7. Getting to Know Plants
Introduction: Go outside and observe all the plants around you. Some are small, some very big, while some are just patches of green on the soil. Some have green leaves, while some have reddish ones. Some have huge red flowers, some have tiny blue ones.
Herbs, Shrubs and Trees
Plants can be classified into three categories based on their characters:
- Herbs: Plants with green and tender stems. Usually short and may not have many branches. (e.g., Tomato, Wheat).
- Shrubs: The stem branches out near the base. The stem is hard but not very thick. (e.g., Lemon, Rose).
- Trees: Very tall and have hard and thick brown stem. The stems have branches in the upper part, much above the ground. (e.g., Mango, Neem).
Creepers: Plants with weak stems that cannot stand upright and spread on the ground (e.g., Watermelon,
Pumpkin).
Climbers: Plants that take support on neighbouring structures and climb up (e.g., Money plant, Pea).
The Stem
The stem helps in upward movement of water. The water and minerals go to leaves and other plant parts attached to the stem.
ACTIVITY 2: Coloured Water
Observation: Put a stem with white flowers in a glass containing red ink water. The flowers turn red! This shows stem conducts water.
The Leaf
A leaf has a Petiole (part attached to stem) and Lamina (green expanded part). The lines on the leaf are called veins. The middle prominent line is the midrib.
Leaf Venation:
- Reticulate: Net-like design on both sides of midrib (e.g., Peepal, Rose).
- Parallel: Veins are parallel to one another (e.g., Grass, Maize, Wheat).
Transpiration: Water comes out of leaves in the form of vapour. This helps cool the plant.
Photosynthesis: Leaves prepare food in the presence of sunlight and a green substance (chlorophyll) using water and carbon dioxide.
The Root
Roots help in holding the plant firmly in the soil (Anchoring) and absorbing water/minerals.
- Taproot: One main root with smaller lateral roots. (Seen in plants with Reticulate Venation). E.g., Carrot, Balsam.
- Fibrous Roots: All roots seem similar and cluster at the base of the stem. (Seen in plants with Parallel Venation). E.g., Grass, Wheat.
The Flower
The beautiful part of the plant!
- Sepals: Small green leaf-like structures acting as protection for the bud.
- Petals: Prominent, coloured parts to attract insects.
- Stamens: Male part. Consists of Anther (top) and Filament.
- Pistil: Female part (innermost). Consists of Stigma (top), Style (neck), Ovary (swollen bottom).
Ovary: Contains small bead-like structures called ovules.
Chapter Summary
- Plants are usually grouped into herbs, shrubs and trees, and creepers and climbers.
- The stem bears leaves, flowers and fruits.
- Leaf usually has a petiole and lamina.
- The pattern of veins on the leaf is called venation. It can be reticulate or parallel.
- Leaves give out water vapour through the process of transpiration.
- Green leaves make their food by the process of photosynthesis using carbon dioxide and water in the presence of sunlight.
- Roots are mainly of two types: tap root and fibrous root.
- Plants having leaves with reticulate venation have tap roots while plants having leaves with parallel venation have fibrous roots.
- The stem conducts water from roots to the leaves (and food from leaves to other parts).
- The parts of a flower are sepals, petals, stamens and pistil.
Exercise Q1: Correct the statements
- Stem absorbs water and minerals from soil. -> Roots absorb water and minerals from soil.
- Leaves hold the plant upright. -> Stem holds the plant upright.
- Roots conduct water to the leaves. -> Stem conducts water to the leaves.
- The number of petals and stamens in a flower is always equal. -> Usually not equal.
- If the sepals of a flower are joined together, its petals are also joined together. -> Not necessarily.
- If the petals of a flower are joined together, then the pistil is joined to the petal. -> Not necessarily.
Exercise Q2
Q: Draw: (a) A leaf, (b) A taproot, (c) A flower.
(Note: Practice drawing from your textbook figures 7.8, 7.17 and 7.23)
Exercise Q3
Q: Can you find a plant in your house or in your neighborhood which has a long but weak stem? Write its name. In which category will you place it?
Exercise Q4
Q: What is the function of a stem?
- Hold the plant upright.
- Bear leaves, flowers, and fruits.
- Conduct water and minerals from roots to leaves.
- Conduct food from leaves to other parts.
Exercise Q5
Q: Which of the following leaves have reticulate venation? Wheat, tulsi, maize, grass, coriander (dhania), china rose.
Exercise Q6 & Q7: Roots and Venation
- If a plant has fibrous roots, its leaves likely have Parallel Venation.
- If a plant has leaves with reticulate venation, it will likely have Tap Roots.
Exercise Q8
Q: Is it possible to find out whether a plant has taproot or fibrous roots without pulling it out?
Exercise Q9
Q: Write the names of the parts of a flower.
Exercise Q10: Plants with flowers
Exercise Q11
Q: Name the part of plant which produces food. Name the process.
Exercise Q12
Q: In which part of flower you will find the ovary?
Exercise Q13
Q: Name two plants in which one has joined sepals and the other has separate sepals.
- Joined Sepals: Hibiscus (China Rose), Cotton, Dhatura
- Separate Sepals: Rose, Lotus
Key Facts and Definitions
- Chlorophyll: Green pigment present in leaves, helps in photosynthesis.
- Photosynthesis: Process by which green plants make their own food using sunlight, carbon dioxide, and water.
- Transpiration: Loss of water in the form of vapour from the leaves.
- Veins: Network of lines on the leaf blade.
- Midrib: The prominent vein in the middle of the leaf.
| Part | Description |
|---|---|
| Sepals | Small leaf-like green structures protecting the bud. |
| Petals | Brightly colored part to attract insects. |
| Stamen | Male part. Contains Anther (pollen sac) and Filament. |
| Pistil | Female part. Contains Stigma, Style and Ovary. |
- Reticulate Venation: Veins form a net-like design (e.g. Peepal, Rose).
- Parallel Venation: Veins are parallel to one another (e.g. Grass, Wheat).