Wind-Fertilization of plants

Egg cell production in plants requires
fertilization process,during which pollens,
as the male reproductive cells,meet and
unite with ovule as female reproductive
cells this process takes place in the flower
( the reproductive organ in plants ).

A perfect flower has both stamens ) pollen
producing organ ( and carpels ) egg producing
organ (. During the first phase in the
fertilization of an egg,pollination,pollen
is transmited onto the stigma of a carpel.
This transfer is carried out in four ways :
1- Insects,most plants depend on the activity
of such insects as honey bee for their
fertilization.While making use of nectar and
pollens of flowers as food,sticky pollens
adher to their body parts.When flying from
flower to flower they transfer these pollen
grains to the stigma of the flowers visited;
apple,pear,almond and peach trees are among
plants which depend on insects for their
fertilization.

2- Weight,in some plants stamens are located
on carpels in a way that their pollen grains,
as a result of their weight,fall onto the
stigma hence,pollination takes place.

3- Human pollination,in some plants like date
palm in which the flowers are not completed
in themselves that is,their male and female
sexual organs are located on two different
trees,for higher yield,pollination is carried
out by human. In this method pollen bearing
flowers of the male tree are cut and shaken
over the flowers of the female tree . This
method is also done for other plants such as
Lebnaneese red apple ) red delicious ( when
economical.

4 - Wind,in some kinds of plants pollination
is carried out by wind ;the pollen grains of
these plants are readily distributed by wind
because they are light and dry and have
a special shape.Flowers of such plants do not
generally have scents,nor do they have very
attractive colors,their stigmas are usually
big and leaf-like so that they can receive
a great number of pollen grains . Pollen
production in these kinds of flowers is
extremely high , so that all flowers would
certainly receive pollens.For example,walnut,
hazelnut and pistachio trees and among crops
oat,and corn,belong to this group.It is worth
saying that plants which need wind and
insects for their pollination are generally
cross polination.

Of course wind is not always useful for
pollination especially for insect-pollinated
ones.Because insects,mainly bees,decrease
their activity in wind,and strong winds also
cause mechanical harms to flowers,make their
stigmas dry and create a condition which is
not suitable for receiving pollens.