class 12 th biology

1. SEXUAL REPRODUCTION IN FLOWERING
PLANTS

2. Stamen structure
Hibiscus stamen

3. Types of pollen grains
(A-C), Pollen grains or microspores.(A-B), Entire pollen grains;C, Pollen grain in section

4. Development of pollen grain

5. Development of pollen grain

6. Development of pollen grain

7. Pollen allergy
The signs and symptoms of pollen allergy
Sneezing, may be accompanied by a runny or clogged nose.
Itching eyes, nose, and throat.
Allergic shiners (dark circles under the eyes caused by
restricted blood flow near the sinuses)
The "allergic salute" (in a child, persistent upward rubbing
of the nose that causes a crease mark on the nose)
Watering eyes, Conjunctivitis (an inflammation of the
membrane that lines the eyelids, causing red-rimmed eyes).
asthma & bronchitis.

8. Example - pollen allergy
Parthenium argentatum Parthenium hysterophorus
(Carrot grass)

9. Pollen products
Increase the
Performance
of athletes
And
race horses

10. Pollen viability
◦ Rice flower

11. Flower of wheat

12. ◦ Rose leguminoceae

13. Mega sporangia - ovule

14. Megaspore mother cell
(megasporogenesis)

15. Megasporogenesis

16. Megasporogenesis

17. pollination
◦ What is pollination ?
◦ Pollination is the transfer of pollen from the anthers to the stigma.
The pollen may be transferred from the anthers to the stigma of
the same, or different flowers.

18. pollination

19. Cross pollination
Self pollination

20. Self pollination
◦ Requirements
◦ Synchrony in pollen release & stigma receptivity
◦ Anthers & stigma should lie close together

21. Chasmogamous flower
Exposed anthers
&
Exposed stigma

22. Cleistogamous flower

23. Cleistogamous flower
(autogamous)
Cleistogamous rapeseed flowers opened to varying degrees

24. Cleistogamous flower
(autogamous)
◦ Autogamous – no chance of cross pollination
◦ Produce assured seed-set even in the absence of pollinators
Is cleistogamy advantageous or disadvantageous?

25. Geitonogamy
Transfer of pollen grains
from
the anther to the
stigma of another
flower of the same plant
Genetically similar

26. Wind pollination

28. Well exposed stamen of corn cob

29. Feathery stigma
To trap air
borne pollen grains

30. Water pollination - hydro Philly
vallisneria
Female flowers
Reach the
Surface
of the water by
a long stalk.
Pollen grains are released
On to the surface of
water

31. hydrilla

32. era-sea grass
Pollen grains –long,
ribbon like, covered with
mucilaginous coverings
Water pollinated
flowers are not colorful.
Do not secrete nectar.
Female flowers remain
Submerged in water.
Pollen grains are
released inside
the water.

33. Animal pollinated flowers
◦ Bees
◦ Butterflies
◦ Flies
◦ Beetles
◦ Wasps
◦ Moths
◦ Birds
◦ Bats etc.,

34. Animal pollinated flowers

36. Insect pollinated flowers
◦ Large,colorful,fragrant
◦ Rich in nectar
◦ When the flowers are small - inflorescence

37. Pollination-animals
◦ Color of the flowers
◦ fragrance

38. Beetle pollinated flower
Flowers secrete foul
Odours to
Attract this animal

39. Flower of Amorphophallus-6ft ht
Provide safe place for
Laying eggs- a floral
Reward apart from
Nectar & pollen grains

40. Flower of Amorphophallus-6ft ht

41. Fertilization
in flowering
plants

42. Fertilization in plants

43. Fertilization in plants

44. Life cycle of a plant

45. Embryo development

47. Dicot embryo

48. Fruits

49. Advantages of seeds

50. Lupinus arcticus
Seed
germinated
after 10000
Years of
dormancy

51. Phoenix dactylifera-date palm
2000
years
Old
viable
seeds

52. Phoenix dactylifera-date palm

53. Apomixis
grass

54. A Model for Apomixis in Hieracium

56. apomixis

57. polyembryony

58. Seeds of orange