Pollination, Pollination types, Chasmogamous, Cleistogamous flowers, Pollination by air, water and animals, Out breeding devices

1. Pollination
• Chasmogamous
• Cleistogamous flowers

2. • Pollination: Transfer of pollen grains (shed
from the anther) to the stigma of a pistil is
termed pollination.
• Kinds of Pollination :
• 1.Autogamy
• 2. Geitonogamy
• 3.Xenogamy

3. Autogamy:
• Transfer of pollen grains from the anther to
the stigma of the same flower.
• Complete autogamy is rare

4. • Autogamy requires synchrony in pollen release
and stigma receptivity.
• The anthers and the stigma should lie close to
each other so that self-pollination can occur.
Pea plants
are naturally self-pollinating..

5. Viola (common pansy), Oxalis, and Commelina
• Chasmogamous: Flowers which are similar to
flowers of other species with exposed anthers
and stigma
• Cleistogamous: flowers which do not open at
all. In such flowers the anthers and stigma lie
close to each other.

6. Commelina
Chasmogamous
Cleistogamous
Underground
flowers

7. In Cleistogamous flowers
no chance of cross-pollen.
Pea flowers produce assured seed sets.
Pollinators not require (Pollinating agent not
require).
Advantageous: 100% seed set formation.
Disadvantageous: Offspring's produce have
limited genetic diversity.

8. • Geitonogamy: Transfer of pollen grains from the
anther to the stigma of another flower of the
same plant.
• Geitonogamy: is functionally cross-pollination
involving a pollinating agent.
• Geitonogamy: genetically it is similar to
autogamy.

9. Xenogamy
Xenogamy: Transfer of pollen grains from
anther to the stigma of a different plant.
Xenogamy: brings genetically different
types of pollen grains to the stigma.
Xenogamy

10. Agents of Pollination
ABIOTIC BIOTIC
WIND
&
WATER
ANIMALS
INSECTS
BIRDS
Etc.
• Pollen grains coming in contact with the stigma is a chance
factor in both wind and water pollination.

11. Pollination by wind (Anemophily)
• Pollination by wind is more common
amongst abiotic pollinations..
Wind pollination requires:
 Pollen grains are light and non-sticky.
 Flowers possess well-exposed stamens.
 large often-feathery stigma to easily trap air-
borne pollen grains.

12. Wind pollinated flowers
• Wind pollinated flowers often have a single
ovule in each ovary.
• Numerous flowers packed into an
inflorescence.
• .
A wind-pollinated plant showing compact
inflorecence and wellexposed stamens

13. Wind-pollination is quite common in
grasses
• Example: The corn cob :
the tassels you see are
nothing but the stigma
and style…
• Wind pollinated flowers
are not colourful and do
not produce nectar.

14. Pollination by Water (Hydrophily)
• Pollination by water is quite rare .
• Only 30 genera (genus), mostly monocotyledons.
• In lower plants like Algae, Bryophytes and
Pteridophytes water is a medium to transport male
gametes.

15. Water pollinated plants
• Vallisneria and Hydrilla which grow in fresh
water.
• Sea-grasses such as Zostera.
• Majority of aquatic plants such as water
hyacinth and water lily are pollinated by
insects or or wind.

16. Pollination in Vallisneria (Epihydrophily)

17.  In Vallisneria, the female flower reach
the surface of water by the long stalk.
 The male flowers or pollen grains are
released on to the surface of water.
 They are carried passively by water
currents and reach the female flowers.

18. Pollination in sea grasses (Hypohydrophily)
• In sea grasses, female flowers remain
submerged in water and the pollen
grains are released inside the water.
• Pollen grains in many such species are
long, ribbon like.

19. • In most of the water-pollinated species, pollen
grains are protected from wetting by a
mucilaginous covering.
• Water pollinated flowers are not colourful and
do not produce nectar.

20. Pollination by animals: Zoophily
• Pollen is transferred by Bees, butterflies,
beetles, wasp, ants, moths, birds.
• Even larger animals such as some primates
(lemurs), arboreal (tree-dwelling), rodents, or
even reptiles (lizard).
• The plants pollinated by animals are very large
attractive and nectar…….

21. Entomophily: The pollination with the help
of insects.
Most of insect pollination (80 %) only by
Honey bees..
Example: Sunflower, Lemon, cotton ,
Tobacco

22. • Majority of insect-pollinated flowers are large,
colourful, fragrant and rich in nectar.
• Pollen grain is sticky.

