Pollen movement in the micropylar canal ofLarix and its simulation

1997 ◽  
Vol 110 (2) ◽  
pp. 259-264 ◽  
Author(s):  
Tokushiro Takaso ◽  
John N. Owens
Keyword(s):  
Micropylar Canal ◽  
Pollen Movement

Direct and Indirect Estimates of Seed Versus Pollen Movement Within a Population of Ponderosa Pine

Evolution ◽  
1998 ◽  
Vol 52 (1) ◽  
pp. 61 ◽  
Author(s):  
Robert G. Latta ◽  
Yan B. Linhart ◽  
David Fleck ◽  
Michael Elliot
Keyword(s):  
Ponderosa Pine ◽  
Pollen Movement

TRACKING PAPAYA POLLEN MOVEMENT WITH THE GUS TRANSGENE MARKER

2007 ◽  
pp. 183-187 ◽  
Author(s):  
R.M. Manshardt ◽  
C.L. Mello ◽  
S.D. Lum ◽  
L. Ta
Keyword(s):  
Pollen Movement

The Respiratory Mechanisms of Some Insect Eggs

1950 ◽  
Vol s3-91 (16) ◽  
pp. 429-452
Author(s):  
V. B. WIGGLESWORTH ◽  
J.W. L. BEAMENT
Keyword(s):  
Porous Structure ◽  
Outer Layer ◽  
Injection Technique ◽  
Protein Layer ◽  
Insect Eggs ◽  
Quantitative Evidence ◽  
Free Air ◽  
Cobalt Sulphide ◽  
Micropylar Canal

By the use of the cobalt sulphide injection technique the distribution of air in the shell of a number of insect eggs has been studied. Air is usually confined to an inner layer of porous protein, connected with the atmosphere through pores of varying type which are likewise filled with spongy material. In Rhodnius the ‘resistant protein layer’ which lines the shell is the porous structure and the ‘pseudomicropyles’ connect this layer to the exterior. The arrangement in Cimex is similar. In Oncopeltus the spongy walls of the ‘sperm cups’ convey air to a porous inner layer. After laying, the lumen of each cup (the micropylar canal) is occluded with solid cement. In Dixippus the so-called ‘micropyle’ in the ‘scar’ of the egg is the respiratory pore. It is filled with spongy protein containing air and conducts the air to the spongy inner layer of the endochorion. As the egg develops and its contents are reduced in volume, free air collects between the two layers of the endochorion in the region of the pore. In Blattella an elaborate stigmatic apparatus which is moulded in the crista of the oöheca conveys air to a spongy process at the upper pole of the egg and so to a thin porous air-filled layer which lines the chorion. In Bombyx and Ephestia a thin porous inner layer of the chorion containing air communicates with the exterior through scattered pores containing air-filled spongy material. In the eggs of Diptera the chorion consists of tapering columns with spongy walls which unite the cement-covered outer layer to a spongy inner layer containing air. The horns on the Drosophila egg and the dorsal folds on the Calliphora egg provide respiratory outlets for this system. The spaces between the columns contain liquid in Calliphora and Drosophila; in Syrphus these spaces are greatly enlarged and contain air. The spongy layers may become filled with air in eggs which are still bathed in fluid in the oviduct, or in which water is present in adjacent parts of the shell. The mechanism of filling is discussed. In the case of Rhodnius there is quantitative evidence that the system will provide for the respiratory needs of the egg.

scholarly journals Pollen movement in a natural population of Arisaema serratum (Araceae), a plant with a pitfall-trap flower pollination system

2005 ◽  
Vol 92 (7) ◽  
pp. 1114-1123 ◽  
Author(s):  
T. Nishizawa ◽  
Y. Watano ◽  
E. Kinoshita ◽  
T. Kawahara ◽  
K. Ueda
Keyword(s):  
Natural Population ◽  
Pitfall Trap ◽  
Pollination System ◽  
Flower Pollination ◽  
Pollen Movement

Sexual reproduction in western red cedar (Thuja plicata)

1980 ◽  
Vol 58 (12) ◽  
pp. 1376-1393 ◽  
Author(s):  
John N. Owens ◽  
M. Molder
Keyword(s):  
Sexual Reproduction ◽  
Seed Production ◽  
Low Temperatures ◽  
Female Gametophyte ◽  
Seed Set ◽  
Thuja Plicata ◽  
Insect Damage ◽  
Red Cedar ◽  
Pollination Drop ◽  
Micropylar Canal

Pollen cones and seed cones ended dormancy in mid-February, microsporogenesis occurred in late February, and pollination occurred for about 1 week in early March. Pollen was shed at the two-celled stage. Pollination drops were exuded from only a few ovules at one time. Pollen contacting the pollination drop was rapidly taken in. The pollination drop was withdrawn into the micropyle which was later sealed by enlargement of cells lining the micropylar canal. Megasporogenesis occurred in late February but female gametophytes did not mature and fertilization did not occur until late May. An archegonial complex formed containing seven to nine archegonia, of which several usually were fertilized. Proembryo development varied depending upon the size and shape of the archegonia. Usually, a 12-celled, three-tiered proembryo formed by mid-June. Cleavage polyembryony was not observed. Embryos were mature by mid-August and most seed was shed in September and October.The potential seed set was only 16 seeds per cone and filled seed averaged only 2.6 per cone. Most potential seed was lost because of early ovule abortion from unknown causes, insect damage, or low temperatures at or shortly after pollination. Some potential seeds were lost because the ovules were not pollinated or the embryos aborted. These seeds were soft but nearly normal appearing and contained spongy female gametophyte tissue. Methods of maximizing seed production are suggested.

