Shape Of Pollen Grains Research Articles

Pollen morphology of four species of Jatropha (Euphorbiaceae), including toxic varieties, in Northwestern Mexico

Jatropha curcas is a native Mexican plant, distributed in the forests of coastal regions; it has shown potential for the production of biofuel, and its raw protein can be used as animal feed. Nevertheless, its current varieties have low yield and production variability, as it is in domestication period. The knowledge of the pollen grains is fundamental for studies of Jatropha reproductive biology and breeding for genetic improvement to generate new hybrids and improve fruit and seed yield. This study compared pollen morphology of four Jatropha species, which include two varieties of J. curcas (one toxic from India and one non-toxic from Mexico), and two varieties of wild J. cinerea (Sinaloa and Baja California Sur); additionally, pollen was collected from wild J. platyphylla (Sinaloa) and J. vernicosa (Baja California Sur) to characterize them palynologically. We used a scanning electron microscope to describe the size and shape of pollen grains. Pollen grains were observed spheroidal. The diameter of the varieties of toxic and non-toxic J. curcas and that of J. platyphylla were 58 ± 2.3, 54 ± 1.7, and 51 ± 2.4 µm, respectively; the number of clavae was 84 ± 10, 108 ± 15, and 180 ± 15.5, respectively. Pollen grains of J. cinerea (Sinaloa) had a diameter of 50 ± 1.7 µm and 220 ± 14 clavae by area; J. cinerea (Baja California Sur) had a diameter of 45 ± 1.9 µm and 195 ± 14.7 clavae. Pollen grains of J. vernicosa had a diameter of 46 ± 2.1 µm and 231 ± 25.6 clavae. The ornamentation of the exine showed clava with capita gemma shaped for varieties of J. curcas species and clavum shaped for J. platyphylla, J. cinerea and J. vernicosa species. The studied varieties have a cross-linked endexine and ectexine intectate. Luminal bacules were observed in the reticular space of J. curcas varieties while none were present in the varieties of J. cinerea, J. platyphylla, and J. vernicosa.

Palynomorphological Data of Some Species of the Genus Achillea

The article includes the palynomorphological study of some species of the genus Achillea in Albania. In this article submitted comparative features of the species: Achillea abrotanoides, Achillea ageratifolia, Achillea clavennae, Achillea chrysocoma dhe Achillea millefolium. The material for the study was obtained in National Herbarium in Tirana. For the study of palynomorphological features are analyzed 31 pollen grains from each species. The treatment of material is made with acetolysis method and basic fuchsine. The fixing of pollen grains is made with glycerin gelatin. The study and photos of pollen grains are realized with light microscope with 1000x power. Between the plant species included in the study are differences and similarities regarding the palynological features such as: dimension of pollen grain, thickness of exine, length of spines, width of spines. The pollen grains of plants above are tricolporate. The shape of pollen grains by the outline appears spheroidal or prolate spheroidal. The exine appears thick and has two-layers. The sculpture of exine is echinate. DOI: 10.5901/ajis.2016.v5n3s1p74

Systematic Importance of Pollen Morphology of Some Plants of (Lamiaceae)

<p>Pollen morphology of seven taxa belonging to Lamiaceae and common used as medicinal plants were examined by light (LM) and scanning electron microscopy (SEM).<em> Thymus vulgaris</em> L.<em>, Mentha longifolia</em> (<a title="Carolus Linnaeus" href="https://en.wikipedia.org/wiki/Carolus_Linnaeus">L.</a>) <a title="William Hudson (botanist)" href="https://en.wikipedia.org/wiki/William_Hudson_(botanist)">Huds.</a> Mentha<em> spicata L.</em>, <em>Ocimum basillicium L.</em>, <em>Salvia elegans </em>Vahl<em>, Salvia farinace</em><em>a</em> Benth, and<em> Salvia splendens</em> Sellow ex Roem. and Schult. Pollen morphological characteristics are provided for these taxa. Among the studied taxa, <em>Mentha longifolia</em> has the smallest pollen grains, and <em>Ocimum basillicium</em> possesses the largest ones. The main shape of pollen grains in the most taxa suboblate, oblate – spheroidal or prolate–spheroidal. However subprolate are recorded for <em>Salvia elegans</em>. The grains are hexacolpate in all taxa, but in <em>S.</em><strong><em> </em></strong><em>farinacea</em> octacolpate pollen was found. Three distinct exine sculpturing exist, reticulate–perforate the common type, also reticulate, granulate and bi-reticulate. However, the fine details are characteristic to differentiate between the pollen species. Exine is microreticulate in case of <em>S</em>. <em>elegans</em> and <em>S.</em><strong><em> </em></strong><em>farinacea</em>, but reticulate-foveolate in case of S<em>. splendens</em>. As well as, the presence of holes on colpus membrane ornamentation can be used as a taxonomic tool for sectional division between. <em>S. </em><em>elegans</em> from <em>S</em><em>. splendens</em> is clearly distinct from the other taxa examined by its characteristic pollen morphology. </p>

