PRELIMS

Plant Morphology and Tissue System

Morphology is the study of form and features of plant parts (Roots, Stems, Leaves, Flowers, Fruits).

I. Root and Stem Modifications

• Root (Tap): Modification: Conical. Examples: Carrot
• ****: Modification: Napiform. Examples: Turnip, Beet
• ****: Modification: Fusiform. Examples: Radish
• Stem (Underground): Modification: Tuber. Examples: Potato
• ****: Modification: Corm. Examples: Saffron, Colocasia
• ****: Modification: Bulb. Examples: Onion, Garlic
• ****: Modification: Rhizome. Examples: Turmeric, Ginger

II. Reproductive Biology: Flowers and Fruits

• Androecium (Male): Unit is the Stamen; contains anther and pollen grains.
• Gynoecium (Female): Unit is the Carpel; contains ovary, style, and stigma.
• Pollination: Transfer of pollen to stigma (Self or Cross).
• Fertilization: In angiosperms, it is Triple Fusion; fertilized egg is the Zygote.
• Parthenocarpy: Seedless fruits developed without fertilization (e.g., Banana, Papaya).
• False Fruits: Developed from thalamus/calyx—not ovary (e.g., Apple, Pear, Jackfruit).

III. Edible Parts of Common Fruits

• Apple/Pear: Edible Part: Fleshy Thalamus. Fruit: Litchi. Edible Part: Aril
• Mango: Edible Part: Mesocarp. Fruit: Coconut. Edible Part: Endosperm
• Guava: Edible Part: Entire fruit. Fruit: Wheat. Edible Part: Starchy Endosperm
• Grapes/Tomato: Edible Part: Pericarp & Placenta. Fruit: Groundnut. Edible Part: Cotyledons
• Papaya: Edible Part: Mesocarp. Fruit: Banana. Edible Part: Mesocarp & Endocarp
• Orange: Edible Part: Juicy hair. Fruit: Cashew nut. Edible Part: Peduncle & Cotyledons

IV. Plant Tissue Systems

1. Meristematic Tissue: Cells capable of division.
   • Apical: Apex of root/stem (Growth in length).
   • Lateral: Width of root/stem (Secondary growth).
   • Intercalary: Base of internodes; allows regrowth (e.g., grass eaten by animals).
2. Permanent Tissue (Simple): Made of similar cell types; do not divide further.
   • Parenchyma: Living, thin-walled cells; found in soft plant parts; performs photosynthesis/storage.
   • Collenchyma: Living cells with thickened corners (pectin/cellulose); provides mechanical support and flexibility to young stems/leaf stalks.
   • Sclerenchyma: Dead cells with thick lignified walls; provides rigidity/mechanical strength (e.g., husk of coconut).
3. Permanent Tissue (Complex): Made of more than one type of cell, working as a unit.
   • Xylem: Conducts Water/Minerals and provides mechanical support.
     • Dendrochronology: The method of determining plant age by counting Annual Rings of xylem.
   • Phloem: Conducts Food from leaves to other parts.

UPSC Relevance

Plant anatomy and reproduction explain key agricultural outcomes.

• Edible Parts: Identifying that we eat the Aril of Litchi or the Endosperm of Coconut is a high-yield Prelims fact.
• Dendrochronology: A science-based method for evaluating environmental history and tree age.
• Horticulture: Understanding the difference between simple, aggregate, and composite fruits in the context of food processing.