Transcript Principals of Flowering Plants Taxonomy9x

Dr. Najat Abdulwahab Bukhari
Lecture 9
University Vision and Mission

Vision:
To be a world-class university and a leader in
developing Saudi Arabia’s knowledge economy

Mission:
To provide students with a quality education,
conduct valuable research, serve the
national and international societies and
contribute to Saudi Arabia’s knowledge
economy through learning, creativity, the use
of current and developing technologies and
effective international partnership.
Botany department Vision and
Mission
Vision:
upgrading the academic and research to keep pace
with scientific progress and requirements of society.
Mission:
Development of Academic process and develop
scientific research through strategic planning and a
clear vision for science and technology at the country
level. As well as training of national cadres, and the
introduction of a methodology developed to meet the
different needs of society, and to serve the various
research and developmental projects in the community
Course Description
Topics to be Covered
Topic
- Historical review of plant taxonomy (industrial ,
natural, evolution)
- Nomenclature
- Classic taxonomy (morphological taxonomy of
vegetation and floral characters – Fruits and seed
characters.
- Key to taxonomical unites.
- Fertilization and seed formation
- The different kinds of fruits
- The sexual differentiations of flowers and their
fertilization
No of
Weeks
Contact
hours
1
2
1
5
2
2
1
2
2
2
2
2
2
2
14
14
Androecium
Male reproductive organ of a flower.
The stamens are collectively referred
to as the androecium. The number and
position of the stamens are significant
in the classification of flowering plants
A typical stamen consists of :
1- filament, The stalk of a stamen in a flower,
supporting the anther, differ in shape depending on
pollination method.
2- anther, The pollen-bearing part of the stamen of
a flower, consists of two lobs each one contains the
pollen sacs.
3- Connective: connects the two lobs.
Pollination
Is the process of transition of pollen grains
from the anther of flower to the stigma of
another flower on the same plant or another
flower of the same type or another plant.
Pollination types
 Auto Pollination
Transition of pollen grains
from the anther to the
stigma of flower on the
same plant.
 Cross Pollination
Transition of pollen grains from
the anther to the stigma to
another flower of the same
plant or a different plant.
Auto Pollination
First: wind pollination
Advantages:
 Very small pollen grains.
 Dense population of plant.
 Light in weight.
 Have wing or hairs that
aids in wind dispersal.
 Feathery stigmas. (such as
Graminaceae family).

Second : animal pollination
(zoidiophilae)
1- insect pollination (Entomophily )
 Such
as butterflies,
bees, flies and ants.
The insects feed on
the nectar or pollen or
both of them .
Characteristics of insect pollination plants:
1. Bright color petals, with
strong adore , some with
foul odors to attract
special kind of insects.
2. The flowers produce
nectars, so that the
insects and its larva fed
on this nectar (diluted
sugary syrup ).
4. Some flowers has (honey
guides) Colorful spots or
stripes on a flower that
indicate to insects where the
nectar is produced.
4. Large numbers of pollen
grains enough to fed insects
and for the pollination
process.
5. Pollen grains has spins, and
sticky so it can stick on the
insects. The stigma also is
sticky and not branched.
2- Birds pollination (Ornithophilae)
 This distinguishes tropical
and under tropical forests
plants. Pollination with birds
is similar to insect pollination
but the flowers has some
characteristics
such
as
tubular corolla is pollinated
by a bird with a A shape
beak.
Some birds break through
the corolla and suck the
nectar.
Very bright colors flowers to
attract birds for pollination.
When birds sucks nectar
with its long beak, pollen
grains scattered on its head.
Pollination happens when the
birds head touches another
flower’s stigma.
3- Mollusks pollination
By mollusks such as snails in plants that
grow in the swamps.
artificial pollination
How it is done:
1- Cut and remove the stamens of bisexual
flowers before maturity in order not to be
self-pollination, then cover and keep the
flowers-containing the carbala with solvent
bags in order not get wind or insect
pollination.
Single-sex flowers,
covered only.
female
flowers
is
2- Pollen grains of mature stamens is
collected in clean containers. Then the
pollen grains brushed with small brush on
the stamens of the female flowers. The
fertilized flowers then covered and kept in
solvent bags. It remain in the bags until the
seeds began to grow .
3- The hybrid seeds then is grown to see the
new characters.
Pollen Tube
The pollen tube arises from
the tube nucleus inside the
pollen grain and grows
through the tissue of the
style and ovary. Eventually,
the pollen tube reaches the
ovule, permitting the sperm
nuclei to reach the ovule
and fertilize the egg cells
During the passage the fed from the
tissue of the stamen and the wall of the
ovary.
When the tube inters through the micropyle
it reaches the apex of the nucleus , the apex
dissolved and the two male gametes passes
through the embryo sac.
Porogamic : Passage of the pollen tube to the
nucleus through the micropyle of an ovule in a seed.
Chalazogamic : Passage of the pollen tube to the
nucleus through the chalaza of an ovule in a seed.
Some times the pollen tube enters into an ovule
through integuments or funicle. It is called as
mesogamy
Fertilization and seed formation
After fertilization zygote stays for a period of
time then the endosperm cell starts to dived
rapidly to form the endosperm tissue.
 First cell division gives 4-8 cells.
 Then the base cell near the micropyle start

