The pollination mechanism and the optimal time of pollination in Douglas-fir (Pseudotsugamenziesii)

1981 ◽  
Vol 11 (1) ◽  
pp. 36-50 ◽  
Author(s):  
John N. Owens ◽  
Sheila J. Simpson ◽  
Marje Molder
Keyword(s):  
Electron Microscopy ◽  
Seed Set ◽  
Pollen Grains ◽  
Douglas Fir ◽  
Optimal Time ◽  
Pollination Mechanism ◽  
Seed Cone ◽  
Poor Seed ◽  
Micropylar Canal ◽  
Scanning Electron

The development of the pollination mechanism and the engulfment of pollen by the stigmatic tip is described for Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) based on scanning electron microscopy. This information is used to determine and explain the optimal time of pollination and amount of pollen needed for maximum seed set. After dormancy the integument tip of the ovule developed into an unequally two-lobed stigmatic tip covered with long unicellular hairs. Most ovules had fully developed stigmatic tips when the seed cone emerged from the bud scales in early April. The conelets remained open and the stigmatic tip was most receptive for at least 4 days. Pollen freely sifted down between the bracts and ovuliferous scales and adhered to the stigmatic hairs. Six days after the conelets became receptive, stigmatic hairs around the micropyle began to collapse and were ungulfed with the entangled pollen into the micropyle. Also, ovuliferous scales began to thicken, restricting movement of pollen to the stigmatic tips. By 8–10 days after conelets became receptive, the stigmatic tips were completely engulfed, the ovuliferous scales had thickened enough to close the conelet, and the conelet had begun to bend down.Maximum seed set occurred when (1) cones were pollinated within 4 days after seed-cone buds had emerged half of the way out of their bud scales; (2) a minimum of 0.2 g of pollen was used per pollination bag; (3) a minimum of 11 pollen grains adhered to each stigmatic tip; and (4) at least 3 pollen grains were taken into each micropylar canal. The engulfing process occurred at the same rate and in the same manner regardless of whether living or heat-killed pollen was present or absent on the stigmatic surface. Poor seed set as it related to the pollination mechanism is discussed.

The pollination mechanism in yellow cypress (Chamaecyparisnootkatensis)

1980 ◽  
Vol 10 (4) ◽  
pp. 564-572 ◽  
Author(s):  
John N. Owens ◽  
Sheila J. Simpson ◽  
Marje Molder
Keyword(s):  
Lipid Droplets ◽  
Pollen Grains ◽  
Water Droplets ◽  
Pollination Mechanism ◽  
Seed Cone ◽  
Pollination Drop ◽  
Micropylar Canal ◽  
The One ◽  
Cuticular Surface

Mature, dry, one-celled pollen was formed before pollen cones became dormant in the fall. Pollen averaged 27 μm in diameter, was irregular in shape, nonsaccate, and the surface was reticulate to tegillate-baculate and irregularly covered with orbicules. The pollen contained several large lipid droplets and no starch. No changes occurred in pollen during dormancy and pollen was shed at the one- or two-celled stage during the last half of March.All ovules were initiated and became flask shaped before seed-cone dormancy. No changes occurred in ovules during dormancy. Seed cones ended dormancy in early March, enlarged and opened, exposing the ovules. A pollination drop was produced by a breakdown of cells at the tip of the nucellus. A large pollination drop was exuded from each ovule in a cone but exudation did not occur at the same time in all ovules. Each ovule exuded and withdrew a pollination drop two to four times before the pollination drop was permanently withdrawn. Each ovule was receptive for a few days and each cone was receptive for about 1 week. The pollination drops were withdrawn in the presence or absence of pollen but were withdrawn more rapidly after pollen entered the pollination drop. The cuticular surface of the bract-scales prevented wetting of the surface and caused the beading of water droplets, which in turn could carry pollen to the micropyle. Pollen grains entering a pollination drop were withdrawn inside the drop into the micropyle. Cells lining the micropylar canal enlarged and sealed the canal while bract-scales enlarged and buried the ovules within the cone.

scholarly journals Pollen morphology of Iranian Dracocephalum L. (Lamiaceae) and its taxonomic significance

2015 ◽  
Vol 22 (2) ◽  
pp. 99-110 ◽  
Author(s):  
Maryam Naderifar ◽  
Ali Sonboli ◽  
Abbas Gholipour
Keyword(s):  
Electron Microscopy ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Polar View ◽  
Taxonomic Significance ◽  
Infrageneric Classification ◽  
Exine Ornamentation ◽  
Plant Taxon ◽  
Scanning Electron

Pollen morphology of 11 Iranian Dracocephalum L. species was investigated using light and scanning electron microscopy to evaluate their taxonomic significance for the infrageneric classification of the genus. Pollen grains of all examined taxa were isopolar, hexacolpate, circular in polar view and spheroidal to prolate in equatorial view (P/E = 1.0?2.0). The smallest pollen grains were observed in D. aucheri (P = 29.7 ?m, E = 22.6 ?m), while the largest pollen was found in D. lindbergii (P = 45.1 ?m, E = 33.7 ?m). The highest and lowest apocolpium index (AI) were measured in D. aucheri (AI = 0.27) and D. surmandinum (AI = 0.08), respectively. Colpus membrane was egranulate in all examined species except for D. multicaule and D. ghahremanii. The main exine ornamentation type was characterized as bireticulate including five different subtypes. The results revealed that the exine ornamentation is a diagnostic character useful for the classification of Dracocephalum.Bangladesh J. Plant Taxon. 22(2): 99-110, 2015 (December)

scholarly journals Pollen morphology of the genus Eremanthus Less. (Vernonieae, Asteraceae)

