Parts of a flower (sepals, petals, stamens, pistil)

1. Introduction

1. The flower is the reproductive organ of angiosperms.
2. It consists of four main parts: sepals, petals, stamens, and pistil.
3. The arrangement of flowers on a plant is called inflorescence.

2. Structure of a Flower

1. A complete flower consists of four whorls arranged in layers.
2. Flowers can be unisexual (male or female) or bisexual (both male and female parts present).
3. The main parts of a flower include:

a) Sepals (Calyx)

1. The outermost whorl of the flower.
2. Usually green in color and leaf-like in structure.
3. Function: Protects the bud before it blooms.
4. Collectively, all sepals are called the calyx.

b) Petals (Corolla)

1. The second whorl inside the sepals.
2. Usually brightly colored to attract pollinators.
3. Function: Facilitates pollination by attracting insects and birds.
4. All petals together form the corolla.

c) Stamens (Androecium)

1. The male reproductive part of the flower.
2. Each stamen consists of:
   • Anther: Produces pollen grains containing male gametes.
   • Filament: A stalk that supports the anther.
3. All stamens together form the androecium.

d) Pistil (Gynoecium)

1. The female reproductive part of the flower.
2. Consists of three parts:
   • Stigma: The sticky tip where pollen lands.
   • Style: A tube that connects stigma to ovary.
   • Ovary: Contains ovules, which develop into seeds after fertilization.
3. All pistils together form the gynoecium.

3. Types of Flowers Based on Floral Parts

1. Complete Flower: Has all four whorls (e.g., Hibiscus).
2. Incomplete Flower: Missing one or more whorls (e.g., Corn).
3. Bisexual Flower: Has both stamens and pistils (e.g., Rose).
4. Unisexual Flower: Has either stamens (male) or pistil (female) (e.g., Papaya).

4. Inflorescence (Arrangement of Flowers)

1. The pattern in which flowers are arranged on a plant.
2. Two main types:

a) Racemose Inflorescence

1. Flowers grow in an acropetal order (newer flowers at the top).
2. Main axis continues to grow indefinitely.
3. Examples: Mustard, Gulmohar.

b) Cymose Inflorescence

1. Flowers grow in a basipetal order (newer flowers at the bottom).
2. Main axis ends in a flower, limiting further growth.
3. Examples: Jasmine, Sunflower.

5. Importance of Flower Structure

1. Understanding floral structure helps in plant classification.
2. Pollination and fertilization depend on flower structure.
3. Essential for crop breeding and horticulture.

6. Conclusion

1. A flower consists of sepals, petals, stamens, and pistils.
2. Flowers are arranged in different types of inflorescence.
3. Understanding flower morphology is important for botany and agriculture.