PALYNOLOGY (under construction)
grains may be in the solitary form or in groups of two or more.
According to the different types of grouping (clustering) are distinguished:
ss, solitary pollen grain belonging to a tetrad or polyad: pollen unity composed of 8-10-12-16-24-32 pollen grains. which only rarely at the single state is released to the atmosphere
-Pseudomonad or criptotetrad, lonely grain, equivalent to a tetrad where three of the four units have not been developed.
2. pollen grains into groups, include pollen grouped into 2, 4, 8, 16, units etc..
- dyad: unit formed by two grains of the same size. The four grains of the tetrad are emitted into the atmosphere in groups of two. The dyad is generally not widespread: it is occasionally found in Gymnosperms, it is rare in Angiosperms. while in Monocotyledones is only represented.
- tetrad: unit formed by four grains mostly of the same size, the four granules originating from the mother cell’s division are emitted into the atmosphere together. The space arrangement of individual elements composing the tetrads can be:
a) uniplanar when individual granules are on the same floor. The shape can be tetragonal, square and rhomboidal if each unit, of the tetrad, is more or less in contact with all the others.)
b) multiplanar when individual granules are located on different plane. The form, which results when the two pairs are arranged at right angles between them, is called decussata, otherwise when units are located at the vertices of a tetrahedron is called tetrahedral.
pollen characteristics to possess two endowed poles of equal or different features....
is the pollen characteristic to possess two endowed poles of equal or different features. A pollen grain is considered like a globe with two poles and the equator and its polarity is defined in the stadium of meiotic tetrad. The polarity is considered absolute if it derives from the direct observation of the single pollen grains orientation in the tetrad. In every pollen grain is possible to distinguish two areas:
pollen: regroups the pollens with a distinct polarity that is recognizable. They are pollen grains with equatorial or polar apertures. The polar pollen can be distinguished in three types:
pollen: it is the grain in which the two poles are equal and the equatorial plane divides the pollen in two equal parts.
pollen grain in which the two polar areas are not quite the same. The one can be more or less convex than the other or even flat....
pollen: it is the grain in which the two polar areas are not completely equal.
the two polar areas have a different shape....
pollen (AnisopolarAnisopolarDefinition: pollen grain with different poles....
pollen): it is the grain in which the two areas have a different shape (e.g. one is with apertures and the other without)
(POLLEN) – pollen grain without a distinct polarity....
pollen: it is a grain without an apparent polarity, because the poles are not recognizable. It is a spherical and inaperturate pollen or with spread apertures over the entire surface of the granule.
(POLLEN) - pollen grains with a visible polarity....
plane includes the polar axis and passes through the poles of the granule (polar pollens),
- Equatorial plane includes the equatorial diameter (polar pollens)
- Polar axisPolar axisDefinition:
imaginary line connecting the two poles....
passes through the poles and it is included in the polar plane (polar pollens)
- Equatorial axisEquatorial axisDefinition:
axis perpendicular to the polar axis, lying in the equatorial plane....
is the line passing through the equatorial plane and the center of the pollen
opening to allow pollen tube germination. Zone of pollen grain surface in which the exine thins or completely lacks....
grains usually have apertures just in some cases they haven’t (inaperturate). The apertures are areas in which the intine is thickened and the exine is thinner (respect to the rest of the wall) or missing. The apertures are the area of the normal output of the pollen tube at the time of germination. Traditional palynology usually characterizes apertures by their number (numerus), position (positio) and shape (caracter). The number can vary from N1 to N7: N1 is attributed to pollens with one aperture, N7 is for pollens with several apertures (>6). InaperturateInaperturateDefinition: pollen grain without apertures....
pollens are marked with NO. The apertures have a precise location compared to the equator and the poles of the granule itself, when this is not defined pollen is called anomoaperturate. The possible positions are three:
(POLLEN) - pollen grains with a visible polarity....
: the apertures are at the poles or in the immediate vicinity.
- Equatorial: the apertures are at the equator or in its proximity,
apertures position distributed over the whole granule surface....
: the apertures are spread in a more or less regular manneron all the granule surface.
s are also characterized by their shape (C=caracter). There are three apertures types: elongated, like a sulcus; circular like a pore; ring or belt.
If the edges of the apertures are not clear, are indicated by introducing the syllable –oid (p.e. colpoid, poroid). In C0 the aperture is indistinct, while in C1 it is represented by a more or less regular area. In C2 the aperture is divided into three anastomosed arms. C3 is the term used for sulcus-shaped apertures and C4 for pore-shaped ones (porus). C5 is used for colporate pollens. Lastly there are he C6 pororate pollens which have either a colpus or a pore externally and a circular oval part set in their