Quick Revision Notes & Formula Sheet

Class: 6th Science
Chapter: Getting to Know Plants (पौधों को जानिए)

### 1. Introduction & Classification of Plants (पौधों के प्रकार)

Plants are usually grouped into three categories based on their height, stem nature, and branches:

• Herbs (शाक):
  • Characteristics: Plants with green and tender stems. Usually short and may not have many branches.
  • Examples: Grass, Tomato, Wheat, Paddy.
• Shrubs (झाड़ी):
  • Characteristics: Plants with hard stems branching near the base. The stem is not very thick.
  • Examples: Lemon, Tulsi, Rose.
• Trees (वृक्ष):
  • Characteristics: Very tall plants with hard and thick brown stems (trunk). Stems have branches in the upper part, much above the ground.
  • Examples: Mango, Neem, Banyan.

### 2. Special Categories of Plants (विशेष प्रकार के पौधे)

• Creepers (विसर्पी लता): Plants with weak stems that cannot stand upright and spread on the ground.
  • Example: Watermelon, Pumpkin.
• Climbers (रोही / पर्वतारोही): Plants that take support of neighboring structures and climb up.
  • Example: Money plant, Grapevine, Pea plant.

### 3. Parts of a Plant (पोधों के भाग)

A standard flowering plant consists of two main systems:

1. Root System (जड़ तंत्र): Underground part (Roots).
2. Shoot System (प्ररोह तंत्र): Above-ground parts (Stem, Leaves, Flowers, Fruits).

### 4. Key Plant Parts and Their Functions (मुख्य भाग और उनके कार्य)

A. Stem (तना)

• Function:
  • Bears leaves, flowers, and fruits.
  • Conducts water and minerals from roots to leaves (upward movement).
  • Transports food from leaves to other parts of the plant.

B. Leaf (पत्ती)

• Main Parts:
  • Petiole (पर्णवृंत): The part of the leaf by which it is attached to the stem.
  • Lamina (फलक): The broad, green part of the leaf.
  • Veins (शिराएँ): Lines on the leaf providing a network for transport.
  • Midrib (मध्य शिरा): A prominent vein in the middle of the leaf.
• Leaf Venation (शिराविन्यास - Arrangement of veins):
  • Reticulate (जालिका रूपी): Net-like design on both sides of midrib (e.g., Mango, Hibiscus). Note: Usually found in plants with tap roots.
  • Parallel (समांतर): Veins are parallel to one another (e.g., Grass, Wheat, Maize). Note: Usually found in plants with fibrous roots.
• Functions of Leaves:
  • Photosynthesis (प्रकाश संश्लेषण): Leaves prepare food using water, carbon dioxide, sunlight, and green pigment (Chlorophyll / पर्णहरित).
  • Transpiration (वाष्पोसर्जन): Release of water vapor from leaves into the air through tiny pores called Stomata (रंध्र).

C. Root (जड़)

• Main Types:
  • Tap Root (मूलांकुर / मूसला जड़): One main root (called the primary root) with smaller lateral roots (secondary roots). (e.g., Carrot, Beetroot, Gram).
  • Fibrous Root (झगड़ा जड़ / रेशेदार जड़): No main root; all roots seem similar, arising in a cluster from the base of the stem. (e.g., Wheat, Grass, Maize).
• Functions of Roots:
  • Anchor the plant firmly in the soil.
  • Absorb water and minerals from the soil.
  • Some roots store food (e.g., Carrot, Radish, Sweet potato).

D. Flower (फूल / पुष्प)

• Main Parts (from outside to inside):
  • Sepals (बाह्यदल): Green, leaf-like outermost part that protects the bud.
  • Petals (दल / पंखुड़ी): Brightly colored parts that attract insects for pollination.
  • Stamen (पुंकेसर - Male part): Made up of Anther (परागकोश) and Filament (तंतु). Produces pollen grains.
  • Pistil / Carpels (स्त्रीकेसर - Female part): Innermost part made up of Stigma (वर्तिकाग्र), Style (वर्तिका), and Ovary (अंडाशय).
• Ovary Structure: The swollen lower part of the pistil containing tiny bead-like structures called Ovules (बीजांड).

### Important Scientific Terms to Remember (महत्वपूर्ण शब्द)

1. Photosynthesis: The process by which green plants make their food using sunlight, water, and $CO_2$.
2. Chlorophyll: Green pigment present in leaves that traps sunlight.
3. Transpiration: Loss of water in the form of vapor from the aerial parts of plants.
4. Ovule: Small bead-like structures inside the ovary of a flower.