2. POLLINATION
Pollination is the transfer of pollen grains from an anther to the stigma.
– an anther is part of the stamen which is the male part of the flower.
– Stigma is part of the pistilate which is the female part of the flower
4. TYPES OF POLLINATION
1. Self-pollination:
–transfer of pollen from an anther to the stigma within the same flower or
to a different flower of the same plant.
(a) Autogamy
(b) Geitonogamy
5. Continuation of the type of pollination
2. Cross-pollination:
– transfer of pollen grains from an anther to the stigma of a
different plant of the same species.
These processes are done by the following agents:
–insects, wind, birds, bats, water and other animals.
7. CHARACTERISTICS OF FLOWERING
PLANTS POLLINATED BY ANIMALS
Color – Bright colors, mostly yellow and blue
Shape – give room to the pollinators to easily access the pollen
Fragrance – they have nice and strong scents
8. FERTILIZATION
Fertilization is the union of the sperm cell and the egg to form a zygote which
develops into an embryo and finally a seed
Process
Pollen grain at the stigma absorbs a fluid from the stigma,
It bulges and produces a tube(pollen tube) through the aperture
The tube grows down through the style to the ovule in the ovary
Vegetative nucleus stays at the tip as the generative nucleus lags behind and
undergoes through mitosis to produce two sperm cells
9. DIAGRAMS SHOWING THE POLLEN
GRAIN AND A MATURE MALE
GAMETOPHYTE.
Sperm
cells
Vegetative nucleus
Pollen tube
pollen grain
aperture
Pollen grain Matured gametophyte
11. Double fertilization
One of the sperms unites with an egg to form a zygote.
The other sperm unites with the central nuclei to form a 3n (triploid ) endosperm.
The 3n endosperm surrounds the embryo that develops from the zygote to provide
the nutrients.
Eventually the ovary develops into a fruit and the ovule into a seed.
