PAGE - 8
C
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PAGE - 1
Sexual Reproduction in Flowering Plants
Key Concepts
Aids and Adaptations for Sexual Reproduction
Flowers have evolved several features to facilitate sexual reproduction:
Three Main Adaptations:
Flower size - Varies to suit different pollinators
Colorful petals - Attract insects for pollination
Scent - Chemical signals that guide pollinators
Reproductive Structures:
Male parts produce seeds (through pollen from stamens)
Female parts develop fruit (from the ovary)
These processes occur simultaneously in most flowering plants
how Flowers Are Formed
Flowers develop from the shoot apical meristem, which undergoes modification to form the
floral meristem.
The Transformation Process:
Floral Meristem Development is triggered by:
Hormonal changes (plant growth regulators)
Structural changes (cell differentiation)
The key hormones involved are Ethylene and Auxin, which signal the transformation from
vegetative growth to reproductive structures.
Development Pathway:
Shoot Apical Meristem → Floral Meristem → Bud → Flower
(Triggered by hormones (contains
& cytokinin) all flower parts)
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PAGE - 2
Structure of a Flower - Detailed Table
Whorl Components Parts Function Type Location
- Protect flower
- Individual
bud Accessory
sepal units
- Prevent whorl
Calyx Sepals - Usually green Outermost whorl
damage before (Non-
- Leaf-like
blooming reproductive)
structures
- Support petals
- Attract
- Individual pollinators
petal units (insects, birds) Accessory
- Brightly - Provide whorl Second whorl from
Corolla Petals
colored landing (Non- outside
- Various platform reproductive)
shapes & sizes - Contain nectar
glands
Anther:
- MALE
- Pollen sacs
reproductive
- Produces
part
pollen grains
- Produces male Essential whorl
Stamens Third whorl from
Androecium gametes (Reproductive -
(Microsporophyll) Filament: outside
(pollen) Male)
- Stalk/thread-
- Releases
like
pollen for
- Supports
pollination
anther
Gynoecium Carpels/Pistil Stigma: - FEMALE Essential whorl Innermost/central
(Megasporophyll) - Sticky top reproductive (Reproductive - whorl
surface part Female)
- Receptive to - Receives
pollen pollen on
stigma
Style: - Pollen tube
- Tube-like grows through
structure style
- Connects - Ovules
stigma to develop into
ovary seeds
C
,PAGE - 8
PAGE - 1
Sexual Reproduction in Flowering Plants
Key Concepts
Aids and Adaptations for Sexual Reproduction
Flowers have evolved several features to facilitate sexual reproduction:
Three Main Adaptations:
Flower size - Varies to suit different pollinators
Colorful petals - Attract insects for pollination
Scent - Chemical signals that guide pollinators
Reproductive Structures:
Male parts produce seeds (through pollen from stamens)
Female parts develop fruit (from the ovary)
These processes occur simultaneously in most flowering plants
how Flowers Are Formed
Flowers develop from the shoot apical meristem, which undergoes modification to form the
floral meristem.
The Transformation Process:
Floral Meristem Development is triggered by:
Hormonal changes (plant growth regulators)
Structural changes (cell differentiation)
The key hormones involved are Ethylene and Auxin, which signal the transformation from
vegetative growth to reproductive structures.
Development Pathway:
Shoot Apical Meristem → Floral Meristem → Bud → Flower
(Triggered by hormones (contains
& cytokinin) all flower parts)
, PAGE - 8
PAGE - 2
Structure of a Flower - Detailed Table
Whorl Components Parts Function Type Location
- Protect flower
- Individual
bud Accessory
sepal units
- Prevent whorl
Calyx Sepals - Usually green Outermost whorl
damage before (Non-
- Leaf-like
blooming reproductive)
structures
- Support petals
- Attract
- Individual pollinators
petal units (insects, birds) Accessory
- Brightly - Provide whorl Second whorl from
Corolla Petals
colored landing (Non- outside
- Various platform reproductive)
shapes & sizes - Contain nectar
glands
Anther:
- MALE
- Pollen sacs
reproductive
- Produces
part
pollen grains
- Produces male Essential whorl
Stamens Third whorl from
Androecium gametes (Reproductive -
(Microsporophyll) Filament: outside
(pollen) Male)
- Stalk/thread-
- Releases
like
pollen for
- Supports
pollination
anther
Gynoecium Carpels/Pistil Stigma: - FEMALE Essential whorl Innermost/central
(Megasporophyll) - Sticky top reproductive (Reproductive - whorl
surface part Female)
- Receptive to - Receives
pollen pollen on
stigma
Style: - Pollen tube
- Tube-like grows through
structure style
- Connects - Ovules
stigma to develop into
ovary seeds
