Pollen Morphology

Morphological trends in the fossil pollen of Decodon and the paleobiogeographic history of the genus

by Fridgeir Grimsson

2012
Fridgeir Grimsson, David K. Ferguson, Reinhard Zetter
International Journal of Plant Sciences

Intraspecific variation of taeniate bisaccate pollen within Permian glossopterid sporangia, from the Prince Charles Mountains, Antarctica

by Stephen McLoughlin

Reference:
Lindström, S., McLoughlin, S. & Drinnan, A,N. 1997. Intraspecific variation of taeniate bisaccate pollen within Permian glossopterid sporangia, from the Prince Charles Mountains, Antarctica. International Journal of Plant Science, 158: 673-684.

Permineralized sporangia from Late Permian sediments of the Amery Group in the Prince Charles Mountains, East... more Permineralized sporangia from Late Permian sediments of the Amery Group in the Prince Charles Mountains, East Antarctica, are assigned to Arberiella sp. cf. A. africana Pant and Nautiyal. These sporangia contain between 2000 and 3000 taeniate, saccate pollen grains that are predominantly haploxylonoid bisaccate and referable to the palynotaxon Protohaploxypinus limpidus (Balme and Hennelly) Balme and Playford. However, the sporangia also contain greater than 4% of diploxylonoid bisaccate forms comparable to Striatopodocarpidites cancellatus (Balme and Hennelly) Hart 1963, together with sporadic monosaccate and trisaccate grains that, if found dispersed, would be assigned to several different pollen form genera. Morphometric analysis of in situ bisaccate pollen grains and taeniate bisaccate pollen in the dispersed palynoflora indicates that in situ grains occupy only the smaller end of the total size range. The tendency for in situ grains to cluster into two different size groups may reflect differential predispersal expansion of the corpus. The in situ pollen grains are variable in most qualitative and quantitative features used for taxonomic discrimination of dispersed taeniate bisaccate pollen, and this may lead to unreliable estimates of Late Permian floristic diversity if an overly restrictive species delimitation scheme is used.

Some morphological features of Wollemi pine (Wollemia nobilis: Araucariaceae) and their comparison to Cretaceous plant fossils

by Stephen McLoughlin

Reference:
Chambers, T.C., Drinnan, A.N. & McLoughlin, S. 1998. Some morphological features of Wollemi Pine (Wollemia nobilis: Araucariaceae) and their comparison to Cretaceous plant fossils. International Journal of Plant Science, 159: 160-171.

Morphological details of Wollemia nobilis (Wollemi pine) are described and illustrated, and compared with the extant... more Morphological details of Wollemia nobilis (Wollemi pine) are described and illustrated, and compared with the extant genera Agathis and Araucaria and with selected araucarian fossils from the Cretaceous of Australia. Adult and juvenile shoots of Wollemia differ in leaf arrangement, leaf shape, and cuticular features; in these features they are most similar to Araucaria. The cone scales have a long, distal spine reminiscent of Araucaria section Eutacta, but the winged seeds that are ontogenetically free from, and shed independently from, the cone scale are similar to Agathis. Shoots with variable leaf types, Araucaria-like cone scales, and Agathis-like winged seeds are found in several plant fossil assemblages from the Cretaceous of Australia; these fossil conifers, which had been recognized as araucarian, can now be favorably compared with Wollemia. Pollen of Wollemia is indistinguishable from the fossil pollen form-genus Dilwynites, which has a fossil record extending back to the Late Cretaceous in Australia and New Zealand. Reexamination of Mesozoic and Tertiary paleofloras will most probably reveal an important contribution of Wollemia to the fossil record of Araucariaceae.

Pollen grain development is compromised in Arabidopsis agp6 agp11 null mutants.

by Mario Costa

Sílvia Coimbra, Mário Costa, Brian Jones, Marta Adelina Mendes, and Luís Gustavo Pereira.

