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SEXUAL REPRODUCTION IN FLOWERING PLANTS

SEXUAL REPRODUCTION IN FLOWERING PLANTS. CHAPTER 1. flowers are morphological and embryological marvels and the sites of sexual reproduction. In the flower the male and female reproductive structures, the androecium and the gynoecium differentiate and develop.

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SEXUAL REPRODUCTION IN FLOWERING PLANTS

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  1. SEXUAL REPRODUCTION INFLOWERING PLANTS CHAPTER 1

  2. flowers are morphological and embryological marvelsand the sites of sexual reproduction

  3. In the flower the male and female reproductive structures, the androecium and the gynoecium differentiate and develop. the androecium consists of a whorl of stamens representing the male reproductive organ and the gynoecium represents the female reproductive organ. PRE-FERTILISATION: STRUCTURES AND EVENTS

  4. typical angiosperm anther is bilobed with each lobe having two theca, i.e., they are dithecous four microsporangia Stamen, Microsporangium and Pollen Grain

  5. Structure of microsporangium Microsporogenesis The process of formation of microspores from a pollen mother cell through meiosis

  6. Pollen grain pollen grains represent the male gametophytes Pollen grains are rich in nutrients

  7. The Pistil, Megasporangium (ovule) and Embryo sac The gynoecium represents the female reproductive part of the flower. multicarpellary monocarpellary

  8. syncarpous). apocarpous

  9. The Megasporangium (Ovule) The ovule is a small structure attached to the placenta by means of a stalk called funicle.

  10. Megasporogenesis The process of formation of megaspores from the megaspore mother cell is called megasporogenesis

  11. Autogamy- pollination is achieved in the same flower Pollination Chasmogamy- Oxalis Cliestogamy- Oxalis

  12. Xenogamy- between different plants Geitonogamy- pollen from the anther to the stigma of another flower of the same plant.

  13. Abiotic and biotic Wind pollination- pollen grains are light and non-sticky. Well exposed stamens Water pollination- long ribben like, mucilage covering Agents of pollination

  14. Animal pollinated Flowers are large, colorful, fragrant and rich in nectar. Small flowers are clustered into inflorescence Yucca and moth Pollen robbers

  15. Outbreeding devices Continued self pollination result in inbreeding depression. Receptivity is not synchronised Anther and stigma are placed in different positions Self incomactibility Unisexual flowers

  16. Pollen pistil interaction If the pollen is of the right type pistill will allow germintaion- communicate through chemicals Pollen grains are shed at two celled stage

  17. Artificial hybridisation Emasculation and bagging

  18. Double fertilization syngamy and triple fusion- embryo and edoseprm

  19. Post fertilization changes ’ Endosperm, embryo development, maturation of ovules into seeds and ovary into fruit Free nuclear endosperm Endosperm is completely used up- pea, groundnut Endosperm is not completely used up- coconut, castor

  20. embryo

  21. seed A fertilized ovule Albuminous and non albuminous seeds Remnants of nucellus- perisperm

  22. Fruit A mature ovary Pericarp- walls of fruit from integuments dormancy False fruits Parthenocarpic fruits

  23. Apomixis and Polyembryony

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