Investigation of pollen morphological characteristics in some quince (Cydonia oblonga Mill.) cultivars

Morphological characterization of pollen grains is very important in the identification of individual species and cultivars of fruit trees, including quince. As material for these studies, the pollen of eight quince cultivars, Leskovacka, Vranjska, Morava, Pazardzijska, Hemus, Asenica, Portugal, and Triumph was used. During the 3-year study period (2010-2012), using scanning electron microscopy (SEM), the following characteristics were investigated: the size and shape of pollen grains (length, width, and length-to-width ratio), colpus length, colpus width, mesocolpium width, and characteristics of exine pattern [number of ridges per area (100 μm2) at the equatorial region of exine, ridge width, and furrow width]. The tested quince cultivars differed significantly in terms of morphological characteristics of pollen. The exceptions were colpus and mesocolpium width, as well as the ridge and furrow width on the exine, which showed no statistically significant difference. Pollen grains of quince are characterized by great length (over 53 μm). The shape of pollen grains varied from prolate (Leskovacka, Vranjska, Morava, Hemus, Asenica, and Triumph) to perprolate (Pazardzijska and Portugal). The exine pattern of all cultivars was striate with longitudinal ridges, which were more parallel in cultivars Vranjska, Hemus, Portugal, and Triumph and less parallel in cultivars Leskovacka, Morava, Pazardzijska, and Asenica. Three groups of similar cultivars are separated on the basis of hierarchical cluster analysis results. Some pollen morphological characteristics, such as the size and shape of pollen grains and colpus length, can be used in the identification of quince cultivars.

The Palynomorphological Characteristics of Galatella Albanica Degen (Aster Albanicus Degen ) (Asteraceae)

Galatella albanica Degen the synonym Aster albanicus Degen takes part in the tribe Astereae, subfamily Asteroideae (Asteraceae). It is an endemic specie of our country, Albania,but we can find them even in Kosove and in the south of Serbia. In Albania we find Galatella albanica Degen in dry and rocky places and a few in sandy places which have humidity (Durres - Karavasta). This plant is studied even by the previous authors with the material taken from the rocky areas of Librazhdi and Shkopeti. The material for this study is taken fresh from the sandy places in the wood of Divjaka because of the aim of this study is to see if the ecologic factor affects on the pollen grains of this plant. According to the results of this study, the pollen grains of Galatella albanica Degen are tricolporate. In ecuatorial view the shape of pollen grains is elliptic to circular, while in polar view the shape is circular to triangular. The exine has an echinate sculpture and it has two- layer. DOI: 10.5901/ajis.2015.v4n2s2p196

Palynological characterization of species of Sesamum (Pedaliaceae) from Kerala: a systematic approach

The study deals with the pollen morphological characterization of thirty-seven accessions under six species of Sesamum, including the wild and cultivated taxa, collected from the state of Kerala. The assessment of species relationship of the taxa forms the pivotal aim of the investigation. The study displayed the significance of palynological characters such as aperture type, size and shape of pollen grains and exine ornamentation in the delimitation of the taxa at inter- and intra-specific levels. The species exhibited uniformity in their aperture morphoform (stephanocolpate), though they differed in the number of apertures. Wide variations observed in the exine ornamentation such as reticulum cristatum with gemmate (S. indicum), baculate (S. radiatum, S. prostratum), verrucate (S.malabaricum), areolate (S. laciniatum) and gemmate with clavate (S. alatum) suggested the utility of the character in the systematics of the genus. Inter-specific variation noticed in the size and shape of the pollen grains ranged from medium (S. laciniatum) to large (S. radiatum and S. malabaricum) and suboblate to prolate, respectively. The study explained the evolutionary relationship of the taxa based on pollen morphology. A taxonomic key is also prepared and presented based on the characters analysed.