Abstract
Arabinogalactan proteins (AGPs) are structurally complex plasma membrane and cell wall proteoglycans... more Abstract
Arabinogalactan proteins (AGPs) are structurally complex plasma membrane and cell wall proteoglycans that are
implicated in diverse developmental processes, including plant sexual reproduction. Male gametogenesis (pollen
grain development) is fundamental to plant sexual reproduction. The role of two abundant, pollen-specific AGPs,
AGP6, and AGP11, have been investigated here. The pollen specificity of these proteoglycans suggested that they
are integral to pollen biogenesis and their strong sequence homology indicated a potential for overlapping function.
Indeed, single gene transposon insertion knockouts for both AGPs showed no discernible phenotype. However, in
plants homozygous for one of the insertions and heterozygous for the other, in homozygous double mutants, and in
RNAi and amiRNA transgenic plants that were down-regulated for both genes, many pollen grains failed to develop
normally, leading to their collapse. The microscopic observations of these aborted pollen grains showed
a condensed cytoplasm, membrane blebbing and the presence of small lytic vacuoles. Later in development, the
generative cells that arise from mitotic divisions were not seen to go into the second mitosis. Anther wall
development, the establishment of the endothecium thickenings, the opening of the stomium, and the deposition of
the pollen coat were all normal in the knockout and knockdown lines. Our data provide strong evidence that these
two proteoglycans have overlapping and important functions in gametophytic pollen grain development.

A Late Messinian Palynoflora with a Distinct Taphonomy

by Fridgeir Grimsson

2011
Thomas Denk, Fridgeir Grimsson, Reinhard Zetter, Leifur A Simonarson
Springer
Chapter 9

The Middle Late Miocene Floras - A Window into the Regional Vegetation Surrounding a Large Caldera

by Fridgeir Grimsson

2011
Thomas Denk, Fridgeir Grimsson, Reinhard Zetter, Leifur A Simonarson
Springer
Chapter 7

Aerodynamics of pollen grains involved in sampling efficiency. Abstract Index Conclusions. Thesis by Diego Fernandez-Sevilla

by Diego Fdez-Sevilla

Supervised by Prof. Jean Emberlin 8Worcester Uni.) and Dr. Eckart Schultz (DWD).

Aerobiology studies the passive transport of biological particles in the air. It has many applications including... more Aerobiology studies the passive transport of biological particles in the air. It has many applications including allergy (e.g. hayfever and asthma), crop pollination, forestry, horticulture, and biodeterioration. A central theme is the requirement for detailed information about the residence time of atmospheric particles, which is highly dependent on their settling velocity. This basic parameter is directly related to the aerodynamic behaviour of the pollen grains. It is an essential component for modelling dispersal and atmospheric transport, and it is of special interest for pollen forecasting and transgene escape from genetically modified crops. The sampling efficiency of the sampling methods relies on removing pollen grains from the airflow stream-lines, so differences in aerodynamic behaviour between pollen types could lead to disproportionate representation in the pollen count under variable methodological conditions. Reliable data on real-world pollen settling velocities are needed as little attention has been given to this topic and reported values differ considerably. This research investigates pollen settling velocities in wind tunnel and outdoor experiments, and calculates them from combining deposition and concentration measurement with standard equipment and in different meteorological conditions. For this purpose pollen grains have been sampled in parallel and counted on different sampling media such as impaction surfaces (Hirst-type volumetric trap), deposition plates (Sigma-2 sedimentation sampler) and glass fibre filters (standard particle samplers). Results obtained in this investigation prove that pollen types with different aerodynamic properties express significant differences in their aerodynamic behaviour in following stream-lines. This suggests that, if distortions in the streamlines exist for any kind of pollen sampling method, differences in settling velocity between pollen types could lead to disproportionate representation of certain pollen types under certain meteorological conditions of wind speed and particle settling velocity. Also, results obtained show a negative relationship between atmospheric conditions of vapour pressure deficit (VPD) and pollen settling velocity.Accordingly, atmospheric conditions of VPD have the potential to define the aerodynamic behaviour of the pollen grains. This finding has implications not only in characterising atmospheric conditions for pollen transport but also for airborne pollen sampling. The results obtained in this thesis have applications for further research concerning key areas of the science such as the application of correction factors on the pollen counts obtained, pollen transport modelling and the assessment of factors defining the structure of the pollen cloud.

