Flowering plants reproduce sexually through a process involving flowers, pollen, and double fertilization. Flowers contain reproductive organs including stamens which produce pollen inside anthers. Pollen grains contain male gametes that develop inside pistils after pollination. Double fertilization involves one male gamete fusing with the egg cell to form the embryo, and the other with polar nuclei to form endosperm tissue. The fertilized ovule develops into a seed containing the embryo and food reserves. Fruits form from the ripened ovary and contain seeds, completing the plant life cycle.
2. FLOWER- REPRODUCTIVE ORGAN OF PLANTS
PARTS OF A FLOWER
• CALYX (whorl of sepals)
• COROLLA (whorl of
petals)
• ANDROECIUM (group of
stamens)
• GYNOECIUM (group of
carpels)
3. PRE-FERTILISATION: STRUCTURE
AND EVENTS
STRUCTURE OF STAMEN
• Consist of two parts:
1. Long stalk- Filament
2. Bilobed terminus- Anther
• Eachanther has two lobes; eachlobe has two
eachlobe has twotheca.
• Eachtheca is called Microsporangia (Pollen
Microsporangia (Pollensacs)
sacs)
4. STRUCTURE OF MICROSPORANGIA
• It has four layers:
• Epidermis
• Endothecium
• Middle layers
These three helps in protection
• Tapetum
• It provides nutrition to Developing pollen grain
5. MICROSPOROGENESIS• Sporogenous tissue develop to form dipoild
Pollen mother cells.
• Pollen mother cell undergoes meiosis to form
four microspores.
• Microsprores attach as tetrad
• Later tetrad loses moisture , become dry and
separates.
• Anther dehiscence.
6. STRUCTURE OF POLLEN GRAIN (MICROSPORE)
• Two layers-
• Exine- Outer LayeR ; Made up of
sporopollenin (Most resistant organic
material)
• At some exine is absent- Germ pores
• Intine- Inner layer; made up of cellulose
and pectin
7. DEVELOPMENT OF POLLEN GRAINS
• Microspore Divide by Mitosis to form two cells:
1. One large vegetative
2. Smaller generative
• Generative again divide By mitosis- to form two male
gametes.
8. STRUCTURE OF PISTIL
Has three parts:
• Stigma
• Style
• Ovary- Contain ovules
• Types
• Syncarpous- Fused carpels
• ApocarpoUs- not attached
9. STRUCTURE OF OVULE
• Funicle- stalk attaching to placenta
• Hilum- region where ovule fuses with
funicle
• Outer integument- Protective envelope
• Inner integument- Protective envelope
Micropyle
• Nucellus- parenchymatous tissue; give
nutrition to embryo sac
• Embryo sac- female gametophyte
• viii) Micropyle- where integument absent;
aperture for pollen tube entry.
12. POLLINATION
• Three typesof pollination
• Autogamy
• Geitonogamy
• Xenogamy
• Some plantshave two kindsof flowers
• Chasmogamous (open)
• Cleistogamous(close)
13. AGENTS OF POLLINATION
• Abiotic
1. Water
2. Wind
• Water pollinated flowers called hydrophilous
• Wind pollinated flowers called anemophilous
• Biotic factors
• Insects (bees, wasp, flies, beetles, butterflies)
• Birds( sunbird and hummingbird)
• Larger animals like lemurs, reptiles
• Bats
• Insect pollinated flowers called Entomophilous.
14. WIND-POLLINATED FLOWERS (ANEMOPHILOUS)
• Inconspicious flowers
• Pollen grains produced in large numbers
• Well-exposed stamens
• Dry,light and non-sticky pollen grains
• Feathery and sticky stigma
• Single ovule
15. WATER POLLINATED FLOWERS
(HYDROPHILOUS)
• Flowers lack scent and nectar; not showy.
• Pollen grains produce in large numbers.
• Pollen grains are light and have
mucilagenous covering (make it
unwettable)
• Sticky and unwettable stigma.
16. INSECT POLLINATED FLOWERS
(ENTOMOPHILOUS)
• Large and showy;
• Colourful; have scent and nectar
• Flowers pollinated by flies and beetles produce
foul smell.
• Pollen grains and stigma are sticky
• Flowers have landing platform; floral rewards
17. OUTBREEDING DEVICES
• Methods to prevent self pollination
• To promote cross pollination
• Because continued self pollination
cause inbreeding depression
• Unisexuality
• Dichomgamy – Protandry and
protogyny
• Self incompatibility
• herkogamy
18. ARTIFICIAL HYBRIDISATION
• Emasculation:- Cutting of anther
• Bagging- Covering stigma with a bag made
of butter paper.
• Dusting desired pollen grains on stigma
• Rebagging of the stigma
19. POLLEN-PISTIL INTERACTION
• COMPATIBLE POLLEN –
ACCEPTED
• INCOMPATIBLE POLLEN-
REJECTED
• POLLEN germinate on stigma
• Enter through micropyle into
one of synergids.
20. •
GERM PORES- POLLEN TUBE FORMATION
SYNERGIDS HAVE FILIFORM APPARATUS (FIBRILLAR THICKENINGS) – GUIDES THE
ENTRY OF POLLEN TUBE
21. DOUBLE FERTILISATION
• First male gamete (n) + egg cell(n) = zygote
(2n)
• Second male gamete(n) + two polar
nuclei(2n) = pen- primary endosperm
nucleus (3n)
• Central cell primary endosperm cell
(PEC)
SYNGAMY
Triple fusion
Syngamy+triple fusion =
double fertilisation
23. DEVELOPMENT OF ENDOSPERM
• Endosperm :- Nutritive tissue develop from
the PEC- primary endosperm cell.
• Three types-
1. NucleaR
2. CellulaR
3. Helobial
24. DEVELOPMENT OF EMBRYO (EMBEYOGENESIS)
• Zygote : Transverse division
• Two celled stage: Proembryo
• Globular Embryo
• Heart shaped Embryo
• Mature embryo
25. DICOT EMBRYO
• Dicot- Having two Cotyledons
• Consist of
1. Embryonal axis
2. Cotyledons
• Region of embryonal axis above cotyledons is called epicotyl
terminate into plumule(Future shoot)
• Regiom of embryonal axis below cotyledons is called hypocotyl
terminate into radicle(future root)
• Radicle covered with root cap
• Cotyledons store food and form seed leaves
26. MONOCOT EMBRYO
• Single cotyledon called scutellum
• The lower end of embryonal axis have radicle and rood cap
covered in coleorhiza
• Region of axis above cotyledons is epicotyl
• It has shoot apex and foliar structure called coleoptile.
28. TYPES OF SEED: ALBUMINOUS OR ENDOSPERMIC
NON-ALBUMINOUS OR NON-ENDOSPERMIC
SEED DORMANCY:- MATURE SEED LOSE WATER; BECOME DRY; SLOW
METABOLISM- THIS STATE OF INACTIVITY IS CALLED SEED DORMANCY.
29. FRUIT FORMATION
• Ovary develop into fruit
• Wall of ovary wall of fruit called pericarp
• Types of fruits-
1. True fruit- Mango
2. False fruit- apple
3. Parthenocarpic fruit- banana
30. APOMIXIS AND POLYEMBRYONY
• Apomixis- Production of seeds without
fertilisation
1. Parthenocarpy- Diploid egg cell without
meiosis develop into embryo.
2. Nucellar cells enter embryo sac and develop
into embryo.
• Polyembrony – Occurrence of more
than one embryo
• For example- Orange
