Slide 1
Sexual
Reproduction
in
Plants
Slide # 2
Flower Structure
Stigma Ovary  Fruit
Style
Ovule  Seed
Anther
Filament
Ovule
Petal
Sepal
Pistil (female Part)
 Stigma
 Style
 Ovary
Receptacle
Stamen (Male Part)
Anther
Filament
Ovary
Slide # 3
Structure of a Flower
1.Pistil:female reproductive
structure
a.Stigma: sticky tip; traps
pollen
b.Style: slender tube;
transports pollen from
stigma to ovary
c.Ovary: contains ovules;
ovary develops into fruit
d.Ovule: contains egg
cell which develops into
a seed when fertilized
Stamen
Anther
Filament
Ovule
Stigma
Pistil
Style
Ovary
Petal
Sepal
Slide # 4
Structure of a Flower
2.Stamen: male
reproductive structure
a.Filament: thin stalk;
supports anther
b.Anther: knob-like
structure; produces
pollen
c.Pollen: contains
microscopic cells that
become sperm cells
Stamen
Anther
Filament
Ovule
Stigma
Pistil
Style
Ovary
Petal
Sepal
Slide # 5
Slide # 6
Perfect & Imperfect Flowers
Perfect Flower ~ has pistil & stamen
Imperfect Flower ~ only one sex
Slide # 7
Structure of a Flower
3.Sepals: encloses &
protects flower before it
blooms
Stamen
Anther
Filament
Stigma
Pistil
Style
Ovary
4.Petals: usually colorful
& scented; attracts
pollinators
Ovule
Petal
Sepal
Slide # 8
Slide # 9
Pollination
The transfer of pollen grains from the anther to the
stigma.
Pollination may be aided by wind, insects, and birds.
In some instances, the colored petals act as a visual
attractant for insects.
If pollination occurred in a dry environment, the
pollen would not dehydrate (dry up) due to a thick
wall that surrounds it.
Two types of pollination:
1. Self-Pollination
2. Cross-Pollination
Slide # 10
Self-Pollination
The transfer of pollen grains from the anther to the
stigma of the same plant.
Cross-Pollination
The transfer of pollen grains from the anther of a flower
on one plant to the stigma of a flower on a different
plant.
Allows for variations due to the combination of two
different plants.
Slide # 11
Following pollination, the
pollen grain germinates
to the stigma and forms
a pollen tube.
Pollen tube is an
adaptation for internal
fertilization.
2 Haploid sperm cells
travel down the pollen
tube and only one
fertilizes the egg in the
ovule.
Slide # 12
Fertilization and Embryo Development
The union of a sperm cell and an egg cell results
in the formation of a zygote
The zygote undergoes development resulting in
the formation of an embryo (ripened ovule)
The ripened ovule (embryo) develops into the
seed
The ripened ovary develops into the fruit
Slide # 13
Structure of a Seed (embryo)
Hypocotyl: Develops into
roots and in some
species lower stem.
Radical: Develops in roots
Epicotyl: Develops into
leaves and upper stem
Cotyledon: Stored food for
early development of embryo
(seed leaves)
Slide # 14
Structure of a Seed
Epicotyl
Slide # 15
Seed coat:
• forms from outer layer of ovule
• protects embryo
Endosperm: food storage tissue
(the other sperm creates this triploid (3n) structure
when it fertilizes 2 polar bodies from oogenesis)
Slide # 16
Monocots & Dicots
Monocots – seeds with one cotyledon (corn)
Dicots – seeds with two cotyledons (bean, peanut)
Slide # 17
Germination and Growth
Fruits are specialized structures
which aid in seed dispersal.
Seeds develop inside the fruit.
If the temperature and moisture
levels are sufficient, the
dispersed seeds will germinate
(activate and grow).
Growth in most plants occurs in the meristems.
The organs of a plant are developed in the meristems.
Apical Meristems are found in the tips of roots and stems
and cause the plant to grow in height.
Lateral Meristems are between the xylem and phloem and
cause the plant to grow in diameter (get wider).
Slide # 18
Plant
Responses
and
Adaptations
Slide #19
Hormone Action on Plants
A. Plant cells can produce
hormones (chemical
messengers that travel
throughout the plant
causing other cells called
target cells to respond)
B. In plants, hormones
control:
Movement
of hormone
Hormoneproducing
cells
Target
cells
1. Plant growth &
development
2. Plant responses to
environment
Cells in one blooming
flower signals other blooms
using hormones to open.
Slide # 20
Plant Hormones
Auxin
High Auxin ~ stimulates stem growth
~ inhibits root growth
Low Auxin ~ reverse effect
Gibberellin
• Increases stem growth
• Increases fruit and seed development
Slide # 21
Plant cells will send signals
to one another to tell them:
1. When trees to drop their leaves.
2. When to start new growth.
3. When to cause fruit to ripen.
4. When to cause flowers to bloom.
5. When to cause seeds to sprout.
Tree
Budding
Fruit
Ripening
Cactus
Blooming
Leaf Drop
Sprouting
Corn Seeds
Slide # 22
Ethylene causes
Fruit to Ripen
1.Fruit tissues release a
small amount of ethlyene
2. Ethylene is a gaseous
hormone
3.Causes fruits to ripen
4.As fruit become ripe, they
produce more and more
ethlyene, accelerating
the ripening process
Ethylene released
by apples and
tomatoes causes
fruit to age quickly.
Slide # 23
Plant Tropisms
Tropism: the way a plant grows in response to
stimuli in the environment caused by an unequal
distribution of auxin.
Phototropism: growth response to light
-Plants bend towards light
Geotrophism: growth response to gravity
-plant roots grow down with gravity, shoots (stems) grow
up against gravity and out of the soil.
Thigmotropism: growth response to touch
-vines grow up around trees, venus flytrap closes when
leaves are touched
Slide # 24
What type of tropism is shown in these pictures?