3.4 Plant Fertilisation

1. The growth of the pollen tube is followed by fertilisation and soon leads to seed and fruit formation.

2. When the pollen grain lands on the stigma, it begins to germinate and a tube begins to grow down to the ovule.

3. Germination is usually only species specific.

4. The nucleus is then transferred through the tube down to the ovule, thus fertilizing it.

5. Pollen Nucleus + Ovule ---------> zygote/ Embryo

6. Outside of the ovule, a seed coat is formed, this is called the TESTA

7. Inside the seed coat, cotyledons are formed, these food stores for the seedling. This supports the plant until it develops its first set of leaves.

8. The plant uses a lot of its energy (sugars, protein) to thicken the walls of the ovary. This will soon develop to be a fruit that has been developed from the wall of the ovary (carpel)