elongation pushing other cells into the
endosperm.
 At the same time the far cell from the
micropyle dived into tow cells before turning
into ambryo.
 Then
divided several divisions to give the
spherical shape of the ambryo, with
several other divisions gives the heart
shape, which tunes into the two seed lobs.

During the ambryo formation, the nucleus
, endosperm and cover tissue change a lot
according to the type of seed. The nucleus
and endosperm exist at the first stages of
the embryo formation , they are used as
fed in these stages only.
 The

embryo grow from the zygote.
Testa (seed coat) develops from the inner
and outer tissue that surround the egg.
 Sperm
cell (n) + egg cell (n)
 Sperm
zygote (2n)
cell (n) +polar nucleus (2n)
endosperm nucleus (3n)
 Endosperm
nucleus divided
Fertilization
Fertilization is the fusion of the sperm with
the egg.
 There are 3 stages before fertilization:
 The formation of the sperm and egg.
 Transfer of pollen grains from anther of a
stamen to the stigma of carbala.
 The formation of the pollen tube which grow
through the style and ovary to reach the
nuclei. The apex of the tube dissolve and
empty its contains

Double fertilization happen one sperm moves
to the egg to form zygote. The other sperm
fuses with the polar nuclei in the primary
endosperm cell (2 sets of chromosomes)
diploid. (2n)
 Another sperm fuses with the secondary
embryo sac nucleus to form endosperm cell
(3 sets of chromosomes ) triploid. (3n)
 Other cells acts as food for the embryo sac.
 Zygote develops into the

Endospermic seeds are seeds whereby the
endosperm is present in the mature seed
and serves as food storage organ. Testa
and endosperm are the covering layers of
the embryo. (as in corn)
Non-endospermic
seeds
are
seeds whereby the cotyledons
serve as sole food storage
organs.
During
embryo
development
the
cotyledons
absorb the food reserves from the
endosperm. The endosperm is
almost degraded in the mature
seed and the embryo is enclosed
by the testa. (as in beans)
perisperm The nutritive tissue that is derived from
the nucleus and surrounds the embryo of the seed.
Testa is the outer protective layer of the
seed, and egg, it surrounds all around apart
from the micropyle bare.
Hilum is The scar on a seed, such as a
bean, indicating the point of attachment to
the funiculus.
Funiculus is a stalk connecting an ovule or a
seed with the placenta. It passes food from
the placenta to the egg until the seed mature.
Egg……….seed
Ovary………fruit.