Pollen Slides and Description
Lilly and Hazel Pollen
Pollen Slides and Description
Pollen is a cluster of pollen grains of seed plants. Pollen is the male gametophyte, which develops in the microsporangium of microspores, and performs the function of pollination, that is, fertilization of the female gametophyte located in the ovule.
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Pollen develops in the anthers of stamens. Bordering the outer skin layer of young anther tangential partitions is divided into two layers, of which the outer wall produces pollen chamber, and gives rise to internal Archespores consisting of producing, or parent, pollen cells. Then pollen mother cells usually grow in size and thicken the shell, or they are interconnected (most dicots) or disconnected (many monocots).
Each producing cell is then divided into four specially producing cells or by repeated halving (monocots), or obtained by dividing around the four cores having four cells immediately cladding (most dicots).
The content within each special producing cell is clothed to be the new shell, differentiating into the outer stout layer the exine, and internal intine. The quantity of pollen cells ranges from 0.0025 to 0.25 mm. According to the length of the polar axis about the equatorial diameter of pollen grains, one can distinguish oblate, spheroidal, oblong, and other forms of pollen grains. They are predominantly ellipsoidal or spherical, sometimes faceted or angular. The outer layer (exine) is often covered by various sculptures in the form of ridges, bumps, spikes, etc., sometimes dry and smooth.
It is possible to consider the following features of the structure of pollen grains:
1) the size of pollen grains in microns;
2) the nature of the furrows on the surface of pollen, if any;
3) details of the structure of the outer shell of pollen grains - exine;
4) the nature of pores on the surface of the pollen grains, if they exist;
5) the structural details of the inner lining of motes intine;
6) the ratio of the thickness: intine/exine;
7) the length of the polar axis.
The polar axis is an imaginary line extending through the body of the pollen grains from the outer (distal) surface to the inner (proximal). In cases, where the pollen has a complex structure, i.e. consists of 4 or 8 pollen grains the geometrical axis of each pollen grain converges in the geometric center of this complex pollen (as we can see in all three cases of pollen, which are under our research).
Pollen grains are divided by size into classes defined by the maximum length of the polar axis and the equatorial diameter of the grain. It is distinguished as very small (size is less than 10 microns), small (10-25 mm), medium (25-50 mm), large (50-100 microns), very large (100-200 microns), and giant (more than 200 microns) pollen grains. Pollen that causes pollinosis has small and medium sizes, such as given pollen of the ivy, lily, hazel, and chrysanths.
Thus, the outer layer (exin) of the ivy pollen is rather dry and smooth, but some kind of bumps can be detected. Ivy pollen is also spherical and has a distal pole. The ivy pollen refers to the kind of medium pollen (25-50 microns) and, therefore, can cause pollinosis. If talking about the ratio of the thickness (intine/exine), the intine layer of ice pollen is thicker than the exine. The ivy pollen grains have proximal poles.
In its turn, the Lilly pollen grains have the distal pole. The outer layer (exin) of the Lilly pollen is covered by various sculptures in the form of ridges, bumps, and spikes (as well as the pollen grains of the chrysanths and hazel).
According to the above said, the grains of all four pollen are similar. They all have a complex structure and are covered by various sculptures in the form of ridges, bumps, and spikes, refer to the very small (the size is less than 10 microns) and small (10-25 mm) types of pollen grains and all of them can cause the pollinosis due to their structure and features.
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