This document discusses pollination, which is the transfer of pollen grains from the anther to the stigma of a flower. It requires an external agent such as wind, water, animals, or contact between plants. There are different types of pollination including self-pollination (autogamy and geitonogamy) and cross-pollination (xenogamy). Cross-pollination introduces genetic variation and is aided by agents like wind (anemophily), water (hydrophily), or insects (entomophily). Features of the flower help ensure cross-pollination occurs, such as dichogamy or herkogamy. Cross-pollination provides advantages like increased

1. Pollination
Nidhi Arya
PGT Biology (JNV Sonipat)

2. Parts of flower

3. What is
pollination?
The transfer of pollen grains
from the anther to the stigma
of a flower.
Pollen grains are immobile.
They cannot reach the stigma
by themselves.
An external agent is required
for this. It can be wind, water,
animal, gravity or growth
contact.

5. Two Content Layout with Table
• Autogamy
• Geitonogamy
• Xenogamy
Plant Pollen Stigma
Plant 1 Flower
A(P1FA)
P1FA P1FA
Plant 1 Flower
B(P1FB)
P1FA P1FB
Plant 2 Flower
C(P2FC)
P1FA P2FC

6. Types of
pollination
• .
• .

8. Self pollination
Autogamy
It is a type of self pollination in which an
intersexual
or perfect flower is pollinated by its own
pollen.
Autogamy occurs by 2 methods :
Homogamy :The anthers and
stigmas of chasmogamous or open
flowers are brought together by
growth, bending or folding.
Cleistogamy :In cleistogamous flowers, the
anthers dehisce inside closed flowers. Growth
of style brings the pollen grains in contact
with stigma. Pollination and seed set are
assured. Pollinators are not required.
Gietonogamy
• It is a type of pollination in which
pollen grains of one flower are
transferred to the stigma of another
flower belonging to either the same
plant or genetically similar plant.
• In geitonogamy, the flowers often
show modifications similar to ones
found in xenogamy or cross
pollination.

9. Advantages and disadvantages
• Advantages of self Pollination:
1.It maintains the parental
characters or purity of the race
indefinitely.
2.Self pollination is used to
maintain pure lines for
hybridisation experiments.
3.The plant does not need to
produce large number of pollen
grains.
4.Flowers do not develop devices for
attracting insect pollinators.
Disadvantages of Self Pollination:
1.New useful characters are seldom
introduced.
2.Vigour and vitality of the race
decreases with prolonged self
pollination.
3.Immunity to diseases decreases.
4.Adaptability to changed
environment are reduced.

10. CROSS POLLINATION
(XENOGAMY/ALLOGAMY)
 Cross pollination is
the transfer of pollen
grains from the
anther of one flower
to the stigma of a
genetically different
flower.
 Cross pollination is
performed with the
help of an external
agency

12. Anemophily
 It is a mode of cross
pollination or transfer
of pollen grains
through the agency of
wind.
 e.g., Coconut Palm,
Date Palm, Maize,
many grasses,
Cannabis.
• Pollens are produced
in very large numbers

13. Hydrophily
 It is the mode of pollination
or transfer of pollen grains
through the agency of
water.
 Eg. Zoostera , vallisneria.
Characters:
 Flowers are small and
inconspicuous.
 Nectar and odour are
absent.
 Pollen grains are light and
unwettable due to presence
of mucliage cover.
 Stigma is long, sticky but
unwettable.

14. Types of hydrophily
Epihydrophily Hypohydrophily

15. Entomophily
 Pollen grains are transferred to a
mature through the agency of insects
like moths, butterflies, wasps, bees,
beetles, etc.
 Example: Rose, Jasmine
Characters :
 They are showy or brightly coloured.
 Most insect pollinated flowers
have a landing platform.
 The pollen grains are spiny, heavy
and surrounded by a yellow oily
sticky substance called pollenkit.
 Stigmas are often inserted and sticky.
 Some flowers provide safe place to
insects for laying eggs, e.g., Yucca.

16. METHODS TO ENSURE CROSS POLLINATION
Dichogamy :
 Anthers and stigmas mature at
different times in a bisexual flower so
as to prevent self pollination.
- Protandry Anthers mature earlier
than stigma of the same flower. Their
pollen grains become available to
stigmas of the older flowers, e.g.,
Sunflower, Salvia,
- Protogyny
Stigmas mature earlier so that they get
pollinated before the anthers of the same
flower develop pollen grains, e.g.,
Mirabilis jalapa (Four O’Clock), Gloriosa,
Plantago.

17.  Herkogamy :
 In some bisexual flowers the
structure of male & female sex
organs itself prove a barrier to
self pollination.
 Self Sterility
(Self Incompatibility):
 Pollen grains of a flower do not
germinate on the stigma of the
same flower due to presence of
similar self sterile gene (S,S3 in
pistil and S1 or S3 in pollen
grain), e.g., Tobacco, Potato,
Crucifers.

18. Artificial Pollination
 This technique is used for the purpose of
• Hybridization.
 It involves pollination of desired female parents with pollen from
the desired male parent, taking all precautions to prevent
contamination of stigma with undesired pollen.
 In unisexual plants the procedure is simple but its complicated in
bisexual ones.
 2 processes that takes place in bisexual flower :
- Emasculation
- Bagging

20. Significance of cross pollination
Advantages
Cross pollination introduces
genetic re- combinations and
hence variations in the progeny.
Cross pollination
increases the adaptability of
the offspring towards
changes in the
environment.
It makes the organisms
better fitted in the struggle for
existence.
The plants produced through
cross pollination are more
resistant to diseases.
Disadvantages
A factor of chance is always
involved in cross .pollination.
It is less economical.
Some undesirable characters
may creep in the race.
The very good characters of the
race are likely to be spoiled.

21. Thankyou
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