Pollen morphology of Androsace (Primulaceae) and its systematic implications

AbstractA close relationship between Androsace and related genera (Douglasia, Vitaliana, and Pomatosace) has long been recognized. Recent molecular studies have provided abundant evidence that Douglasia, Vitaliana, and Pomatosace are nested within Androsace and together constitute the monophyletic “Androsace group”. We investigated the pollen morphology of 80 taxa representing all sections of Androsace s.s. as traditionally construed, as well as Douglasia, Vitaliana, and Pomatosace, to see whether they are congruent with phylogenetic relationships. We uncovered subtle variation in pollen morphology within the group. The shape of pollen grains ranges from spheroidal to perprolate. Pollen size ranges from 9.37 µm in Androsace sect. Samuelia to 20.68 µm in Douglasia. Exine ornamentation includes microreticulate, microechinate, perforate, and rugulate types. The polar view varies from circular, triangular and planaperturate, to triangular and angulaperturate. Various pollen morphological characters support the monophyly of major clades, including /Septentrionalis, /Pomatosace, /Orthocaulon, and /Megista, which were recognized previously based on molecular evidence.

Pollen morphology of <i>Verbascum</i> L. (Scrophulariaceae) in Northern and Central Iraq

The present study highlights the taxonomic values of the pollen features of 20 species of Verbascum L. in Iraq. The pollen grains were acetolysed and observed under Light and Electron microscopes. Our results showed that the pollen grains of these species are usually radially symmetrical, isopolar, tricolporate and display reticulate sculpturing. The variations were found in shape, size, and exine thickness. Most of the species are subprolate, prolate spheroidal, and prolate, whereas oblate spheroidal pollens were found only in V. thapsus. The pollen size among the species studied ranges from 16.2-32.5 µm. The majority of species are medium sized except V. agrimoniifolium and V. oreophilum that are small sized, and four species i.e. V. palmyrense, V. sinuatum, V. songaricum, and V. thapsus having both small and medium sized pollen grains. Moreover, the result showed that the exine thickness ranges from 0.87-4.75 µm, but this value can overlap between some species. Therefore, only the shape of pollen grains could be used to classify these species into groups.DOI: http://dx.doi.org/10.3329/bjpt.v21i2.21355Bangladesh J. Plant Taxon. 21(2): 159-165, 2014 (December)

Some evidence for infrageneric classification in Ziziphora L. (Lamiaceae:Mentheae)

The genus Ziziphora L. (Lamiaceae) consists of annual herbs, except Ziziphora clinopodioides, and is represented by six taxa in the flora of Turkey: Z. clinopodioides, Z. capitata, Z. persica, Z. tenuior, Z. taurica subsp. taurica and Z. taurica subsp. cleonioides. They are strong aromatic herbs and important medicinal plants. This study has been conducted to determine the palynological and karyological features of these taxa. The pollen morphology and exine structure of Ziziphora species were investigated by light microscope and scanning electron microscope. Pollen grains were determined as hexacolpate, medium in size and a circular or elliptic amb. The shape of pollen grains varies from oblate to prolate spheroidal. Ornamentation types of pollen grains are bireticulate, microreticulate or perforate. Somatic chromosome number has been determined and counted as 2n = 16, 18. Results indicate that the pollen characters and chromosome numbers of the genus are valuable for taxonomic applications and may be useful for infrageneric classification.

Pollen character IstIcs In some Diospyros sPecIes

Aim of the work was to study the general characteristics and essential morphological traits of pollen grains viz the size, shape of pollen grains and number, form and position of apertures in Diospyros kaki L.f., D. virginiana L., D. lotus L. species and interspecies hybrid of D. virginiana × D. kaki. Significant differences were detected among the tested species and the interspecific hybrid as well as between individual genotypes of D. lotus, especially in the equatorial axis.