2012 ◽  
Vol 26 (1) ◽  
pp. 46-57 ◽  
Author(s):  
BenoÎt Loeuille ◽  
Raquel Maria Batista Souza-Souza ◽  
Vanessa Holanda Righetti Abreu ◽  
Cláudia Barbieri Ferreira Mendonça ◽  
Vania Gonçalves-Esteves
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pollen Morphology ◽  
Additional Data ◽  
Phylogenetic Reconstruction ◽  
Pollen Grains ◽  
Prolate Spheroidal ◽  
Oblate Spheroidal ◽  
Quantitative Characters ◽  
Scanning Electron

In order to evaluate the significance of the pollen morphology for generic and infrageneric taxonomy of the genus Eremanthus (Vernonieae, Asteraceae), and to provide additional data for its phylogenetic reconstruction, the pollen of 20 of the 23 species of the genus was examined using light and scanning electron microscopy. Acetolysed pollen grains were measured, described, and illustrated using light microscopy, while non-acetolysed pollen grains were analyzed using scanning electron microscopy. Pollen grains of these species are isopolar, oblate-spheroidal in most of the species, more rarely prolate spheroidal or suboblate, subtriangular amb, tricolporate and subechinolophate. The variation among quantitative characters does not correlate with the macromorphological subdivision of the genus or with the generic or specific limits.

scholarly journals Pollen morphology of Ukrainian species of the genus Pedicularis L. (Orobanchaceae Vent.)

2012 ◽  
Vol 24 (1) ◽  
pp. 5-13 ◽  
Author(s):  
Olena M. Peregrym ◽  
Zoya M. Tsymbalyuk ◽  
Sergei L. Mosyakin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Taxonomic Revision ◽  
Palynological Data ◽  
First Time ◽  
Scanning Electron

Abstract Pollen grains of 10 species of Pedicularis occurring in Ukraine were investigated using light and scanning electron microscopy. Palynological data on 6 species are reported for the first time. General pollen morphology of the genus Pedicularis is presented. Three types of apertures (2-syncolpate, 3-colpate, and 3-syncolpate) and seven subtypes of sculpture (3-syncolpate pilate, 3-syncolpate microscabrate-tubeculate, 2-syncolpate microscabrate, 2-syncolpate microscabrate-tubeculate, 2-syncolpate microscabrate-tubeculate-perforate, 2-syncolpate microfoveolate, and 2-syncolpate microscabrate-perforate) are indentified. The subgenus Pedicularis is heterogeneous in its types of apertures and sculpture of the surface, which indicates the need of further taxonomic revision of the group.

scholarly journals Pollen morphology of the Balkan-Carpathian endemic Campanula lingulata Waldst. & Kit. (Campanulaceae)

2016 ◽  
pp. 75-82
Author(s):  
Marina Macukanovic-Jocic ◽  
Snezana Jaric
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Light Microscopy ◽  
Endemic Species ◽  
Pollen Morphology ◽  
Average Length ◽  
Pollen Grains ◽  
Polar Axis ◽  
First Time ◽  
Scanning Electron

Palynomorphological characteristics of Campanula lingulata, the Balkan-Carpathian endemic species growing in Serbia, have been investigated using light microscopy and scanning electron microscopy for the first time, in order to provide some information helpful for a better understanding of the taxonomic position of this species within the genus, as well as to contribute to the pollen atlas of Serbian apiflora. The pollen grains are radially symmetrical, isopolar, 3-zonoporate and medium-sized monads oblate-sphaeroidal in shape. Mean of the polar axis (P) is 27.6?1.9 ?m, while the average length of the equatorial axis (E) is 28.8?1.6 ?m. The apertures are operculate. The sculpturing pattern of the exine is microre?ticulate-microechinatae. The exine surface is covered with evenly distributed supratectal spinules of variable length and sparse granules. The longest supratectal spinules are 0.64?0.05 ?m in length and the smallest sculptural elements are less than 0.2 ?m high. The microechinae density per sample area of 5 ?m x 5 ?m averages 17.4?2.4.

scholarly journals ELECTRON MICROSCOPIC STUDIES OF SOME ANTICANCER PLANTS POLLEN GRAINS

2021 ◽  
Vol 9 (10) ◽  
pp. 1386-1393
Author(s):  
Jayshree Sandesh Thaware ◽  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Morphological Characters ◽  
Electron Microscopic ◽  
Plant Parts ◽  
Morphological Studies ◽  
Datura Metel ◽  
Scanning Electron