23. The flowers pollinated by flies and beetles secrete foul
odours to attract these animals.
• To sustain animal visits, the flowers have to provide
rewards to the animals.
• Nectar and pollen grains are the usual floral rewards.

24. Flowers of animal pollinated plants are adapted
for a particular species of animal.

25. • Some flowers provided safe places to lay eggs;
of insects.
• Example: Tallest flower of Amorphophallus
(the flower itself is about 6 feet in height).

26. Moth and the plant Yucca
• Moth and the plant – cannot complete their
life cycles without each other.
• The moth deposits its eggs in the locule of the
ovary and the flower, in turn, gets pollinated
by the moth.

27. Fig fruit and the wasp

28. Ornithophily
• Pollination by birds.
Eg: Silk cotton tree

29. Ophiophily
• Pollination by snakes.
• Example: Santalum (Sandal).

30. Chiropterophily:
Pollination by bats.
Example: Sausage tree

31. Malacophily
Pollination by snails.
Example:
Chrysanthemum

32. Pollination by Termites and ants.
Example: Rubiaceae (Coffea)
Myrmecophily:

33. • Many insects may consume pollen or the
nectar without bringing about pollination.
• Such floral visitors are referred to as
pollen/nectar robbers.

34. Outbreeding Devices :
Majority of flowering plants produce
hermaphrodite flowers.
Continued self-pollination result in inbreeding
depression..(reduced biological fitness)..

35. Flowering plants have developed many devices to
discourage self pollination
1.Pollen release and stigma receptivity are not
synchronised (Dichogamy).
The pollen is
released before the stigma
becomes receptive..
The stigma becomes receptive
much before
the release of pollen.
Protandry Protogyny

36. 2.The anther and stigma are placed
at different positions…
So that the pollen cannot
come in contact with the
stigma of the same flower.
Herkogamy:
In some
plants
morphological
barriers
between
anther and
stigma,
Prevents
autogamy

37. • 3).The third device to prevent inbreeding is self-
incompatibility.
• This is a genetic mechanism its prevents self-
pollen by inhibiting pollen germination or pollen
tube growth in the pistil.

38. 4). Another device to
prevent self-pollination is the production of unisexual flowers.
• Dicliny (Unisexuality): Presence of unisexual flowers..
 If both male and female flowers present on same plant. Eg:
Castor, Cucurbits, Maize..
 It prevents autogamy but not Geitonogamy..
 If male and female flowers are present on different plants. Eg:
Papaya, Date palm..
 It prevent both autogamy and geitonogamy..

39. Heterostyly and Heteroanthy
DiMorphic

40. Pollen-pistil
Interaction
• The events–from pollen deposition on the stigma
until pollen tubes enter the ovule are together
referred to as pollen-pistil interaction…

41. • The pistil has the ability to recognise the pollen,
whether it is of the right type (compatible) or of
the wrong type (incompatible).
• If it is of the right type, the pistil accepts the
pollen and promotes post-pollination events that
leads to fertilisation…

42. The acceptance or rejection is the
result of a continuous dialogue
between pollen grain and the pistil. ..
This dialogue is mediated by
chemical components of the
pollen interacting with those
of the pistil.

43. • Compatible pollen grain
germinates on the stigma to
produce a pollen tube through
one of the germ pores…
• Pollen tube grows through the
tissues of the stigma and style
and reaches the ovary…

44. • Pollen grains are shed at two-celled condition.
• In such plants, the generative cell divides and
forms the two male gametes during the growth of
pollen tube in the stigma…

45. • Pollen tube, after reaching the ovary, enters the
ovule through the micropyle
• and then enters one of the synergids through
the filiform apparatus..

46. Porogamy: The pollen enters into the ovule
through Micropyle. Eg: Most angiosperms.
Chalazogamy: Chalaza. Eg: Casuarina.
Mesogamy: Integuments. Eg: Cucurbita.

48. Easily study pollen germination
• Sprinkle pollen from
flowers such as pea,
chickpea, Crotalaria,
and vinca rosa on a
glass slide containing a
drop of sugar solution..
10 %
Sugar
solution
15–30 minutes..

49. Dr. HarinathaReddy Aswartha
Assistant professor
Department of Microbiology
biohari14@gmail.com