@sexual reproduction in flowering plants

1. @Sexual Reproduction in
flowering plants

2. Flowering plant
• Flowering plants are the dominant plant form
on land and they reproduce by sexual means.
Often their most distinguishing feature is
their reproductive organs, commonly called
flowers.
• Flowering plants, also called angiosperms, use a
sexual mode of reproduction. Reproduction in
plants mainly revolves around the flower, which
has both the male and the female gametes. All
the parts of a flower aid in the process of
reproduction, although some of them are
sterile. To understand about sexual
reproduction we need to look through its
reproductive organ flower.

3. Flower {reproductive organ}
• DIAGRAM 1 :- Stigma
Style
Ovary
Anther
Filament

4. Flower diagram 2 :-

5. DIAGRAM 3

6. FLOWER’S PARTS AND
FUNCTIONS
A flower consists of the following parts-
Calyx: Commonly known as sepals, these leaf like
structures protects the flower when it develops from a
bud.
Corolla: These are the bright and colourful petals of
the flower which attract insects and birds, who are the
agents of pollination.
Androecium: It is the male reproductive flower parts,
also known as stamens. Stamens consist of two parts:
Anther: This is a four lobed sac-like structure
responsible for pollen formation.
Filaments: These thread-like structures are attached
to the anther and they keep the anther in place.

7. • Gynoecium: Also called carpels or pistils,
these are the female reproductive parts of
the flower. Carpels are made up of three
parts:
• Ovary: The ovary is a chamber where ovules
(eggs) are stored, waiting for fertilization.
• Stigma: It is attached to the top of the
carpel, where the pollens from other flowers
land.
• Style: It is a tubular structure that connects
the ovary and the stigma. It is responsible for
the transportation of pollens from the stigma
to the ovary and holding the stigma in place.

8. PROCESS OF SEXUAL REPRODUCTION

9. PROCESS OF SEXUAL REPRODUCTION

10. • Sexual reproduction in flowering plants involvesSexual reproduction in flowering plants involves
the production of male and female the production of male and female gametesgametes, the, the
transfer of the male gametes to the femaletransfer of the male gametes to the female
ovules in a process called ovules in a process called pollinationpollination. After. After
pollination occurs, pollination occurs, fertilizationfertilization happens and the happens and the
ovules grow into seeds within a ovules grow into seeds within a fruitfruit. After the. After the
seeds are ready for seeds are ready for dispersaldispersal, the fruit ripens, the fruit ripens
and by various means the seeds are freed fromand by various means the seeds are freed from
the fruit and after varying amounts of time andthe fruit and after varying amounts of time and
under specific conditions the seeds under specific conditions the seeds germinategerminate
and grow into the next generation. and grow into the next generation.

11. • The The antheranther produces male produces male gametophytesgametophytes
which are which are pollen grainspollen grains, which attach to, which attach to
the stigma on top of a the stigma on top of a carpelcarpel, in which the, in which the
female gametophytes (inside ovules) arefemale gametophytes (inside ovules) are
located. After the pollen tube growslocated. After the pollen tube grows
through the carpel's style, the sperm fromthrough the carpel's style, the sperm from
the pollen grain migrate into the ovule tothe pollen grain migrate into the ovule to
fertilize the egg cell and central cell withinfertilize the egg cell and central cell within
the female gametophyte in a processthe female gametophyte in a process
termed termed double fertilizationdouble fertilization..

12. • The resulting zygote develops into anThe resulting zygote develops into an
embryo, while the triploid endosperm (oneembryo, while the triploid endosperm (one
sperm cell plus a binucleate female cell) andsperm cell plus a binucleate female cell) and
female tissues of the ovule give rise to thefemale tissues of the ovule give rise to the
surrounding tissues in the developing seed.surrounding tissues in the developing seed.
The ovary, which produced the femaleThe ovary, which produced the female
gametophyte(s), then grows into a gametophyte(s), then grows into a fruitfruit,,
which surrounds the seed(s). Plants maywhich surrounds the seed(s). Plants may
either either self-pollinateself-pollinate or or cross-pollinatecross-pollinate.

13. Pollination
• Pollination is the process where mature pollens
are transferred to the stigma for the purpose
of sexual reproduction in flowering plants. It
can happen in two ways-
• Cross-Pollination: If pollens from the flower of
one plant lands on the stigma of another flower
of a different plant, it is called Cross-pollination
or Birds. Bees, insect and the wind are some of
the agents of cross-pollination
• Self-Pollination: If the pollen of a flower is
transferred to its own ovary, it is known as Self-
pollination, or fertilization.

14. Self pollination

15. • Self-pollination is when pollen from the same
plant arrives at the stigma of a flower (in
flowering plants) or at the ovule (in
Gymnosperms). There are two types of self-
pollination: In autogamy, pollen is transferred
to the stigma of the same flower. In
geitonogamy, pollen is transferred from the
anther of one flower to the stigma of another
flower on the same flowering plant, or from
microsporangium to ovule within a single (
monoecious) Gymnosperm. Some plants have
mechanisms that ensure autogamy, such as
flowers that do not open (cleistogamy), or

16. • Occurrence
• Few plants self-pollinate without the aid of
pollen vectors (such as wind or insects). The
mechanism is seen most often in some
legumes such as peanuts. In another legume,
soybeans, the flowers open and remain
receptive to insect cross pollination during
the day. If this is not accomplished, the
flowers self-pollinate as they are closing.
Among other plants that can self-pollinate
are many kinds of orchids, peas, sunflowers
and tridax.

17. • Most of the self-pollinating plants have small,
relatively inconspicuous flowers that shed pollen
directly onto the stigma, sometimes even before
the bud opens. Self-pollinated plants expend less
energy in the production of pollinator attractants
and can grow in areas where the kinds of insects or
other animals that might visit them are absent or
very scarce—as in the Arctic or at high elevations.
Self-pollination limits the variety of progeny and may
depress plant vigor. However, self-pollination can be
advantageous, allowing plants to spread beyond the
range of suitable pollinators or produce offspring in
areas where pollinator populations have been
greatly reduced or are naturally variable.

18. Cross pollination

19. • Cross-pollination, also called allogamy, occurs
when pollen is delivered from the stamen of
one flower to the stigma of a flower on
another plant of the same species.[4]
Plants
adapted for cross-pollination have several
mechanisms to prevent self-pollination; the
reproductive organs may be arranged in such a
way that self-fertilisation is unlikely, or the
stamens and carpels may mature at different
times.[4]

20. Fertilisation
• Fertilisation
• Only after pollination, when pollen has landed on
the stigma of a suitable flower of the same
species, can a chain of events happen that ends
in the making of seeds. A pollen grain on the
stigma grows a tiny tube, all the way down
the style to the ovary. This pollen tube carries a
male gamete to meet a female gamete in an
ovule. In a process called fertilisation, the two
gametes join and their chromosomes combine,
so that the fertilised cell contains a normal
complement of chromosomes, with some from
each parent flower.

21. • The fertilised ovule goes on to form
a seed, which contains a food store and
an embryo that will later grow into a new
plant. The ovary develops into a fruit to
protect the seed. Some flowers, such as
avocados, only have one ovule in their
ovary, so their fruit only has one seed.
Many flowers, such as kiwifruit, have lots
of ovules in their ovary, so their fruit
contains many seeds.

22. Process of fertilization
• Occur in part :-The pistil

23. • Process 1

24. • Process 2

25. • Process 3

26. Made by:-