The process of fertilization in plants varies based on how the pollen tube enters the ovule. The three main types are porogamy, chalazogamy, and mesogamy.
Types of Plant Fertilization
Here's a breakdown of each type:
Porogamy
- Definition: Porogamy is the most common type of fertilization in plants.
- Process: In this method, the pollen tube enters the ovule through the micropyle. The micropyle is a small opening in the ovule.
- Example: Most angiosperms (flowering plants) utilize porogamy.
Chalazogamy
- Definition: Chalazogamy is a less common type of fertilization.
- Process: Here, the pollen tube enters the ovule through the chalaza. The chalaza is the tissue at the base of the ovule where the funiculus (the stalk of the ovule) is attached.
- Example: Examples of plants that exhibit chalazogamy include some members of the Casuarina genus.
Mesogamy
- Definition: Mesogamy is another less common form of fertilization.
- Process: In this type, the pollen tube enters the ovule through the integuments or the funiculus. The integuments are the outer layers of the ovule, while the funiculus is the stalk that connects the ovule to the ovary wall.
- Example: Some plants of the Cucurbitaceae (gourd) family demonstrate mesogamy.
Summary Table
| Type | Pollen Tube Entry Point | Commonality | Example |
|---|---|---|---|
| Porogamy | Micropyle | Most Common | Most angiosperms |
| Chalazogamy | Chalaza | Less Common | Casuarina genus |
| Mesogamy | Integuments or Funiculus | Less Common | Some members of Cucurbitaceae family |
These three types showcase the different ways in which the pollen tube can reach the female gametophyte in plants to facilitate fertilization. The entry point influences the pathway of the sperm cells to the egg for the crucial process of reproduction.