The Classic Surtarbrandur Floras

by Fridgeir Grimsson

2011
Thomas Denk, Fridgeir Grimsson, Reinhard Zetter, Leifur A Simonarson
Springer
Chapter 5

The Archaic Floras

by Fridgeir Grimsson

2011
Thomas Denk, Fridgeir Grimsson, Reinhard Zetter, Leifur A Simonarson
Springer
Chapter 4

Pollen, fruits, and leaves of Tetracentron (Trochodendraceae) from the Cainozoic of Iceland and western North America and their palaeobiogeographic implications

by Fridgeir Grimsson

2008
Fridgeir Grimsson, Thomas Denk, Reinhard Zetter
Grana

Diverse fossil Onagraceae pollen from a Miocene palynoflora of north-east China: early steps in resolving the phytogeographic history of the family

by Fridgeir Grimsson

2012
Fridgeir Grimsson, Reinhard Zetter, Qin Leng
Plant Systematics and Evolution

Combined LM and SEM study of the Middle Miocene (Sarmatian) palynoflora from the Lavanttal Basin: Part II. Pinophyta (Cupressaceae, Pinaceae and Sciadopityaceae)

by Fridgeir Grimsson

2011
Fridgeir Grimsson, Reinhard Zetter
Grana

Combined LM and SEM study of the Middle Miocene (Sarmatian) palynoflora from the Lavanttal Basin: Part I. Bryophyta, Lycopodiophyta, Pteridophyta, Ginkgophyta, and Gnetophyta

by Fridgeir Grimsson

2011
Fridgeir Grimsson, Reinhard Zetter, Christian Baal
Grana

Lythrum and Peplis from the Late Cretaceous and Cenozoic of North America and Eurasia: New evidence suggesting early diversification within the Lythraceae

by Fridgeir Grimsson

2011
Fridgeir Grimsson, Reinhard Zetter, Christa-Charlotte Hofmann
American Journal of Botany

A taxonomic revision and pollen morphology of the genus Dendrokingstonia (Annonaceae)

by T. Chaowasku

please ask me via cyathostemma[at]yahoo.com for a pdf.

The genus Dendrokingstonia (Annonaceae) is taxonomically revised and palynologically studied. Three species are... more The genus Dendrokingstonia (Annonaceae) is taxonomically revised and palynologically studied. Three species are recognized, one of which, D. gardneri, is described as new to science. One new combination, D. acuminata, is made. The genus occurs from southern Thailand to Peninsular Malaysia and Sumatra. On the basis of macromorphology and pollen characters, it is considered to be related to Monocarpia. Both genera show a combination of macromorphological characters that is rare in the family, i.e. considerably enlarged stigmas, leaves with percurrent tertiary veins, a highly reduced number of carpels per flower and relatively large monocarps with a thick, hard wall. Scanning and transmission electron microscopy show that the pollen grains of Dendrokingstonia and Monocarpia are monosulcate monads with a columellate infratectum and a more or less bulging intine at the sulcus.

Evolució del paisatge vegetal al Camp de Tarragona: estudi pol·línic de la seqüència sedimentològica procedent de l’aiguamoll de la Sèquia Major (la Pineda, Vila-seca)

by Santiago Riera

S. RIERA, Y. MIRAS, S. GIRALT I G. SERVERA (2010)
Marta Prevosti i Josep Guitart (eds.): Ager Tarraconensis 1. Aspectes històrics i marc natural. Historical aspects and natural setting. Documenta 16, Institut d’Estudis Catalans, Institut Català d’Arqueologia Clàssica.

Taxonomic novelties and pollen morphological study in the genus Neo-uvaria (Annonaceae)

by T. Chaowasku

you can access via the link below.

Two new species of Neo-uvaria are described from southern Thailand: Neo-uvaria sparsistellata and N. telopea. Inmore Two new species of Neo-uvaria are described from southern Thailand: Neo-uvaria sparsistellata and N. telopea. In
addition, new combinations are made for two Mitrephora species from the Philippines: N. merrillii and N. viridifolia.
The pollen morphology of eight Neo-uvaria species and three species of the closely related genus Enicosanthum is
studied, using light, scanning electron and transmission electron microscopy. The systematic affinity of Neo-uvaria is
discussed on the basis of macromorphology, pollen morphology and molecular phylogenetics. The genus Enicosanthum
appears to be the closest relative of Neo-uvaria.

