ecological, biogeographic and even economic outcomes.     

Studies in Montia L. and Claytonia L. and Allied Genera

The pollen morphology of several genera in Portulacaceae is described. Particular attention has been paid to the genera of the subfamily Montioideae, as a stage of continued monographical studies. Among genera especially dealt with are Claytonia, Montia, Crunocallis, Naiocrene, Neopaxia, Mona, Maxia, Limnalsine, and Montiastrum. In the taxonomical treatment of these genera the pollen morphology has proved to afford many important additional characters.

The pollen grains of Claytonia are distinguished from those of the remainder in being 3-colpate. The grains of the Claytonia-type have many similarities with those of Lewisia, a genus of the subfamily Portulacoideae. The other genera of Montioideae have pantocolpate pollen grains. Among these genera several different pollen types are distinguished, chiefly with regard to the sexine structures and the aperture membranes. The Montiastrum-type is especially interesting, with tholate grains, a particular pollen type not met with in any other genus in the family. The pollen morphology of some genera in the Portulacoideae is also treated. In some species in Calandrina and Talinum pantotreme pollen grains are observed with apertures transitional between pori and colpi. The apertures of the pantotreme grains are arranged in characteristic patterns.

Particular attention has been given to the variation of the pollen morphological characters. This variation has been examined with regard to the differences between different populations of the same species as well as between different species. The greatest variation has been observed in the shape and size of the grains. The structure and sculpture and thickness of the sexine and the aperture membranes are less variable. Some polyploid taxa are connected with the occurrence of pollen grains with divergent and varying aperture numbers.

In a survey of the genera the taxonomical results of the investigation are presented with particular regard to the pollen morphology. The new genus, Maxia Ö. Nilss., is described. One new species, Montia clara Ö. Nilss., is described and some new combinations are made.

Pollen morphological diagnoses are given for 46 different taxa. The aperture conditions for 96 different species are presented.     

五味子科植物花形态及其系统学意义

用光镜和扫描电镜观察了五味子科Ｓｃｈｉｓａｎｄｒａｃｅａｅ２３种、６变种和１变型的９１份花粉的形态。其中５ 、４变种和１变型的花粉形态为首次报道。该科花粉为单花粉,异极,辐射对称,扁球形至超扁球形,其萌发沟的排列格局在被子植物中是独一无二的。若按萌发沟的数目划分,该科花粉可分为３沟型和６沟型两个类型。外壁为网状纹饰,网眼的大小和网脊的宽度与花的形态有一定相关性。研究结果不支持Ｐｒａｇｌｏｗｓｋｉ对     

Chromosomes from Herbarium Sheets of Impatiens

In northwestern Himalayan species of Impatiens, the pollen grains at shedding possess a crescent shaped generative nucleus in prometaphase from which the chromosome number is easily determined. The fresh or fixed pollen grains are studied by the usual aceto-carmine squash method. The generative nucleus generally remains in the same state in pollen of the herbarium specimens. Anthers from such material are soaked overnight in a saturated solution of iron acetate in 45% acetic acid, rinsed and squashed in dilute aceto-carmine. Preparations are heated several times to boiling. Reliable counts of chromosomes have been made from such slides.     

Sexual dimorphism in pollen grain size in cryptically dioecious Thalictrum macrostylum

While several plant species are initially described as androdioecious, upon more thorough investigation, many of these are found to be cryptically dioecious with functionally male flowers and perfect flowers that produce inaperturate pollen or are otherwise functionally female on separate plants. The change in function of pollen produced by perfect flowers opens up the possibility for the evolution of sexual dimorphism in pollen grain size. We found that Thalictrum macrostylum (Ranunculaceae) is cryptically dioecious, and produces apparently inaperturate pollen in perfect flowers. In four field sites throughout North Carolina, inaperturate grains are larger than grains from staminate flowers and also show a greater variance in size. We also found substantial variation in pollen grain size among plants. The sites with lower soil nutrient content also had smaller pollen grains of both types, although local adaptation or genetic drift may also be causing among-site variation.     

High-throughput procedure for single pollen grain collection and polymerase chain reaction in plants

Single pollen grain polymerase chain reaction （PCR） has succeeded in several species, however only limited numbers of pollen grains were involved due to difficulties in pollen isolation and lysis. This has limited its application in genetic analysis and mapping studies in plants. A high-throughput （HT） procedure for collecting and detecting genetic variation in a large number of individual pollen grains by PCR is reported. The HT procedure involved the collection of individual pollen grains by a pair of special forceps and the lysis of pollen grains in a heated alkali/detergent solution followed by neutralization with a tris-ethylenediamine tetraacetic acid （TE） buffer. These resulting template solutions yielded PCR reactions involving the 5S ribosomal RNA intergenic spacers, randomly amplified polymorphic DNA, and simple sequence repeats markers. Using this procedure, one person with experience could collect and process up to 288 single pollen grain PCR reactions per day. The method worked well on sugarcane, corn, Miscanthus spp., snap bean, sorghum, and tomato. The ability to collect and conduct PCR on individual pollen grains on a large scale offers a new approach to genetic analyses and mapping studies in an easily controllable environment with a considerable cost reduction. The method will also significantly benefit studies in species that are difficult subjects for classical genetic research.