The pollination mechanism and development after bud burst of cones of Larix laricina

1991 ◽  
Vol 69 (6) ◽  
pp. 1179-1187 ◽  
Author(s):  
G. R. Powell ◽  
Kathleen J. Tosh
Keyword(s):  
Key Words ◽  
Seed Size ◽  
Larix Laricina ◽  
Bud Burst ◽  
Scale Growth ◽  
Pollination Mechanism ◽  
Seed Cone ◽  
Cone Development ◽  
Micropylar Canal ◽  
Pollen Cone

Pollen-cone and seed-cone development, from bud burst to maturity, was investigated on Larix laricina (Du Roi) K. Koch in three young plantations. The pollination mechanism was emphasized. Pollen cones grew rapidly to shed pollen, shrivelled, and remained on the trees for a year or more. Pollen was directed to the ovular regions by the bracts of the seed cones. Pollen adhered among papillae on the larger of two integument extensions. Degeneration of the centre of the papillate integument tip caused a collapse that drew pollen in as the papillate rim grew inward. This ingrowth was joined by that of the smaller integument extension, resulting in a sealed tubular structure that enclosed a dry micropylar canal. Pollen was held by the ingrown plug of degenerated tissue as the nucellus tip expanded into the base of the canal. As this occurred, the ovules, with or without pollination, grew to ultimate seed size, and the initially small ovuliferous scales overgrew the bracts. First bract, then ovuliferous-scale growth was associated with a double-sigmoid form of cone elongation. In mature cones the bracts decreased and the ovuliferous scales (except near the tip) increased in size acropetally. Key words: bract, integument, ovuliferous scale, pollen cone, seed cone, tamarack or eastern larch.

Among-population pollen movement and skewed male fitness in a dioecious weed

2015 ◽  
Vol 17 (7) ◽  
pp. 2147-2161 ◽  
Author(s):  
Tara Hopley ◽  
Alexander B. Zwart ◽  
Andrew G. Young
Keyword(s):  
Male Fitness ◽  
Pollen Movement

scholarly journals Mate-Searching Behaviour of Common and Rare Wasps and the Implications for Pollen Movement of the Sexually Deceptive Orchids They Pollinate

PLoS ONE ◽  
2013 ◽  
Vol 8 (3) ◽  
pp. e59111 ◽  
Author(s):  
Myles H. M. Menz ◽  
Ryan D. Phillips ◽  
Kingsley W. Dixon ◽  
Rod Peakall ◽  
Raphael K. Didham
Keyword(s):  
Mate Searching ◽  
Searching Behaviour ◽  
Sexually Deceptive Orchids ◽  
Pollen Movement

Pollen movement in a Malus sylvestris population and conclusions for conservation measures

2015 ◽  
Vol 15 (1) ◽  
pp. 12-20 ◽  
Author(s):  
Stefanie Reim ◽  
Anke Proft ◽  
Simone Heinz ◽  
Frank Lochschmidt ◽  
Monika Höfer ◽  
...  
Keyword(s):  
Large Scale ◽  
Spatial Genetic Structure ◽  
Pollen Dispersal ◽  
Paternity Analysis ◽  
Open Pollination ◽  
Malus Sylvestris ◽  
Conservation Measures ◽  
True Type ◽  
Dispersal Distances ◽  
Pollen Movement

Knowledge of pollen movement and frequency of interspecific hybridization in fragmented populations of rare species is a prerequisite for the implementation of conservation measures. In a large-scale study area (14,000 hectares) we analysed 297 Malus sylvestris trees with nine nuclear microsatellite markers. After open pollination of 564 offspring from 51 mother trees located in seven harvesting sites were investigated and genetic paternity analysis was performed. The paternal parent was identified for 213 offspring and the pollen dispersal distances between mother and pollen source were calculated. A large proportion of detected pollination events (42.4%) were observed within a radius of 50 m of the mother tree. The comparison of different tree densities indicated that with decreasing density the pollen dispersal distances increase. We observed pollination over long distances with a maximum of 10.7 km which is probably one of the reasons for a low spatial genetic structure within the M. sylvestris population and a stable genetic diversity in the offspring. Incorporating microsatellite data of 21 apple cultivars, a hybridization frequency of nearly 8% was determined. With decreasing tree density the number of hybridization events increased. Based on the results of our study an enhancement of the density of existing M. sylvestris populations is recommend to reduce the likelihood of hybridization. The production of young plants originated from seeds collected after open pollination is not advisable. Instead of that the seedlings for further reintroduction measures should be produced by controlled crossings in seed orchards to ensure ‘true type’ M. sylvestris individuals.

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