SEXUAL REPRODUCTION IN PLANTS
Sexual reproduction involves the fusion of special reproductive cells (specialised
cells) called gametes
In flowering plants, sexual reproduction takes place in the flowers which are organs
of sexual reproduction
There are special mechanisms, that is pollination and fertilisation which ensure that
the male and female gametes meet and fuse
Flowers can be unisexual that is contain either the female part or the male part.
Flowers can also be bisexual that is they contain both the male and female part
,Structure of a flower
1.Sepal
They are modified leaves which enclose and protect the other parts of the flower in
bud stage
All the sepals together make up the calyx
They are usually green
2. Petals
They are modified leaves forming the conspicuous part of the flower
The petals together make up the corolla
They are usually brightly coloured to attract insects for pollination
They provide a landing platform for insects (so they are large)
Usually, at the base of the petal, there is a small sac-like structure called the nectary
which contains nectar. This is a sugary solution to attract insects. Some petals may
have darker lines called the insect guides to direct the insects to the nectaries.
, 3. Stamen
The male part of the flower
Each stamen is made of a filament which supports the anther
Each anther consists of four pollen sacs in which pollen grains are produced by cell
division that is meiosis
When the anthers are ripe, the pollen sacs split open and release their pollen
The anther also contains a vascular bundle
(a)The phloem translocates sucrose and amino acids. Sucrose provide energy for cell
division and amino acids are used for synthesis of proteins and new protoplasm
(b)The xylem transports water and mineral salts to the anther
Sexual reproduction involves the fusion of special reproductive cells (specialised
cells) called gametes
In flowering plants, sexual reproduction takes place in the flowers which are organs
of sexual reproduction
There are special mechanisms, that is pollination and fertilisation which ensure that
the male and female gametes meet and fuse
Flowers can be unisexual that is contain either the female part or the male part.
Flowers can also be bisexual that is they contain both the male and female part
,Structure of a flower
1.Sepal
They are modified leaves which enclose and protect the other parts of the flower in
bud stage
All the sepals together make up the calyx
They are usually green
2. Petals
They are modified leaves forming the conspicuous part of the flower
The petals together make up the corolla
They are usually brightly coloured to attract insects for pollination
They provide a landing platform for insects (so they are large)
Usually, at the base of the petal, there is a small sac-like structure called the nectary
which contains nectar. This is a sugary solution to attract insects. Some petals may
have darker lines called the insect guides to direct the insects to the nectaries.
, 3. Stamen
The male part of the flower
Each stamen is made of a filament which supports the anther
Each anther consists of four pollen sacs in which pollen grains are produced by cell
division that is meiosis
When the anthers are ripe, the pollen sacs split open and release their pollen
The anther also contains a vascular bundle
(a)The phloem translocates sucrose and amino acids. Sucrose provide energy for cell
division and amino acids are used for synthesis of proteins and new protoplasm
(b)The xylem transports water and mineral salts to the anther