Le broyage dans la chaîne de transformation du millet (Panicum miliaceum) : outils, gestes et écofacts

by Bertrand Poissonnier

Co-authored with K. Lunström-Baudais, A.-M. Rachoud-Schneider and D. Baudais
2002, Published  In : Procopiou H. & Treuil R. (dir). Moudre et broyer. I. Méthodes. Actes de la Table-ronde de Clermont-Ferrand, 1995. Paris : Éd. du Comité des travaux historiques et scientifiques, p. 181-209.

Two parallel ethnoarchaeological inquiries were undertaken, one in western Nepal and the other in Vendée (western... more Two parallel ethnoarchaeological inquiries were undertaken, one in western Nepal and the other in Vendée (western France), in order to reconstitute the sequence of operations traditionally employed for processing millet (Panicum miliaceum). Our field work underscored not only the common central role played by the mortar/pestle at the dehusking stage but also revealed two major facultative variations which may be employed to increase the efficacy of mortar/pestle pounding. Thermic treatment before pounding may be applied; this can be a simple heating operation or may include the addition of water to the grain during the heating. Technical improvements of the active head of the pestle were sometimes practised in Vendée and are systematically practised in western Nepal.
The effects of these facultative variations were experimentally evaluated in terms of time ad quality of the product. Without either a thermic treatment of the seed before pounding or the use of a reinforced pestle head, the work of dehusking millet is laborious, the loss of seed important and the quality of the product low. Both thermic treatment of grain and the use of metal armed pestle were already known in Roman times. Depending on the position of thermic treatment in the operative sequence, this artificial heating can lengthen the storage capacity of hulled cereals.
Our experimentation brought to light a botanical marker of thermic treatment: pollen enclosed within the husks of grain becomes characteristically crumpled when exposed to artificial heating, whether or not water is added at this stage. By dating the eventual appearence of this thermic marker within the husks of grain from water-logged archaeological sites, it will become possible to expand our knowledge of the history of thermic treatment in the processing of hulled cereals.

Seedless fruit and methods of Parthenocarpy

by Ravi Dinakar

To view the FREE full text pdf article, please go to www.jes2s.com/pdfs/yam_article.pdf

Also visit the homepage for the new October 2011 edition

Publisher: Ravi Dinakar

The Journal of Experimental Secondary Science, July 2011

Authors: Jonathan Yam and Whitney Hagins*
Department of Science
AP Biology
Lexington High School, 251 Waltham Street, Lexington, MA 02421
*Correspondence: whagins@sch.ci.lexington.ma.us

The process of parthenocarpy involves the
use of phytohormones to change the growth
process of a plant’s... more The process of parthenocarpy involves the
use of phytohormones to change the growth
process of a plant’s fruits and results in fruits
that are generally seedless. In this project,
three phytohormones commonly used in
parthenocarpy were tested for their effects on
the size and quantity of the produced fruits.
The procedures were designed to study patterns
of each hormone’s effect at different amounts
and the effects of cross-pollination on fruit
size. Brassica rapa plants were grown in a uniform
manner and the male organs were removed upon
flowering. After the plants were emasculated, a
number of pistils were exposed to phytohormone
in varying amounts. It was predicted that if
Brassica rapa are grown in a controlled environment,
plants treated with a greater amount of natural
and synthetic auxin phytohormones will produce
larger fruits as compared to plants treated with
less phytohormone. It was also hypothesized that
plants that cross-fertilize will produce a greater
quantity of fruits and more seeds as compared
to plants treated with phytohormone. The
data shows that greater exposure to hormones
generally results in larger fruits, where as all
of the hormone induced fruits are smaller than
fruits produced by cross-pollination.

Pollen grain morphology of selected allergenic species native to Southern South America

by Roberto Pujana