The document summarizes the parts of a flower and the process of sexual reproduction in flowering plants. It describes the key parts of a flower including the pistil (female) containing the stigma, style, and ovary, and the stamen (male) containing the filament and anther. It explains that the ovary houses the ovules containing egg cells, and the anther produces pollen. The document also summarizes the processes of megasporogenesis and megagametogenesis that produce the egg in the ovule, and microsporogenesis and microgametogenesis that produce pollen grains in the anther. Fertilization occurs when pollen lands on the stigma and a pollen tube delivers

1. Parts of a Flower
Unit Four, Lesson 4.2
By Margielene D. Judan

2. Lesson Outline
 Introduction: Sexual Reproduction
 Flowering Plants
 Parts of a Flower

3. Reproduction
 Reproduction is the creation of “new
individuals” from existing individuals.

4. Two Types of Reproduction
 Sexual – involves sex cells (egg, sperm)
 Asexual – does not involve sex cells

5. Refer to p.125
In asexual
reproduction, the
parent cell is SINGLE
AND DIVIDING.
(ex. amoeba, hydra,
fungi, bacteria, etc.)

6. Refer to p.125
In sexual reproduction,
the offspring are
genetically identical
(exact clones) to their
parents.
(ex. humans,
elephants, dogs, fishes,
plants, etc.)

8. Sexual Reproduction
 Involves union of gametes
 Gametes = sperm (male) +
egg (female)
 Trivia: The egg is the largest
cell in the human body
while the sperm is the
smallest.

9. Sexual Reproduction
 Sperm – mobile and small
 Egg – immobile and large
 During fertilization, they
unite (n + n) to form a
diploid (2n) zygote
(fertilized egg)

10. Nonflowering Plants
 They are called gymnosperms (we will not
discuss them).

11. Flowering Plants
 Comprises 90% of plant species
 Classified as either:
1. Angiosperms – have seeds enclosed in
ovary
2. Anthophytes – plants that produce flowers.
They have an ovary that’s part of the
flower

12. Flowers
 Reproductive organs/structures of a plant
 Most flowers are hermaphrodites (contains
both male and female sex organs)

13. Parts of a Flower
 Corolla
 Calyx
 Stamen (male)
 Pistil (female)
 Receptacle
 Peduncle
(Be sure to be able to memorize and label each part)

15. Accessory Parts – function mainly for
support, protection and attraction
• Corolla
• Calyx
• Receptacle
• Peduncle

16. Corolla
 Comprises of the
petals
 Have various
shapes, sizes, and
colors
 Function:
protection,
attraction

17. Calyx
 Comprises of
sepals (typically
green)
 Leaf-like
 Function: Protect
the flower when
it was still young
sepal

18. Receptacle
 Also called torus
 Function:
Supports the
entire flower
(base of the
flower)
receptacle
calyx

19. Peduncle
 Also called stalk
 Function:
Connects the
flower to the
branch or stem.
peduncle

20. Reproductive Parts – for reproduction;
main parts of a flower
1. Stamen (male)
2. Pistil (female)

21. Stamen
 The male reproductive
organ
 Collectively called
androecium (collective
noun)
 Composed of two parts:
1. Anther
2. Filament

22. Anther
 Expanded lobular
structure at the
end of the
filament
 Function:
Produces pollen
(male sex cell)

23. Filament
 Function: Stalk
that supports and
holds the anther

24. Pistil or carpel
 The female reproductive
organ
 Collectively called
gynoecium (collective noun)
 Composed of three parts:
1. Stigma
2. Style
3. Ovary

25. Stigma
 Swollen tip of the
pistil
 Function:
Covered by sticky
substance for
pollen grains to
adhere (stick) to
stigma Pollen grains
(purple dots)

26. Style
 Function: Long,
slender tube that
connects the
stigma to the
ovary
 Acts as a
conveyor (carrier
from one place to
another) of pollen
grains
style

27. Ovary
 Enlarged basal
portion of the
pistil
 Function: Houses
the ovule
 The ovule houses
the egg cell

28. Ovary
In cross section, internal parts of the ovary can
be seen:
Carpel
Locule
Ovule
Funiculus
Placenta

29. Ovary
Carpel –
segment or
partition that
comprises an
ovary
Ovary wall –
supports the
ovary Ovary with 3 carpels

30. Ovary
Locule – space
or cavity within
the carpel
An ovary with 3
carpels has also
3 locules
room-like locules

31. ovules
(2 ovules
per
locule)
Cross-section of a
plant ovary carpel

32. Ovary
Ovary core –
solid structure
at the center
Placenta – the
edge of the
core; nourishes
the egg
core (yellow);
placenta (green)
Visual representation
core
placenta
placenta
core

33. Ovary
Finuculus –
short stalk that
connects the
ovule and
placenta
finiculus
finiculus

34. Ovary
Ovule –
produces the
egg
(2 ovules per
lenticel)
ovule
ovule
ovule

37. Cross-section of an ovule
The ovule has the following parts:
1. Integument - 2 layer protective coat
2. Nucellus – mass of tissue consisting of
meristematic (dividing) cells
3. Funiculus
4. Embryo sac – contains the egg

38. (ovary sac) (ovary sac)

39. Development of Gametophytes
(Egg) Two Stages
1. Megasporogenesis (genesis = beginning/creation) –
creation of megaspores
2. Megagametogenesis – creation of the gametes (egg)

40. Development of Gametophytes
(Egg)
1. Megasporogenesis
A. Ovule produces megaspore
mother cell (2n).
B. Megaspore mother cell
(2n) produces 4
megaspores (n) via a two-
time meiosis.
C. 3 megaspores die and only
one is left to continue.
2n
n n
meiosis
n n
meiosis
n n
meiosis

41. Development of Gametophytes
(Egg)
1. Megagametogenesis
A. The surviving
megaspore divides
via mitosis 3 times,
forming 8 haploid
(n) cells)
n megaspore
n n
n n n n
nnnnnnnn
mitosis
mitosis mitosis
mitosismitosismitosismitosis
8 haploid (n) cells

42. Egg Development in Ovule
B. Among the eight cells:
 3 cells migrate near the micropyle.
The one at the center becomes the
egg while the other two becomes
the synergid cells.
 The other 3 migrate on the opposite
pole and become antipodal cells.
 The remaining 2 cells are naked (no
membrane) and remains at the
center to become the polar nuclei.
micropyle
egg
synergidsynergid
antipodal
polar nuclei

44. Egg Development in Ovule
C. These 8 cells form
the inside of the
embryo sac and are
ready to be
fertilized by a
pollen (from the
male).

46. Pollen Development in the
Anther (Male)
Like egg development, pollen
development undergoes meiosis and
mitosis to produce pollen grains.
The product is 2 pollen grains.
1. Microsporogenesis – creation of
microspore
2. Microgametosgenesis – creation
of male gametes (pollen)

48. Assignment:
p. 143 (Check Your Knowledge A: #s 1-10)

49. Sources:
 Science Links 7