Fertilisation Process

Fertilisation process
After Pollination pollen grain germinates after it comes into contact with stigma.
in response to the sugary fluid secreted by stigma
Pollen Tube grows out from each pollen grain.
male gamete enters pollen tube
As pollen tube grows it secretes enzymes to digest surrounding tissues of stigma and style.
- it also undergoes process of Mitosis allows growth/lengthening of pollen tube to allow male gamete to travel to ovum
thus pollen tube grows down style into the ovary
Pollen tube enters ovule through an opening in the ovule wall called micropyle
Within ovule tip of pollen tube absorbs sap and bursts releasing male gamete
Nucleus of male gamete fuses with the nucleus of the ovum to form the zygote
This is fertilisation
After fertilisation ovary develops into fruit and ovule develops into the seed.
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Note

all pollen grains germinate on stigma but only one will enter thru the micropyle to fertilise


Post Fertilisation Changes

After fertilisation, following changes take place in flower:

  • Ovary becomes fruit
  • Ovule becomes seed
  • Zygote become embryo. Embryo consists of the embryonic shoot, embryonic root, cotyledons
  • Petals, Style, Anthers wither and drop off
  • Stigma withers but remains on the fruit
  • Flower stalk fruit stalk