Pollination

Pollination
Department Of Botany
Prepared by
Dr. P. B. Cholke
(Assistant Professor in Botany)
Pune District Education Association’s
Anantrao Pawar College ,Pirangut,
Tal-Mulshi, Dist-Pune- 412115

Pollination
Pollination is defined as the transfer
of pollen grains from anther to the
stigma.

Types of self pollination
• 1. Autogamy: transfer of pollen grains from anther to
the stigma of same flower.
• Ex: Pea
• Viola, Oxalis and Commelina produce two types of
flowers:
– Chasmogamous: exposed anther and stigma
– Cleistogamous: closed anther and stigma.
• Cleistogamous flower is invariably autogamous and
assured seed set even in the absence of the pollinator
• 2. Geitenogamy: transfer of pollen grains from anther
to the stigma of another flower of the same plant.
• Ex: Cucurbits.

Types of Cross pollination
• 1. Xenogamy: it is the transfer of pollen grain
from anther of a flower to the stigma of
another flower produced on different plant
belonging to same species.
• Ex Papaya.

• 2. Hybridization:
• it is the transfer of pollen grain from anther of
a flower to the stigma of another flower
produced on different plant belonging to
different variety, sub species or Species.
• Ex: Cotton

• Advantages of self pollination:
1. Since pollen grains are easily available, pollination
rarely fails. It is a sure method of pollination.
2. Flowers do not have to depend on external agencies
like wind, water and animals.
3. Minimum wastage of pollen. Thus, a more economical
method.
4. Pure line progeny can be obtained.
5. There is no wastage of energy for decoration of
flowers to attract insects.
6. There is no chance to obtain unwanted characters.

• Disadvantages of self pollination:
1. Progeny shows less vigor due to continued
self pollination.
2. No possibility of introduction of new
desirable characters
3. Undesirable characters cannot be eliminated.
4. It does not help in evolution.
5. Disease resistant capacity becomes less.

• Advantages of cross pollination:
• Progeny shows enhanced vigor.
• Offsprings are more viable and resistant.
• There is a possibility to get new desirable
characters.
• Yield of crop can be maintained.
• It helps in evolution.
• Undesirable characters of the plant can be
eliminated.
•

• Disadvantages of cross pollination:
• Pollination may fail due to distance barrier.
• Flowers have to totally depend on the external
agencies for pollination.
• More wastage of pollen.
• It may introduce some undesirable characters.

• Floral adaptations for anemophily :
 Pollination carried out by wind is called as anemophily.
 Flowers are small, numerous and inconspicuous
 Stamens possess long filaments and anthers are
versatile
 Pollen grains are smooth, dry and light in weight.
 Flowers bear well exposed stamens so that they can be
easily dispersed by wind currents.
 Pollen grains are produced in large numbers to
compensate their wastage.
 To catch pollen grains, the stigmas become sticky, hairy,
feathery or branched.
 Flowers are devoid of scent, nectar, etc.
• e.g. Grasses, Maize, Jowar, Sugarcane, etc.

• Floral adaptations for hydrophily :
 Pollination carried out by water is called hydrophily.
 Flowers are small, inconspicuous and unisexual.
 Floral parts and pollen grains are unwettable, i.e.
coated with mucilage.
 In plants with submerged female flowers, the pollen
grains have specific gravity equal to or slightly greater
than water.
 In plants with floating female flowers, the pollen-
grains have specific gravity less than that of water.
• Stigma is long and sticky.
• Scent, colour and nectar absent in flowers.
• e.g. Vallisneria, Ceratophyllum

Types
A) Hypohydrophily :
• Pollination that takes place with the help of
water below the water surface in hydrophytes
bearing submerged female flowers is called
hypohydrophily. e.g. Zostera and
Ceratophyllum.
• B) Epihydrophily :
• When pollination occurs on the surface of
water, it is called epihydrophily. e.g. Vallisneria

• In Vallisneria, epihydrophily type of pollination
takes place.
• Vallisneria is a dioecious plant (male and female
flowers are produced on different plants) and
flowers are submerged.
• At the time of maturity, the male flowers are
detached from the male inflorescence and begin
to float on water surface.
• The female flowers have coiled, long pedicel
which undergoes uncoiling at the time of maturity
and reaches the water surface.
• The male flowers surround the female flower
and undergo anthesis due to which pollen grains
are deposited on the stigma of female flower
and cross pollination is achieved.

Floating male flowers
Coiled stalk of
female flower
Fig. Hydrophily e.g. Vallisneria

• Floral adaptations for entomophlly :
Pollination carried out by insects is called as
entomophily (bees are most common agents).
Flowers are large and attractive.
Flowers have attractive bright colors, with
pleasant fragrance and nectar gland.
In some plants, additional modifications are
made to attract insects. e.g. Corona in passion
flower and petalloid bracts in Bougainvillea.
Pollen grains possess spiny or rough outer wall.
Stigma has rough and sticky surface.

• To favour insect pollination, some plants
develop special mechanism e.g. liver
mechanism in Salvia.
• e.g. Jasmine, Rose, Salvia, Bougainvillea.

lever-mechanism or turn-pipe
mechanism In Salvia.
i) In Salvia, flower is bisexual and protandrous, i.e. anthers
mature earlier than stigma.
ii) The two stamens of flower have long bifurcated connective.
iii)Upper branch of connective bears fertile anther lobe, while
lower has sterile anther lobe.
iv)When an insect enters the flower, it pushes the lower sterile
lobes. As a result, the upper fertile anther lobe bends down.
v) The fertile anther lobe comes in contact with back side of
insect body and pollen grains are dusted there.
vi)When the same insect visits another flower with matured
gynoecium, the pollen grains are picked up by the receptive
stigma.
vii) This mechanism is called lever-mechanism or turn-pipe
mechanism.

• Floral adaptations for ornithophily :
 Pollination carried out by birds is called ornithophily.
 Flowers are large with thick and fleshy floral parts.
 Corolla is tubular or funnel shaped.
 Flowers are with bright colours for attracting the birds.
 Flowers lack fragrance as birds have poor sense of
smell.
 Pollen grains are sticky.
 Large amount of sugary nectar produced by the flower
is used as drink by the birds.
• e.g. Callistemon (bottle brush), Bignonia, Butea and
Bombax (silk cotton).
• The commonly pollinating birds are: crow, bulbul,
sunbirds and humming birds.

• Floral adaptations for Chiropterophily :
• a) Pollination takes place with the help of bats.
• b) Flowers are large, stout enough so that bats
can hold on to the flowers.
• c) Chiropterophilous plants are nocturnal, i.e.
open their flowers during night time.
• d) Flowers emit rotten fruits like fermenting
fruity odour.
• e) Flowers have large number of stamens to
produce a considerably large quantity of pollen
grains.
• e.g. Anthocephallus (Kadamb),
Adansonia (Baobab tree), Bauhinia

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