Transcript Flower Structure - onlinebiosurgery

Flower Structure
Objectives:
*State the functions of different parts of a flower
**Describe the structures of insect and wind pollinated flowers
*** Compare the adaptations of flowers and pollens of insect and
wind pollinated flowers
Nectary
Sepal
Protects
the flower
in bud
Petal
Stamen
Male organ. Anther is
Bright colour and scent for where the pollens
attracting pollinating
Pollen is the male sex
agents Many have nectary cell (gamete).
at base to make nectar for are made and the
filament holds up the
feeding insects.
anther so the flowers
can be pollinated
easily
Carpel
Female organ. Ovary
contains the ovule s
which has female
gametes. Stigma is
where the pollen
lands, style connects
the ovary to the
stigma
Insect pollinated
Wind pollinated
Petals
Large brightly coloured
and scented to attract
insects
Small, green
inconspicuous flowers , no
scent
Nectaries
Produces sugary nectar to
attract insects
No nectary
Stamen
Anthers inside so insects
can rub against them
Anthers hang outside so
wind can blow away
large quantities of pollen
Pollen
Sticky, spikey,
Carpels
Sticky short stigma
positioned inside the
flower for insects to rub
against it.
Made in large quantity as a
lot can get wasted, smooth
and light
Feathery long stigma
positioned outside the
flower which act as nets to
catch as much pollen as
possible
Pollination
Objectives:
*Define self and cross pollination
**Name agents of pollination
*** Discuss significance of self and cross
pollination
Sexual reproduction in flowers
1. Pollination occurs when pollen grains
from the stamen land on the stigma of the
carpel
2. Fertilisation occurs when the male sex
cell in the pollen fuses with the female sex
cell in the ovule
Sexual reproduction in flowers
Self Pollination
Cross Pollination
Advantages
1. No pollinating insects
1. Variation due to
needed
exchange of genetic
2. Plants growing in
material
isolation from others of 2. Dispersed away from
the same species can
each other leading to
still get pollinated
no intraspecific
3. Well adapted to the
competition
same environment as
3. Well adapted to change
their parents
in environment due to
4. Pollination is more
variation upon which
successful
natural selection can
operate
4. Well suited for
evolution
Disadvantages
1. Very little variation
unless there is a
mutation which may
not be expressed
2. Very limited chance of
evolution
3. Intraspecific
competition
1. Dependant on
pollinating insects
2. Plants in isolation will
not be able to
reproduce
3. Pollination is a
question of chance