Pollen

The pollen (of the Greek blade: Flour or Poussière) constitutes, at the higher plants, male element fertilizing Fleur: they are tiny grains of more or less ovoid form of a few tens of Micromètre S of diameter, initially contained in the Anthère at the end of the cheesecloth S.

Like the ovule, the grain of pollen is not a Gamète but a Gamétophyte, a producer of gamète.

The counterpart of the grain of pollen at the lower plants (Alga S, foam S, Prothalle of the Fern S) is the male Gamétophyte.

It corresponds to the phase Haploïde of the development of the plant.

Composition

The grain of pollen is a spore containing the male Gamétophyte. It appears at the présepermaphytes, which thus do not release spores since they remain on the Sporophyte. It usually made up of two cell S not is partitioned and comprises two haploid cores, of which one larger is the vegetative core and the other the generative or reproductive core. It is locked up in a resistant envelope, the Exine, which comprise apertures, points of less resistance which will allow the emission of the pollen Tube intended to fertilize the ovule.

Pollen contains a strong proportion of Protéine S (from 16 to 40%) containing all the amino-acid known. It also contains many Vitamine S, in particular Vitamine C and Vitamine PP. Pollen is used as food with the Abeille S of which it is the only source of proteins. It enters the composition of the royal Jello. It is always present, in minor amount, in the Miel, and makes it possible to identify its botanical origins. The Apiculture calls upon the melissopalynology which is the science of honey and pollen.

Pollination

To germinate, the grain of pollen must land on the Stigmate of a female Fleur. transport is generally done by the Vent or the Insecte S: it is the Pollinisation.

Allergies

The presence of grains of pollens in the atmosphere (its diffusion by the wind is the Anémogamie) which we breathe is very important in spring and causes Allergie S at the sensitive people.

Palynology

The Palynologie is the scientific study of pollens. A pollen is often specific of a vegetable group ( family, kind), sometimes even of the Espèce: it is possible to identify a plant specie by the observation of its pollen. The characters observed are the size (from 2,5 to 200 micrometers), the general form and those of the exine: the stratification, sculptures and granulations of surface, the number the form and the provision of the apertures.

The applications of the Palynologie are numerous:

  • palynology brings useful elements in the study of vegetable Systématique;
  • the Paléopalynologie is the study of pollens Fossile S, and makes it possible to give information on the Climat and the Végétation during the quaternary era;
  • the Aéropalynologie, which consists in analyzing the presence in the air of various types of pollens has applications in Médecine (allergic pathologies) and in Agronomie (Pollinisation);
  • the melissopalynology is the study of pollens present in the Miel, which makes it possible to detect the mixtures and the frauds.
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