POLLINATION
parts of a flower
A flower generally contains four parts: calyx, corolla, androecium, and gynoecium.
These are also called the four whorls of a flower. The stalk of a flower is called the
pedicel. The swollen end of the pedicel is called the thalamus.
calyx:The outermost whorl of a flower is called the calyx. It contains a set of green leaf-
like structures called sepals. There may be five or more sepals in a flower.
Function The main function of sepals is to protect the flower in the bud stage.
They can also prepare food for the plant.
corolla:The second whorl of a flower is called the corolla. It generally consists of a ring of
brightly coloured leaf-like structures called petals.
Function Since petals are generally brightly coloured, they attract insects that
help in pollination. They may also produce different scents to attract insects
towards the flower.
click to edit
Androecium
The third whorl of a flower is the androecium. It is the collection of stamens. Each
stamen has a long slender stalk called filament. An anther is present at the tip of
the stamen. Anthers produce dust-like particles called
pollen grains. Pollen grains contain the male gametes
or male reproductive cells.
click to edit
Function The stamen is the male reproductive unit of
a flower. Stamens of the flower are collectively called
androecium.
click to edit
Gynoecium
The gynoecium is usually located at the centre of a flower. It is a collection of the
female reproductive units called carpels or pistils. A gynoecium may consist of a
single pistil or a group of pistils. A pistil has three parts—stigma, style, and ovary.
Stigma is the sticky, swollen tip of the pistil. It is responsible
for receiving the pollen grains.
Style is a thin, long, tube-like structure that connects the
stigma to the ovary.
Ovary is the swollen base of the pistil. It contains ovules.
The ovules contain eggs or the female gametes.
Function After fertilization, the ovary forms the fruit of the
plant, whereas the ovules form the seeds.
what's pollination
and insects.
plant to another, with the help of wind, water, birds,
grains are transferred within a plant, or from one
stigma by various agents is called pollination. Pollen
The transfer of pollen grains from the anther to the
the process of pollination:
Pollination is the first step in the process of seed formation. The male reproductive
cells (or gametes) are present in the pollen grains that are inside the anther. The
female reproductive cells (or gametes) are present in the ovules contained in
the ovary. Both the male and female gametes must come in contact with each
other for reproduction to take place. When the anthers mature, they split open
and the pollen grains are set free. The pollen grains may fall on the stigma of the
same flower (in case of bisexual flowers). They may also be carried to the stigma of
another flower belonging to the same kind by the different agents of pollination.
types of pollination:
Pollination is of the following two types.
Self-pollination
When the pollen grains from the anther of one flower fall on the stigma of the
same flower, or of another flower present on the same plant, the process is called
self-pollination. Self-pollination is commonly seen in pea plants.
Cross-pollination
When the pollen grains from the anther of one flower are transferred to the stigma
of another flower, present on a different plant of the same kind, the process is
called cross-pollination. Cross-pollination occurs in most flowering plants.
click to edit
click to edit
click to edit