On flowering patterns of alien species: 2. Robinia pseudoacacia, R. × ambigua, and R. neomexicana

A comparative study of the structure of the flower in three species of Robinia L., R. pseudoacacia, R. × ambigua, and R. neomexicana, was carried out. The widely naturalized R. pseudoacacia, as compared to the two other species, has the smallest sizes of flower organs at all stages of development. Qualitative traits that describe each phase of the flower development were identified. A set of microscopic morphological traits of the flower (both quantitative and qualitative) was analyzed. Additional taxonomic traits were identified: shape of anthers, size and shape of pollen grains, and the extent of pollen fertility.

Pollen morphology of the genusPotentilla(Rosaceae) in Iran

The pollen morphology of 28 species of the genus Potentilla (Rosaceae) and four related genera from Iran was examined using light (LM) and scanning electron microscopy (SEM). The pollen grains are radially symmetrical, isopolar to subisopolar, trizonocolpate and colporate. The shape of pollen grains in all the studied taxa varies from prolate-spheroidal to subprolate and prolate. The outline of the pollen grains is elliptical in equatorial view and triangular-circular in polar view. The size of the pollen grains is small to medium. Our results showed two main types of exine sculpturing. Among the studied pollen grain characters, shape and size are helpful evidences for separating different sections, while the exine sculpturing type provides limited taxonomic value.

Does climate affect pollen morphology? Optimal size and shape of pollen grains under various desiccation intensity

Seed production is likely constrained by pollen limitation and the viability of pollen grains decreases rapidly in time due to water evaporation. Any decrease in the surface-to-volume ratio, through increase in size or change in shape of a grain, reduces the rate of water loss. However, grain size trade-offs with the number of grains that can be produced by a plant. Here, we tested the hypothesis that under higher desiccation stress pollen grains become larger and more spherical. We analyzed data on the pollen morphology of eight Rosaceae species and the desiccation intensity based on temperature, potential evapotranspiration and altitude. To explain the mechanisms underlying our results, we present a model that optimizes the size and shape of pollen grains under different conditions. We report that pollen grains under more intense desiccation stress during flowering periods tend to be larger but do not change shape. This conclusion is consistent with the results of a theoretical model presented here. Our report fills a gap in our knowledge about a fundamental process in plant reproduction. We also discuss the significance of our results in light of current palynological and ecological problems (e.g., global climate change).

Preliminary Studies on Observation of Pollen Morphology by Scanning Electron Microscope for Forensic Discrimination

The use of a scanning electron microscope (SEM) for forensic pollen analysis was examined as a preliminary study on pollen samples collected from twenty-seven species in general public areas. Pollen samples were air-dried and coated with gold without any pre-treatment which were conventionally performed to remove oil and dewatering. The shapes of pollen grains were observed at magnification of between ×1500 and ×3000, and sculptures were at ×15000. Samples were grouped into three by aperture types, and subdivided by sculptures as the result of observations. Pollens of different families in the same subdivision were distinguishable from the careful observations of details. Pollens of the same genera were grouped in the same subdivisions. It was clarified that use of SEM without any pre-treatment has a high potential for the forensic discrimination of pollen as evidence.

Pollen Morphology of Parnassia L. (Parnassiaceae) and Its Systematic Implications

The pollen morphology of 28 species of Parnassia L. was investigated with light microscopy and scanning electron microscopy (SEM). The shape of pollen grains in this genus varies from subspheroidal to prolate in equatorial view and is three-lobed circular in the polar view. Pollen grains are usually radially symmetrical, isopolar, tricolporate or syntricolporate, with reticulate sculpture. The pollen characteristics among species are fairly similar to each other. Morphological information regarding the pollen grains shows that Parnassia is a natural genus. Based on exine ornamentation observed under SEM, three types of pollen grains were recognized: (i) type I, with foveolate-reticulate sculpture; (ii) type II, with a finely reticulate sculpture; and (iii) type III, with a coarsely reticulate sculpture. Most sections of this genus have one type of sculpture of pollen morphology, but Sect. Nectarotrilobos has three types of sculpture and Sect. Saxifragastrum has two types of sculpture. All three types of sculpture can be found in Southwest China, with species with the longest (Parnassia delavayi Franch.) and shortest (Parnassiafaberi Oliv.) colpi, implying that Southwest China is the center of diversification of the genus.

