What is pollen?

Pollen is the male gametophyte of higher plants, necessary for pollination and insemination of the female flower to induce seed production. To some extent, is is comparable to the sperma of animals, although this comparison matches only the functionality.

How is a pollen grain constructed?
The size of a pollen grain (which consists of at least two cells) is usually around 20-30 thousandth millimetres microns). This is about one third of the width of a human hair. Therefore you can hardly see a single pollen grain with the unarmed eye.

On its surface, there are lots of different, very specific proteins. They act as an identification card to exchange information with the female part of the plant. As these proteins are instantly water soluble, they are also able to penetrate the mucous membranes and cause specific reactions from the immuno system.

why is pollen in the air?
Most plant species are insect-pollinated, but a number of plants deliver their pollen to the wind.
Wind pollinated plants need a much higher pollen production to ensure pollination. Preferably these pollen, which become airborne, are the ones which cause allergies. However, not all the pollen types we can find in considerable amounts in the air do cause allergies, as for instance pine or fir pollen, or pollen of the stinging nettle, which are the most abundant airborne pollen in many regions. The main allergenic pollen are produced by

l   grasses

l   trees of the birch tribe (which are alder, hazel, hornbeam, beech, oak and sweet chestnut

l   wind pollinated composites (mugwort, ragweed)

l   olive tree

l   wall pellitory, and

l   trees of the cypress and related families

Reference information: www.aaaai.org, www.allergy.hk

The information aims to provide educational purpose only. Anyone reading it should consult physician before considering treatment and should not rely on the information above.