Fine structure of Rossipollis reticulatus from the Upper Cretaceous of southern Sweden

2004 ◽  
Vol 82 (7) ◽  
pp. 927-937 ◽  
Author(s):  
Annie Skarby ◽  
Marta A Morbelli ◽  
John R Rowley
Keyword(s):  
Fine Structure ◽  
Upper Cretaceous ◽  
Pollen Grains ◽  
Fossil Pollen ◽  
Fluvial Sediments ◽  
Southern Sweden ◽  
Innermost Layer ◽  
Pollen Sacs

Dispersed monosulcate pollen identified as Rossipollis reticulatus Ross and similar pollen in two pollen sacs from a single anther were recovered from Upper Cretaceous fluvial sediments in southern Sweden. In most pollen grains the wall consists of a foot layer, an inner solid reticulum, crowned by columellae, which appear as an infratectal reticulum, and a tectum with irregularly spaced fine perforations. An additional papillate innermost layer, interpreted as a transitory endexin, is present in some pollen grains. A monocotyledonous origin is indicated by the configuration of exine and aperture along with the presence of papillate endexine structures in grains considered to have aborted at earlier stages of development.Key words: Cretaceous, fossil pollen, endexine, monocots.

Evidence of an Asia to North America dispersal of palynomorphs in the Late Cretaceous

2015 ◽  
Vol 52 (8) ◽  
pp. 537-541 ◽  
Author(s):  
Dennis R. Braman
Keyword(s):  
North America ◽  
Upper Cretaceous ◽  
Pollen Grains ◽  
Northern China ◽  
Fossil Pollen ◽  
Long Distance ◽  
Fossil Species ◽  
Life Styles ◽  
Large Size ◽  
Complex Morphology

The fossil pollen genus Morinoipollenites has been frequently reported in strata from the Upper Cretaceous of northern China and southeastern Russia. Pollen grains belonging to a single fossil species, Morinoipollenites normalis, have been only rarely encountered in Upper Cretaceous strata of North America. Just five specimens of Morinoipollenites have been recovered from sites of definite or probable Maastrichtian age in Alaska, Alberta, Saskatchewan, and Colorado. It is argued that the rarity in North America, common Asian occurrences, large size of pollen grains, and complex morphology of the pollen favour these pollen grains having been transported to North America from Asia by some vector. The transporting vector would most likely have been a flying organism based on the life styles of the producing plants and transporting organisms, long distance of transport, and morphology of the pollen grains.

scholarly journals Spatially Continuous Land-Cover Reconstructions Through the Holocene in Southern Sweden

Ecosystems ◽  
2021 ◽  
Author(s):  
Robert O’Dwyer ◽  
Laurent Marquer ◽  
Anna-Kari Trondman ◽  
Anna Maria Jönsson
Keyword(s):  
Land Cover ◽  
Regional Scale ◽  
Coniferous Forest ◽  
Reconstruction Algorithm ◽  
Fossil Pollen ◽  
Conifer Forest ◽  
Southern Sweden ◽  
The Holocene ◽  
Simple Kriging ◽  
Pollen Records

AbstractClimate change and human activities influence the development of ecosystems, with human demand of ecosystem services altering both land use and land cover. Fossil pollen records provide time series of vegetation characteristics, and the aim of this study was to create spatially continuous reconstructions of land cover through the Holocene in southern Sweden. The Landscape Reconstruction Algorithm (LRA) was applied to obtain quantitative reconstructions of pollen-based vegetation cover at local scales, accounting for pollen production, dispersal, and deposition mechanisms. Pollen-based local vegetation estimates were produced from 41 fossil pollen records available for the region. A comparison of 17 interpolation methods was made and evaluated by comparing with current land cover. Simple kriging with cokriging using elevation was selected to interpolate the local characteristics of past land cover, to generate more detailed reconstructions of trends and degree of variability in time and space than previous studies based on pollen data representing the regional scale. Since the Mesolithic, two main processes have acted to reshape the land cover of southern Sweden, originally mostly covered by broad-leaved forests. The natural distribution limit of coniferous forest has moved southward during periods with colder climate and retracted northward during warmer periods, and human expansion in the area and agrotechnological developments has led to a gradually more open landscape, reaching maximum openness at the beginning of the 20th century. The recent intensification of agriculture has led to abandonment of less fertile agricultural fields and afforestation with conifer forest.

Fine structure of sperm cells in pollen grains ofBeta

PROTOPLASMA ◽  
1969 ◽  
Vol 68 (1-2) ◽  
pp. 237-240 ◽  
Author(s):  
Lynn L. Hoefert
Keyword(s):  
Fine Structure ◽  
Pollen Grains ◽  
Sperm Cells

Fossil pollen grains of Asteraceae from the Miocene of Patagonia: Nassauviinae affinity

2008 ◽  
Vol 151 (1-2) ◽  
pp. 51-58 ◽  
Author(s):  
Viviana Barreda ◽  
Luis Palazzesi ◽  
María Cristina Tellería
Keyword(s):  
Pollen Grains ◽  
Fossil Pollen

scholarly journals Can Palynology be used for Reconstructing the Evolutionary History of Maize Agriculture?

