Chapter: The Flower - Structure and Functions.
The flower is the most attractive and colorful part of a plant. However, its main purpose is not just beauty; it is the reproductive unit of the plant. In this note, we will learn about the four whorls of a flower.
1. The Four Whorls of a Flower.
A typical flower consists of four main parts arranged in rings or whorls.
- Calyx (Sepals): The outermost green, leaf-like structures are called sepals. They protect the flower when it is in the bud stage.
- Corolla (Petals): The second whorl consists of colorful petals. Their bright colors and fragrance attract insects for pollination.
- Androecium (Stamens): This is the male reproductive part of the flower. Each stamen is made of two parts: a long stalk called the filament and a swollen top called the anther which contains pollen grains.
- Gynoecium (Pistil): This is the female reproductive part located in the center. It is composed of the stigma, style, and ovary.
2. What is Pollination?
Pollination is the transfer of pollen grains from the anther to the stigma of a flower. This is a crucial step in the reproduction of plants.
Types of Pollination.
- Self-Pollination: This occurs when pollen falls on the stigma of the same flower.
- Cross-Pollination: This occurs when pollen is transferred to the stigma of a different flower of the same kind.
3. From Flower to Fruit.
After pollination, fertilization takes place inside the ovary. The ovary swells up and develops into a fruit, while the ovules inside it become seeds. Eventually, the petals and sepals dry up and fall off.
Chapter Summary.
To summarize, the flower is the reproductive organ of the plant. It has vegetative parts like sepals and petals, and reproductive parts like stamens and pistils. Understanding these parts helps us understand how fruits and seeds are formed.