Pollen is appropriately referred by some as Golden dust extremely valuable on account of their tremendous applications in science, industries and public health. No other plant part even though extremely tiny in size is packed with so much information and power. Similar to other plant parts, pollen characters are so varied that the classification system of plants can be built up entirely on the basis of pollen morphology.Palynology is the distinct branch of biology that deals with the dispersed microscopic tiny living and fossil entities including pollen grains, spores, algal and fungal fragments and others. An important aspect of Palynology is the Pollen morphology. The importance of Palynology in taxonomic and phylogenetic consideration of plants is well known. The changes occurring through hybridization and years of cultivation are reflected in pollen morphology. The scope and interest in the study of pollen morphology have widened with the advent of Scanning Electron Microscopy (SEM) and with regards to unipalynous taxa particularly the understanding of finer morphology is of fundamental importance. SEM gives a correct understanding of exine surface as the electron photographs of the surface replica of the exine provides the exact picture of the ornamentation pattern. The variation in the pollen morphological characters helps in the classification of plant taxa and their assessment of their phylogenetic relationship. In the present investigation, the pollen morphological studies were carried out of some ethnomedicinal plants like Catharanthus roseus, Allamanda cathartica, Datura metel, Brassica juncea, Raphanus sativus and Cleome viscosa pollen grains by Scanning electron microscopy. All that they possess anticancer characteristics in common.

Pollen morphology of Sabinaria magnifica (Cryosophileae, Coryphoideae, Arecaceae)

Phytotaxa ◽  
2015 ◽  
Vol 207 (1) ◽  
pp. 135 ◽  
Author(s):  
Giovanni Raul Bogota ◽  
Carina Hoorn ◽  
Wim Star ◽  
Rob Langelaan ◽  
Hannah Banks ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscopy ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
The Other ◽  
Transmission Electron ◽  
Palm Species ◽  
Scanning Electron

Sabinaria magnifica is so far the only known species in the recently discovered tropical palm genus Sabinaria (Arecaceae). Here we present a complete description of the pollen morphology of this palm species based on light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We also made SEM-based comparisons of Sabinaria with other genera within the tribe Cryosophileae. Pollen grains of Sabinaria magnifica resemble the other genera in the heteropolar, slightly asymmetric monads, and the monosulcate and tectate exine with perforate surface. Nevertheless, there are some clear differences with Thrinax, Chelyocarpus and Cryosophila in terms of aperture and exine. S. magnifica differs from its closest relative, Itaya amicorum, in the exine structure. This study shows that a combination of microscope techniques is essential for the identification of different genera within the Cryosophileae and may also be a necessary when working with other palynologically less distinct palm genera. 

Palynological analysis of five selected Onosma taxa

Biologia ◽  
2008 ◽  
Vol 63 (2) ◽  
Author(s):  
Filippo Maggi ◽  
Vladislav Kolarčik ◽  
Pavol Mártonfi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Chromosome Number ◽  
Pollen Grains ◽  
Pollen Size ◽  
Palynological Analysis ◽  
Positive Correlation ◽  
Pollen Characters ◽  
Scanning Electron

AbstractPollen size and exine structure of the following five Onosma L. species from Slovakia and Italy were studied by light and scanning electron microscopy: Onosma echioides, O. tornensis, O. visianii, O. arenaria, and O. pseudoarenaria. Among the taxa studied, O. echioides has the smallest pollen grains in average (10.5–17.5 × 8.0–14.5 µm), and O. pseudoarenaria the largest grains in average (15.3–20.5 × 12.3–16.3 µm). Pollen grains of all 5 species are small sized, 3-syncolporate, subprolate, heteropolar, with ovate equatorial outlines and circular to rounded triangular polar outlines; the tectum is microechinate. A positive correlation is found between pollen size and chromosome number. The value of pollen characters for taxonomic purposes and the position of the taxa studied within the genus Onosma are discussed.

Contribution to the pollen morphology of Tragopogon (Asteraceae) in Turkey

Phytotaxa ◽  
2018 ◽  
Vol 361 (2) ◽  
pp. 168 ◽  
Author(s):  
MUTLU GÜLTEPE ◽  
SERDAR MAKBUL ◽  
SEDA OKUR ◽  
KAMİL COŞKUNÇELEBİ
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Principal Component ◽  
Numerical Analyses ◽  
Oblate Spheroidal ◽  
Pore Length ◽  
Principal Component Analyses ◽  
Scanning Electron

The pollen morphology of 25 Tragopogon L. taxa (including four subspecies and four varieties) distributed in Turkey was studied under light and scanning electron microscopy. It was observed that pollen grains of the examined Tragopogon taxa are suboblate and oblate-spheroidal in shape, and 3-zonocolpororate with fifteen lacunae. The lenghts of the polar axes and equatorial axes range from 31.57 to 40.35 µm and 35.32 to 44.65 µm, respectively. Numerical analyses show that the length of equatorial axis and the pore length are the most valuable characters among nineteen palynological traits for separating the examined taxa. The general palynological characteristics of the examined taxa allow some taxonomical evaluations for the genus. However, the results of cluster and principal component analyses did not support the division of the genus at any subgeneric level; neither did the ligule colour, as reported in the literature.

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