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SEXUAL REPRODUCTION IN FLOWERING PLANTS:
Introduction:
We know that in angiosperms, parent plant is
diploid sporophyte generation
...
The
flower components are arranged in the form of
whorls
...

Calyx: is the outer most whorl
...
Its individual units (leaflets) are called
sepals
...

Corolla is the next inner whorl and is often coloured
brightly
...
They serve to attract bees, birds, etc
...

|the flower is actually a condensed shoot with the
nodes present very close to each other
...
All the structures present at one node are
collectively called the whorl|
...
e androecium is the male reproductive
part of flower
...
Each
stamen has a thread-like filament at the free end of
which anther is attached
...
Each microspore
germinates into the male gametophyte generation
...
e a tube nucleus
And a generative nucleus
...
All
these structures are the male gametophyte
generation of plant
...
e gynoecium is the female
reproductive part of flower
...
Each carpel is made up of the
basal ovary, middle style and upper stigma
...
Inside each

value, one haploid macrospore is produced through
meiosis
...
During it, macrospore
undergoes mitosis and produces an egg cell and
some associated structures (e
...
Egg
cell and associated structures are the female
gametophyte generation of plant
...
These
may either be fused or free|
...
He laid a solid foundation of
botany including the morphology and functions of
the flowers
...

When pollen grains mature, they are transferred to
stigma
...
On reaching the
stigma, the tube nucleus of pollen grain constructs a
Pollen tube
...
The tube grows through
style and ovary and enters ovule
...
Both sperms enter the female
gametophyte
...
The other sperm fuses with diploid
fusion nucleus and forms a triploid (3N) nucleus
called Endosperm nucleus
...


Zygote develops into embryo and endosperm
nucleus develops into endosperm tissue (food of
the growing embryo)
...
When seeds mature,
they are dispersed, if seeds get suitable conditions,
their embryos develop into new plants ( the diploid
sporophytes of the next generation)
...

Types: two types of pollination are recognized
...

➢ Cross Pollination: is the transfer of pollen
grains from the flower on one plant to the
flower on other plant of the same species
...


The insect pollinated and wind pollinated
flowers have structural adaptations that
facilitate the transfer of pollen grains
between two plants
...

Table: Adaptations in insect-Pollinated and

wind Pollinated Flowers
Features
Insects
Pollinated
flowers
Size
Generally
large
Colur
Petals brightly
coloured
Nectar

Produce
nectars

Floral
arrangement

Flowers face
upwards

Stamens and
stigmas

Enclosed
inside ring of
petals
Small number
produced/
heavy and
sticky

Pollen grains

Wind
Pollinated
flowers
Generally
small
Petals green
or dull in
colour
Do not
produce
nectar
Flowers hang
down for easy
shaking
Hang out of
ring of petals
Large number
produced/
light with
smooth
surface

Stigma

Pinhead
shaped with
no branches

Feathery
branches for
catching
pollen

Initiating and planning:
➢ Hypothesize why Mendel used Pea plants for
his experiments
...

This process is known as Parthenocarpy and it
results in seedless fruits e
...

➢Examples of insect’s pollinated:

Examples of insect’s pollinated flowers are
buttercup, rose, wallflower, sunflower, orchid
etc
...




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