Characteristics, classification (monocots and dicots), structure

1. Introduction

1. Angiosperms are the most advanced and diverse group of plants.
2. They are also known as flowering plants because they produce flowers.
3. Angiosperms are characterized by enclosed seeds inside a fruit.
4. They belong to the division Angiospermae under the kingdom Plantae.
5. They are found in almost all habitats, including land, water, and extreme conditions.

2. Characteristics of Angiosperms

1. Possess well-developed roots, stems, leaves, flowers, and fruits.
2. Exhibit vascular tissue with well-defined xylem (with vessels) and phloem (with sieve tubes).
3. Reproduce via flowers, which contain male and female reproductive structures.
4. Undergo double fertilization, a unique feature among plants.
5. Produce seeds enclosed within fruits.
6. Exhibit a dominant sporophytic phase with a highly reduced gametophyte.
7. Show a variety of pollination mechanisms (wind, water, insects, birds, etc.).

3. Classification of Angiosperms

Angiosperms are broadly classified into two major groups:

3.1 Monocotyledons (Monocots)

1. Have one cotyledon in the seed.
2. Leaves show parallel venation.
3. Vascular bundles are scattered in the stem.
4. Root system is usually fibrous.
5. Flowers have trimerous symmetry (petals in multiples of 3).
6. Examples: Wheat, Rice, Maize, Banana, Palm.

3.2 Dicotyledons (Dicots)

1. Have two cotyledons in the seed.
2. Leaves show reticulate venation.
3. Vascular bundles are arranged in a ring inside the stem.
4. Root system is usually taproot.
5. Flowers have tetramerous or pentamerous symmetry (petals in multiples of 4 or 5).
6. Examples: Mango, Rose, Pea, Sunflower.

4. Structure of Angiosperms

4.1 Root System

1. Functions in absorption of water and minerals.
2. Anchors the plant in the soil.
3. Types:
   • Taproot (in dicots, e.g., Mango).
   • Fibrous root (in monocots, e.g., Grass).
   • Adventitious root (e.g., Banyan tree).

4.2 Stem

1. Provides structural support and transports nutrients.
2. Can be herbaceous (soft, e.g., Sunflower) or woody (hard, e.g., Mango tree).
3. Has vascular bundles for transport of water and food.

4.3 Leaf

1. Primary site for photosynthesis.
2. Shows different types of venation:
   • Parallel venation (monocots).
   • Reticulate venation (dicots).

4.4 Flower

1. Reproductive organ of angiosperms.
2. Consists of:
   • Calyx (sepals) – Protects the flower bud.
   • Corolla (petals) – Attracts pollinators.
   • Androecium (stamens) – Male reproductive part.
   • Gynoecium (carpels) – Female reproductive part.
3. Undergoes pollination (self or cross-pollination).

4.5 Fruit

1. Develops from the ovary after fertilization.
2. Protects the seeds and aids in their dispersal.

4.6 Seed

1. Contains the embryo which develops into a new plant.
2. Has stored food in cotyledons (dicots) or endosperm (monocots).

5. Economic Importance of Angiosperms

1. Food source: Major cereals (Wheat, Rice), vegetables, and fruits.
2. Medicinal plants: Many angiosperms have medicinal properties (e.g., Neem, Tulsi).
3. Timber and wood: Used for construction (e.g., Teak, Sal, Rosewood).
4. Fibers: Cotton, Jute, and Hemp are used in textiles.
5. Oil production: Sunflower, Mustard, and Coconut provide edible oils.
6. Ornamental plants: Roses, Lilies, and Orchids are used for decoration.

6. Conclusion

1. Angiosperms are the largest group of plants with advanced reproductive structures.
2. They show great diversity in habitat, structure, and function.
3. Angiosperms provide food, medicine, timber, and fiber, making them essential for human survival.