2000 ◽  
Vol 14 (1) ◽  
Author(s):  
Grant D. Zazula
Keyword(s):  
Pollen Analysis ◽  
Evolutionary History ◽  
Morphological Characteristics ◽  
Pollen Grains ◽  
Fossil Pollen ◽  
Evolutionary Transition ◽  
Archaeological Evidence ◽  
Maize Agriculture ◽  
History Of ◽  
Pollen Records

The lack of archaeological or macrobotanical evidence that directly links wild teosinte grass with early domesticated maize requires the exploration of alternative methodologies to document this evolutionary transition. The morphological characteristics and measurements for maize, teosinte and Tripsacum pollen are presented to determine if they display sufficient differentiation to be distinguished in fossil pollen records. Analysis of the data reveals a lack of distinguishing morphological characteristics between the pollen grains of these taxa and prevents palynology from be an effective method in documenting the evolutionary history of maize agriculture. Current methods of pollen analysis cannot be employed to document the evolution of teosinte to maize in the Tehuacan Valley of Mexico and pollen is not likely to provide an earlier record of this transition than what is found in the macrobotanical or archaeological evidence.

scholarly journals Anatomical Characteristics of Petalized Anther Abortion in Male Sterile Camellia oleifera Plants

2021 ◽  
pp. 1-13
Author(s):  
Yang Hu ◽  
Chao Gao ◽  
Quanen Deng ◽  
Jie Qiu ◽  
Hongli Wei ◽  
...  
Keyword(s):  
Germination Rate ◽  
Pollen Grains ◽  
Relative Activity ◽  
Control Group ◽  
Camellia Oleifera ◽  
Male Sterile ◽  
Flower Bud ◽  
Triphenyltetrazolium Chloride ◽  
Pollen Sacs

Petalized anther abortion is an important characteristic of male sterility in plants. The male sterile plants (HB-21) evincing petalized anther abortion previously discovered in a clone population of the Camellia oleifera cultivar Huashuo by our research group were selected as the experimental material in this study. Using plant microscopy and anatomic methods and given the correspondence between external morphology and internal structure, we studied the anatomic characteristics of petalized anther abortion (with a fertile plant as the control group) in various stages, from flower bud differentiation to anther maturity, in hopes of providing a theoretical basis for research on and applications of male sterile C. oleifera plants, a new method for the selection of male sterile C. oleifera cultivars, and improvements in the yield and quality of C. oleifera. In this study, the development of anthers in C. oleifera was divided into 14 stages. Petalized anther abortion in male sterile plants was mainly initiated in the second stage (the stage of sporogenous cells). Either the petalized upper anther parts did not form pollen sacs, or the entire anthers did not form pollen sacs. The lower parts of some anthers could form deformed pollen sacs and develop, and these anthers could be roughly divided into two types: fully and partially petalized anthers. Abnormal callose and the premature degradation of the tapetum occurred in the pollen sacs formed by partially petalized anthers during the development process, resulting in the absence of inclusions in the pollen grains formed. Small quantities of mature pollen grains withered inward from the germinal furrows, exhibiting obvious abortion characteristics. The relative in vitro germination rate of the pollen produced by the partially petalized anthers of sterile plants was 11.20%, and the relative activity of triphenyltetrazolium chloride was 3.24%, while the fully petalized anthers did not generate pollen grains. Either the petalized anthers in male sterile plants did not produce pollen, or the vitality of the small amounts of pollen produced by sterile plants was very low compared with that of fertile plants. Such male sterile plants could be used to select correct clones and have good prospects for application in production.

scholarly journals Structural Analysis of Reproductive Development in Staminate Flowers of Laurus nobilis L.

2012 ◽  
Vol 4 (1) ◽  
pp. 31-43 ◽  
Author(s):  
Özlem AYTÜRK ◽  
Meral ÜNAL
Keyword(s):  
Flower Development ◽  
Pollen Grains ◽  
Female Flower ◽  
Sem Analysis ◽  
Floral Meristem ◽  
Anther Wall ◽  
Laurus Nobilis ◽  
Initial Development ◽  
Mother Cells ◽  
Pollen Sacs

Male (staminat) flower development, being separated in 8 phases, was investigated in Laurus nobilis (Lauraceae) through the usage of histological sections and scanning electron microscopy (SEM) analysis. Flower development starts when apical meristem differentiates, followed by the conversion of this structure to floral meristem. Initial development phases comprise incidents similar to the ones of the female flower. 4 tepals and 8-10 stamens primordia develop through floral meristem in turn. In early stages of the development, sexual dimorphism occurs when the carpel primordium arrests. Filaments carry 2 nectaries in stamens which arise in 3 whorls. Anther wall consists of epidermis, endothecium, 2 or 3 middle layers and a single-layered glandular tapetum. Anthers are bisporangiate. Meiotic division is regular in pollen mother cells, and pollen grains do not contain aperture. Beside the pollen scattered individually within the pollen sacs, groups which contain some pollen tied to each other are rarely observed, as well. Pollen grains seldom germinate within microsporangium. Anthers are opened with 2 valves which widen from the base through the top. Accumulation of polysaccharides, lipids and proteins were identified by histochemical methods in stamens. These organic substances are greater within and around the vascular bundle compared to other tissues.

A contribution to the tertiary occurrence of the genus Dacrydium in the Australian region

1953 ◽  
Vol 1 (3) ◽  
pp. 474 ◽  
Author(s):  
IC Cookson ◽  
KM Pike
Keyword(s):  
Pollen Grains ◽  
New Guinea ◽  
Fossil Pollen ◽  
Australian Region ◽  
Living Species

Foliage shoots and seeds of a new Tertiary species, Dacydium rhomboideum, are described; the affinity of D. rhomboideum is discussed.A new sporomorph, Dacrydiumites florinii, is proposed for fossil pollen grains, similar to those of certain species of Dacrydium, isolated from Tertiary deposits in Australia, Tasmania, and New Guinea. Descriptions of the pollen grains of the living species Dacrydium araucurioides and Dacrydium balansae are included.

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