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MODULE 6.1: EXTERNAL FEATURES OF FLOWERING PLANTS
Introduction
Flowering plants, also known as angiosperms, are plants that produce flowers and seeds. They are the most common plants found in our environment and are very important to humans and animals because they provide food, shelter, oxygen, and raw materials. A typical flowering plant is made up of four main external parts: roots, stem, leaves, and flowers. Each of these parts performs specific functions that help the plant to grow, survive, and reproduce.
1. Roots
Roots are the part of the plant that usually grow below the ground. They help to anchor the plant firmly in the soil and also absorb water and mineral salts from the soil.
Functions of Roots
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Roots absorb water and mineral salts needed by the plant for growth.
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They anchor the plant firmly in the soil, preventing it from being blown away by wind.
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Some roots store food, for example cassava, carrot, and sweet potato.
Types of Roots
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Tap root system: Has one main root with smaller branches (e.g. mango, bean plant).
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Fibrous root system: Has many thin roots of equal size (e.g. maize, rice).
2. Stem
The stem is the part of the plant that grows above the ground and supports the leaves, flowers, and fruits.
Functions of the Stem
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It supports the plant and holds the leaves and flowers upright.
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It transports water and mineral salts from the roots to other parts of the plant.
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It transports manufactured food from the leaves to other parts of the plant.
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In some plants, the stem stores food (e.g. sugarcane).
Types of Stems
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Soft stems (herbaceous plants) such as tomato.
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Hard stems (woody plants) such as mango and orange trees.
3. Leaves
Leaves are usually flat and green parts of the plant attached to the stem.
Functions of Leaves
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Leaves manufacture food for the plant through the process of photosynthesis.
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They allow gaseous exchange (oxygen and carbon dioxide).
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Leaves lose excess water through transpiration.
Parts of a Leaf
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Leaf blade (lamina)
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Midrib
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Veins
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Petiole (leaf stalk)
4. Flowers
Flowers are the reproductive parts of flowering plants. They are responsible for the production of seeds.
Main Parts of a Flower
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Sepals: protect the flower bud.
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Petals: attract insects for pollination.
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Stamen (male part): produces pollen grains.
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Pistil or carpel (female part): produces ovules.
Importance of Flowers
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They help in reproduction.
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They lead to the formation of fruits and seeds.
Learning Outcome Achieved:
At the end of this module, the teacher should be able to draw, illustrate, and label the parts of a flowering plant correctly.
MODULE 6.2: LIFE CYCLE STAGES OF FLOWERING PLANTS
Introduction
The life cycle of a flowering plant refers to the various stages the plant goes through from the time a seed is planted until it produces new seeds. The life cycle is continuous and includes germination, growth, flowering, and seed formation.
1. Germination
Germination is the process by which a seed begins to grow into a new plant under suitable conditions.
During germination:
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The seed absorbs water and swells.
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The seed coat breaks open.
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The root (radicle) grows downward.
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The shoot (plumule) grows upward.
2. Growth
Growth is the stage where the young plant increases in size and develops leaves, stems, and roots.
At this stage:
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The plant produces more leaves.
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Roots grow deeper into the soil.
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The plant begins to make its own food through photosynthesis.
3. Flowering
Flowering is the stage where the plant produces flowers.
Importance of Flowering:
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Flowers allow pollination and fertilization to take place.
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They prepare the plant for seed formation.
4. Seed Formation
After fertilization, seeds are formed inside fruits.
At this stage:
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The ovules develop into seeds.
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The ovary develops into a fruit.
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Seeds are dispersed to grow into new plants.
Learning Outcome Achieved:
The teacher should be able to explain each stage of the life cycle of flowering plants clearly with examples.
MODULE 6.3: FACTORS AFFECTING THE LIFE CYCLE OF FLOWERING PLANTS
Introduction
The growth and development of flowering plants depend on certain environmental factors. Without these factors, plants cannot complete their life cycle successfully.
1. Water
Water is essential for plant growth.
Importance of Water:
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Helps in germination of seeds.
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Transports nutrients within the plant.
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Required for photosynthesis.
Lack of water can cause plants to wilt and die.
2. Sunlight
Sunlight provides energy needed for photosynthesis.
Importance of Sunlight:
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Helps plants manufacture food.
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Affects flowering and fruiting.
3. Soil
Soil provides support and nutrients to plants.
Importance of Soil:
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Holds the roots firmly.
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Supplies mineral salts.
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Provides water to plants.
4. Air
Air is important for respiration and photosynthesis.
Importance of Air:
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Oxygen is needed for respiration.
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Carbon dioxide is needed for photosynthesis.
Learning Outcome Achieved:
The teacher should be able to state and explain factors affecting plant growth.
MODULE 6.4: GERMINATION
Introduction
Germination is the process by which a seed develops into a young plant. It marks the beginning of a plant’s life cycle.
Types of Germination
1. Epigeal Germination
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The cotyledons grow above the soil surface.
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Example: Bean plant.
2. Hypogeal Germination
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The cotyledons remain below the soil surface.
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Example: Maize.
Conditions Necessary for Germination
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Water: Softens the seed coat and activates enzymes.
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Air (Oxygen): Needed for respiration.
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Warmth: Helps enzymes work properly.
Process of Germination
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The seed absorbs water.
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The seed coat splits.
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The radicle emerges first.
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The plumule grows upward to form the shoot.
