Concept Capsule 1: Class XII

Sexual Reproduction in Flowering Plants


1. Flower – Reproductive Organ

Floral WhorlComponentsFunctionNCERT Example
CalyxSepalsProtects budMustard
CorollaPetalsAttract pollinatorsHibiscus
AndroeciumStamensMale reproductionLily
GynoeciumPistilFemale reproductionPea

2. Male Reproductive Structure (Anther)

Important Facts

FeatureDescription
Typical AntherBilobed
Microsporangia4
Pollen-producing structureMicrosporangium

Wall Layers

LayerFunction
EpidermisProtection
EndotheciumDehiscence
Middle LayersTemporary nourishment
TapetumNourishes pollen grains

NCERT Examples

ConceptExample
Tapetal abnormalities causeMale sterility
Sporopollenin-rich pollenAll flowering plants

3. Microsporogenesis

Sequence

PMC (2n) → Meiosis → 4 Microspores (n)

NCERT Example

ConceptExample
Microspore tetradLily

4. Pollen Grain

Structure

PartComposition
ExineSporopollenin
IntineCellulose + Pectin

Cells

CellFunction
Vegetative CellPollen tube formation
Generative CellMale gametes formation

NCERT Examples

ConceptExample
Pollen viability for monthsRosaceae, Fabaceae, Solanaceae
Pollen viability for 30 minRice, Wheat
Pollen tabletsNutritional supplements

5. Female Reproductive Structure (Ovule)

Parts

PartFunction
FunicleAttachment
HilumJunction
MicropyleEntry of pollen tube
NucellusNutrition
ChalazaBasal region

NCERT Example

ConceptExample
Anatropous ovuleMost angiosperms

6. Megasporogenesis

MMC → Meiosis → 4 Megaspores

NCERT Facts

FeatureFact
Functional MegasporeOne
Degenerating MegasporesThree

7. Embryo Sac

Mature Embryo Sac

CharacteristicValue
Cells7
Nuclei8
DevelopmentMonosporic

Arrangement

RegionComponents
Micropylar EndEgg + 2 Synergids
Central Cell2 Polar Nuclei
Chalazal End3 Antipodals

NCERT Examples

ConceptExample
Typical embryo sacPolygonum type
Filiform apparatusSynergids

8. Pollination

Types

TypeDefinitionExample
AutogamySame flowerPea, Wheat
GeitonogamyDifferent flowers of same plantMaize
XenogamyDifferent plantsPapaya

9. Pollinating Agents

Wind Pollination (Anemophily)

Features

  • Light pollen
  • Dry pollen
  • Feathery stigma

NCERT Examples

PlantCharacteristic
MaizeWind pollination
CoconutWind pollination
GrassesWind pollination

Water Pollination (Hydrophily)

NCERT Examples

PlantCharacteristic
VallisneriaSurface pollination
ZosteraSubmerged pollination

Insect Pollination (Entomophily)

NCERT Examples

PlantCharacteristic
SalviaInsect pollinated
SunflowerInsect pollinated
OrchidInsect pollinated

Orchid Special Example

OrchidPollinator
OphrysBee

Bird Pollination

Example
Erythrina

Bat Pollination

Example
Kigelia

10. Outbreeding Devices

DeviceFunction
DichogamyDifferent maturation times
HerkogamyPhysical separation
Self-IncompatibilityGenetic barrier
DioecySeparate sexes

NCERT Examples

DeviceExample
DioecyPapaya
Self-incompatibilityBrassica

11. Artificial Hybridization

Emasculation

Removal of anthers before dehiscence.

Example

Plant TypeMethod
Bisexual FlowerEmasculation needed
Unisexual Female FlowerEmasculation not required

Bagging

Covering flower to prevent contamination.


12. Double Fertilization

Syngamy

Male gamete + Egg → Zygote

Triple Fusion

Male gamete + 2 Polar Nuclei → PEN

Double Fertilization

Occurs only in flowering plants.

NCERT Example

ConceptExample
Double fertilizationAll Angiosperms

13. Endosperm

Function

Provides nutrition to embryo.

Types

TypeExample
NuclearCoconut
CellularDatura
HelobialMonocots

NCERT Example

StructureExample
Free nuclear endospermCoconut Water
Cellular endospermCoconut Kernel

14. Embryo

Dicot Embryo

Example

Plant
Pea
Gram

Monocot Embryo

Example

Plant
Maize
Wheat

Important Structures

StructureFunction
ScutellumCotyledon
ColeoptileProtects plumule
ColeorhizaProtects radicle

15. Seed

Dicot Seed

Example
Pea
Gram
Bean

Monocot Seed

Example
Maize
Wheat
Rice

16. Apomixis

Seed formation without fertilization.

NCERT Examples

ExampleType
CitrusApomixis
MangoApomixis
AsteraceaeApomixis
GrassesApomixis

17. Polyembryony

More than one embryo in a seed.

NCERT Examples

Example
Citrus
Orange
Mango

NCERT Examples Master Table

ConceptExample
AutogamyPea, Wheat
GeitonogamyMaize
XenogamyPapaya
Wind PollinationMaize, Coconut
Water PollinationVallisneria, Zostera
Insect PollinationSalvia, Sunflower
Bird PollinationErythrina
Bat PollinationKigelia
Dioecious PlantPapaya
Self-IncompatibilityBrassica
Typical Embryo SacPolygonum
Orchid PollinationOphrys–Bee
Free Nuclear EndospermCoconut Water
Monocot SeedMaize
Dicot SeedPea
ApomixisCitrus, Mango
PolyembryonyCitrus
Long-Lived PollenRosaceae, Fabaceae, Solanaceae
Short-Lived PollenRice, Wheat