Download Parts of an insect pollinated Flower.

Parts of an insect pollinated Flower.
All Parts of the Flower arise from
flower stalk.
Perianth=Petals+Sepals
Gynaecium=Ovary,Style and
Stigma
Androecium=Stamen
(Anther+Filament)
Sepals:
Parts of a Flower.
Are usually green and occasionally
coloured to attract insects.
Sepals encloses and protects flower
buds.
Petals:
are large and brightly coloured in
insect pollinated flowers to attract
insects.
The dark lines on the petals help direct
the insects to the nectar source and thus
bring them into contact with the stamens
and stigma.
Petals are usually shorter than
anther or absent in wind pollinated
flower.
Gynaecium: Female Part of a flower
Stigma: receives pollen grain(s) during pollination.
Style: positions stigma in a suitable position in the flower to receive
pollen.
Ovary: is the swollen, hollow base containing one or more ovules.
Ovules: are the structures in which, embryo sac develops and which, after
fertilization, becomes seeds.
Androecium: Male part of a flower
Stamen consists of Filament and Anther.
Anther: is where pollen is made and it brake opens to release pollen.
Filament: contains vascular bundles (Xylem & Phloem) that supplies food and
water to the Anther.
Pollination:
The transfer of pollen from an Anther
to a stigma is called pollination.
Types of pollination:
Self Pollination
Cross pollination

Self Pollination:
Transfer of pollen from an Anther to a
stigma of the same flower or a flower
on the same plant is called self
pollination.
Examples: Chickweed and Groundsel
Advantages and disadvantages of self-pollination:
Advantages
Disadvantage
Self-pollination leading to self-fertilization has
the advantage of greater reliability, particularly
where members of the species are uncommon
and are separated by large distance.
Self-pollination is
the extreme form of
inbreeding and can
result in less
vigorous offsprings,
to fight harsh or
change in
environment.
It is also useful in harsh climate where insects
are less common, such as high up on the
mountains.
Self Pollination:
Few plants avoid self pollination:
Anther matures first and stigma
becomes receptive at later stages.
Eg; Dandelion.
Self Sterility: inhibition of pollen
penetration of the stigma.
Eg; Primrose.
Position: Stigma positioned above
Anthers.
Cross
Pollination:
Transfer of pollen from
the Anther of one
flower to the stigma of
another flower on a
different plant is called
Cross pollination.
Examples: Rose and
Jasmine
Advantages and disadvantages of Cross-pollination:
Advantages
Disadvantage
Cross-pollination is a form of ‘out
breeding, and offers greater
amount of genetic variation
helping them with greater
chances of survival of the
offsprings, against change in
environment.
Cross-pollination is a disadvantage
particularly where members of the species
are uncommon and are separated by large
distance.
Pollens are to be produced in large
quantities and its too much wastage of
pollens.
Agents of Pollination:
Wind
Insects & Small Birds
Wind Pollination:
Insect Pollination:
Bees/Butterfly
Pollination: Bright
color, nectaries, scent.
They sip nectar, get pollen on
coats,
transfer pollen from flower to
flower
Bird Pollination:
Birds lap up the nectar with
their tongue, bird-pollinated
flowers produce nectar that
is more fluid Pollen does not
readily stick to the bill, but
does to the feathers.
Bat Pollination:
Bats are usually active
at night, so flowers they
pollinate are often
white.
Fly Pollination:
Some flowers look and
smell like dung or rotten
meat. Dung and carrion
flies mistakenly lay their
eggs on the flower and in
the process collect and
pass pollen
Why animal pollinators "service" flowering plants
A. Rewards for the pollinator- food
 The most common attraction is food, the nectar (a sugar solution).
B. Pollen (high in protein)
 Beetles eat pollen directly
 Bees use pollen to make bee bread (mixture of pollen and nectar;
used to feed larvae)
 Some plants (roses, peonies, and poppies) rely on pollen as a
reward and don't produce any nectar
 Some flowers produce two kinds of pollen (normal pollen and
sterile, tasty pollen for insects)
Adaptations of wind-pollinated
flowers:
Adaptations of insect-pollinated
flowers:
The flowers are quite small with leaf like
bracts, rather than petals.