Airborne pollen texture discrimination using wavelet transforms in combination with cooccurrence matrices

In the recent years, image processing and pattern recognition techniques have been applied to develop intelligent systems for both of fresh and fossil pollen grains discrimination. In this paper, we aim at the texture identification of pollen surface images. A method of texture description using wavelet transforms in combination with cooccurrence matrices is presented, and a neural network is used to classify the extracted image features. In this combined method, through wavelet decomposition and reconstruction, an approximation image and a new details image are generated for the input image. The surface texture of pollen grains is characterised by using a rotational invariant feature set, which is formed from the joint distribution of the grey level and the details information. In order to form effective feature vectors, the moment invariants also were employed to describe the surface shape of pollen grains. Both the back-propagation (BP) and the learning vector quantisation (LVQ) networks were used for classification of the resulting feature vectors. In experiments with sixteen types of airborne pollen grains, more than 91% pollen images are correctly classified using both the methods.

Bend it like pollen

An artist who has had to learn how to use a scanning electron microscope to help create his images now has some of his works on public show in London. As part of Kew Gardens' Go Wild festival, Rob Kessler has on display several images inspired by the remarkable twists and turns in the shape of pollen grains from different plant species collected by the artist from specimens growing in the gardens' cornfield last summer. Kessler was awarded a three-year grant to work with Madeline Harley at the Micromorphology Unit at Kew. The remarkable shapes of pollen grains reveal important diagnostic features of plants used by scientists. They provide valuable evidence about the evolution of plants and relationships between species. Kessler has produced these images to highlight remarkable structures not usually visible to the naked eye. Pollen studies also contribute to other areas of research including, for example, commercial pollination in crop production and the identification of plant species used in medicines. The study of pollen is also valuable to other activities including honey manufacture, forensics, the oil industry and bee keeping. For his artwork, Kessler captured images with the scanning electron microscope and manipulated them using computer graphics. The results are bold, colourful images screenprinted onto transparent banners strung between trees at Kew, making a powerful metaphor for some of the pollen grains blowing around for real.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Morphologie pollinique des Cupressaceae de l'est du Canada et du nord-est des États-Unis appliquée à l'étude des sédiments quaternaires

The pollen morphology of seven species, varieties and forms of Cupressaceae from eastern Canada and northeastern United States was studied by light microscopy, following acetolysis, to improve the identification of these taxa in Quaternary fossil sediments. Taxodium distichum (Taxodiaceae), which is also present in the study area, was included for comparison. Four pollen types were defined: Juniperus communis – Thuja occidentalis, Chamaecyparis thyoides, Juniperus horizontalis – Juniperus virginiana, and Taxodium distichum. Five shapes of pollen grains exist: whole, slightly split, opened in a "V" shape, spindlelike, or split in halves. All shapes are found in all species, in varying proportions, and represent different stages of hydration in Cupressaceae pollen type. The absence or presence of these shapes cannot be used as an identification criterion for the different species. A pollen identification key, applicable to fossil sediments and combining characters based on shape, size and other morphological features of acetolysed grains, is proposed and allows to differentiate all the species from one another, with the exception of Juniperus horizontalis and Juniperus virginiana.

The effects of pre-treatment and the embedding media on the shape of pollen grains

Observations were made on the distortion in pollen-grain shape produced by mounting media of different viscosities. The extent of collapse of acetolysed Carex, Picea and Larix pollen grains was judged to depend upon pollen-morphological, chemical and physical factors acting together on the pollen wall during the pre-treatment and mounting for light microscopy. It was observed that pollen grains remained generally more spheroidal in fluid media of low viscosity than in fluid media of high viscosity or solid media.

Palynological studies in some non-commercial citrus varieties

1. The shape of pollen grains in all the varieties excepting Sadaphal was prolate spheroidal, while in Sadaphal it was prolate spheroidal to oblate spheroidal.