Angiosperm fertilization, uniquely known as double fertilization, is a complex process involving two sperm cells from a pollen grain.
Double Fertilization: A Step-by-Step Guide
After pollination successfully transfers a pollen grain to the female reproductive structure (the carpel), fertilization begins. Here's how:
- Pollen Tube Formation: A pollen tube grows from the pollen grain, navigating through the style towards the ovule inside the ovary.
- Sperm Cell Delivery: The pollen tube delivers two sperm cells to the ovule.
- Zygote Formation: One sperm cell unites with the egg cell, resulting in a diploid zygote. This zygote will develop into the plant embryo.
- Endosperm Formation: The other sperm cell fuses with two polar nuclei in the central cell to create a triploid (3n) endosperm, which acts as the nutritive tissue for the developing embryo.
Key Aspects of Angiosperm Fertilization
| Feature | Description |
|---|---|
| Pollination | Transfer of pollen from anther to stigma. |
| Pollen Tube | Grows to deliver sperm to the ovule. |
| Sperm Cells | Two sperm cells are delivered, one for zygote, and one for endosperm. |
| Egg Cell | Unites with a sperm to form a diploid zygote. |
| Polar Nuclei | Two nuclei in the central cell that fuse with a sperm cell to form the triploid endosperm. |
| Double Fertilization | Unique process where two fertilization events take place: one forms the zygote, and one forms the endosperm. |
| Zygote | Diploid cell that will develop into the plant embryo. |
| Endosperm | Triploid nutritive tissue for the developing embryo. |
This dual fertilization process ensures that the developing embryo has an adequate food supply in the form of the endosperm. The information about the double fertilization process is sourced from the provided reference: Angiosperms, or flowering plants, undergo a unique process called double fertilization. After pollination brings a pollen grain to a flower's female reproductive structure (carpel), a pollen tube releases two sperm cells. One of these sperm cells unites with an egg cell to produce a diploid zygote.
Practical Insights:
- Evolutionary Advantage: Double fertilization is a key evolutionary adaptation in angiosperms, leading to efficient seed development.
- Variations: Although less common, variations in the process can occur in certain plant species.
- Agricultural Importance: Understanding this process is critical for plant breeding and crop improvement.