Most of the insect-pollinated flowers have
bright coloured petals, to attract a variety of
insects.
The anther and stigma are not enclosed by
bracts. Instead large branched stigma
hanging outside flower to trap pollen.
Small Stigma, sticky to hold pollen and
enclosed within flower.
Wind-pollination flowers produce large
quantities of pollen, which can be carried by
wind easily.
Less pollen produced.
Pollen Grains relatively light, small, dry and
often contain smooth walls.
Pollen grains are relatively heavy and large.
Spiny walls and stickiness help attachment to
insect body.
Anthers are not rigidly attached to filament,
which can be shaken easily by wind for
pollen dispersal.
Anthers are fixed at their bases to the filament
and often immovable.
Not Scented
Scented (mostly)
No Nectar
Produce Nectar to attract insects.
The dark lines on the petals help direct the
insects to the nectar source and thus bring
them into contact with the stamens and
stigma.
Pollen of a wind
pollinated flower
Pollen of an insect
pollinated flower
Pollination
Cells divide (Meiosis) and increase
in number, within the Anther.
Walls of the Anther dries and
tension is created within the Anther,
which eventually burst, to release
pollen
Pollination & Pollen tube formation
Fertilization:
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The process of fertilization is initiated with the transfer of pollen to
the stigma of the same species.
The pollen starts germinating by absorbing sucrose solution,
secreted by the epidermal cells of the stigma.
Exine (outer wall) that brakes and the intine (Cell membrane)
protrudes and grows out through the style (pollen tube).
Pollen tube is directed towards the ovary by certain chemicals.
The nucleus of the pollen divides into two.
The pollen tube enters the ovary through a small hole called
‘micropyle’. One nucleus combines with the nucleus of egg cell to
form diploid zygote. The second nucleus combines with two polar
bodies forming a triploid (3n), that develops into endosperm, a food
storing tissue.
The fertilized egg cell develops into an embryo. The ovary becomes
the fruit and the ovule becomes a seed - from which (once dispersed)
the offspring plant will grow.
Each ovule in an ovary needs to be fertilized by a separate pollen
grain.
Although pollination is must before fertilization, pollination does not
necessarily result in fertilization.
Fertilization:
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The process of fertilization is initiated with the transfer of pollen to
the stigma of the same species.
The pollen starts germinating by absorbing sucrose solution,
secreted by the epidermal cells of the stigma.
Exine (outer wall) that brakes and the intine (Cell membrane)
protrudes and grows out through the style (pollen tube).
Pollen tube is directed towards the ovary by certain chemicals.
The pollen tube enters the ovary through a small hole called
‘micropyle’. Here it combines with the nucleus of egg cell to form
diploid zygote.
The fertilized egg cell develops into an embryo. The ovary becomes
the fruit and the ovule becomes a seed - from which (once dispersed)
the offspring plant will grow.
Each ovule in an ovary needs to be fertilized by a separate pollen
grain.
Although pollination is must before fertilization, pollination does not
necessarily result in fertilization.
Seed and Fruit Development
After fertilization,
the petals and
sepals fall off
flower
Ovary “ripens”
into a fruit
The ovule
develops into a
seed
Seed Dispersal MechanismsAllow plants to colonize new areas and avoid shade
of parent plant
Wind Dispersal - Flight mechanisms,
like parachutes, wings, etc.
Ex. Dandelion, maples, birch
Animal Dispersal - Fleshy fruits which
animals eat, drop undigested seeds in
feces or burrs which stick to
animals’ coats
Gravity Dispersal Heavy nuts fall to
ground and roll
ex. acorns
Water Dispersal - Plants
near water create floating
fruits
ex. coconuts
Monocot Seed Germination
Monocots grow
straight up with
coleoptile sheath
covering shoot
One embryonic leaf
Seed remains
underground
Dicot Seed Germination
Curved stem comes
up out of soil
Two embryonic
leaves
Seed goes above soil
Parts of the Embryo
Epicotyl - Grows into
the leaves of the plant
Hypocotyl - Becomes
the stem
Radicle - Becomes
the root