Download 23.2 Sexual Reproduction in Plants

Plant Reproduction and
Development
Chapter 23
23:1 Asexual Reproduction in
Plants
Asexual reproduction:
When an organism creates offspring that
are IDENTICAL to itself. Only one parent
is involved in asexual reproduction.
There is NO SWAPPING of genetic
material between TWO different parents.
Plants can reproduce asexually
There are 3 plant body
parts that a plant can
use for asexual
reproduction:
stems
leaves
roots
Asexual Reproduction by Roots
Many plants have
roots that can
grow into whole
new plants.
Each new plant has
its own root
system, stems
and leaves.
For instance:
If you place a sweet
potato into a glass of
water:
overtime the potato
will develop new leaf
shoots and roots
The new plant grows through
Mitosis
There is no egg or sperm
involved in this type of
reproduction.
There is no fertilization
involved.
There is no swapping of
genetic information
between two parents.
Many plants:
If cut down and the roots
are left intact in the
ground will grow new
stems and leaves.
A tuber: is an
underground root or
stem swollen with stored
food
Asexual reproduction by leaves
Some plants can reproduce
asexually from leaves.
Some leaves, when removed
from the main plant, will grow
into an entire new plant.
There is only one parent.
The new plant looks just like
the parent plants.
Asexual reproduction by stems
There are several ways that
stems of flowering plants
reproduce asexually.
A runner: is a stem that
grows along the ground or
in the air and forms a new
plant at its tip.
(the new tip can be potted
and becomes a whole new
plant)
Asexual reproduction by stems
Some stems are
underground:
potatos and onions are
both underground stems
Bulbs: are short
underground stems
surrounded by fleshy
leaves that contain
stored food
Everyday Applications:
Gardeners and farmers use their knowledge about
asexual plant reproduction in order to grow
plants from cuttings or graftings.
Cutting: a small section of plant stem that has
been removed from a parent plant and planted
to form a NEW PLANT
Grafting: is a process of joining a stem of one
plant to the stem of another plant.
23.2 Sexual Reproduction in
Plants
Flowers and Sexual Reproduction
Parts of a flower:
Sepal: often green, leaflike
parts of a flower that
protect the young flower
while it is a bud
Petals: are the brightly
colored parts and scented
parts of a flower. Used to
attract insects.
More Parts of a Flower
Stamen: is the male
reproductive organ
of the flower.
Usually 1 or more.
Pollen grains are
formed in the
stamen.
Flower Parts
Pistil: is the female
flower part.
Usually only 1.
Each pistil has a
large round
OVARY at its
base.
Flower Parts
Inside the ovary are
OVULES which
are the “eggs” for
the flower.
Pollination and Fertilization
Sexual reproduction:
swapping of genetic
information between two
parents.
In plants this occurs from
POLLINATION.
Pollination: is the transfer of
pollen from the male part of
a seed plant to the female
part
Pollination and Fertilization
In flowering plants the design of the flower is
important for pollination to occur.
Many flowers are brightly colored.
Many flowers are strongly perfumed.
Some flowers produce nectar.
Common Pollinators
Pollinators
Common Pollinators:
Insects, moths, butterflies, birds, and the
wind!
CROSS POLLINATION is when pollen from
the stamen of one flower is carried to the
pistil of another flower on a different plant
Cross Pollination
Self Pollination
Self
pollination:
Is when pollen
moves from
the stamen of
one flower to
the pistil of
the same
flower, or of
another
flower on the
same plant
How does pollination occur?
1. The pollen grain lands of the tip of the
pistil.
2. The pollen grows a tube INTO the stalk
of the ovary.
3. The tube reaches the ovule and the
sperm passes into the ovule to fertilize
the egg.
4. A new plant or embryo grows inside the
ovule and becomes a seed.
23.3 Plant Development
Seeds and Fruit
Flowers change after
fertilization occurs:
-after fertilization the ovules
have been fertilized by the
sperm in the pollen
-after fertilization the petals,
stamens and stalk of the
pistil wither and die
Seeds and Fruits
The ovules and the
ovary begin to grow
The ovules mature
into seeds
Seeds and Fruits
A seed: is a plant part that contains a plant
embryo
The embryo of a plant has a new young
plant and stored food.
This is a result of the joining of the egg and
sperm nuclei in the ovule
Seeds and Fruit
As the ovary matures
it becomes a fruit.
A fruit is an enlarged
ovary that contains
seeds.
Anything you eat that
has seeds is
considered a fruit!!!
These are ALL considered Fruit
Seeds and Fruit
One seed develops
from every fertilized
ovule in an ovary.
MEANING: in a
cherry there was
only one ovule. In
a peach there was
only one ovule. In
an apples there
were around 5
ovules. Etc….
Plant Development from Seeds
What happens to a fruit once they
have ripened?
-eaten by an animal and the fruit
part is digested and the seed is
passed in animal droppings after
the animal has traveled along
their daily activities.
OR
- More often the fruit stays on the
tree and eventually pops open to
drop the seed on the ground
Plant Development from Seeds
Larger seeds can
be taken away
by water.
Plant Development from Seeds
Some seeds
are taken
away by
the wind.
Plant Development from Seeds
The wind
disperses
these tiny
seeds from
the
dandelion.
Plant Development from Seeds
Burrs get stuck on
the fur of an animal
and will eventually
fall off during the
animals travels.
The seed is
surrounded by the
hooks that get
stuck on the
animal fur.
What happens next?
If a seed lands on soil that
has moisture and proper
temperature, it may
germinate.
Germination: the first
growth of a young plant
from a seed.
In many plants the main
part of the seed is the
source of food. It is
available for the growth
of the new plant.
What happens next?
In bean seeds the two
halves of the bean are a
food source for the
growing plant.
The stem that is coming out
of the bean seed have
leaves on them for
photosynthesis.
When the food supply from
the two halves of the
bean is used up they fall
off the plant.
Comparing Kinds of Reproduction
Asexual Reproduction
1.
2.
3.
4.
5.
One parent
Uses Mitosis
Produces adult plants in a short
time
Some plants don’t produce
seeds so can’t reproduce
sexually
All plants from asexual
reproduction are clones of the
original plant
Definition: A CLONE is a group of
living things that come from one
parent and are identical to the
parent
Comparing Kinds of Reproduction
Sexual Reproduction
1. Two parents
2. Characteristics from both parents
3. No two plants will have the same combination
of traits
4. A wide variety of traits in offspring
5. Seeds survive until the environment is right
for the survival of the seed and ultimately the
flower
6. The variety of traits allows the plants a better
chance to survive if conditions change.