Lecture: Morphology of Flowering Plants and Family Characteristics

Introduction

• Comprehensive lecture on morphology of flowering plants.
• Detailed discussion on NEET updated syllabus families.

Roots

Types of Roots

1. Tap Root: Primary root with secondary and tertiary branches.
2. Fibrous Roots: Short-lived primary root with numerous roots from the stem base (e.g., Wheat).
3. Adventitious Roots: Roots that arise from parts other than the radicle (e.g., Grass).

Structure of Roots

• Primary, secondary, and tertiary roots form the tap root system.
• Major functions: absorption of water and minerals, anchorage, and storage.
• Regions of Root: Root cap, meristematic zone, elongation zone, and maturation zone.
• Root Modification: Supportive roots (Prop roots in Banyan, Stilt roots in Sugarcane), Respiratory roots (Pneumatophores in Mangrove).

Stem

Characteristics

• Ascending part of the plant above the soil surface.
• Exhibits negative geotropism, holds branches, leaves, flowers, and fruits.
• Developed from the plumule of the embryo.

Growth

• Shoot Apical Meristem: Actively dividing cells at the shoot tip.
• Node & Internode: Nodes are points where leaves are attached; internodes are the regions between nodes.

Modifications and Functions

• Support: Tendrils (e.g., Cucumbers) and thorns (e.g., Bougainvillea).
• Storage: Potato, Ginger, Onion.
• Vegetative Propagation: Runners, stolons.

Leaf

Structure

• Parts: Leaf base, petiole, and lamina (leaf blade).
• Arrangement: Developed at nodes; displays acropetal arrangement (young leaves towards apex).
• Leaf Parts: Stipules may be present at leaf base.
• Venation: Arrangement of veins and veinlets (Reticulate in dicots, Parallel in monocots).
• Types: Simple and Compound (Pinnate or Palmate).

Function

• Main site for photosynthesis, gas exchange, and transpiration.

Inflorescence

• Arrangement of flowers on the floral axis.
• Types: Racemose (Indeterminate) and Cymose (Determinate).

Flower

Structure (Whorls)

1. Calyx: Sepals, usually green, protect the flower in the bud stage.
2. Corolla: Petals, usually colorful, attract pollinators.
3. Androecium: Stamens (anther and filament), male reproductive part.
4. Gynoecium: Carpels/pistils (stigma, style, ovary), female reproductive part.

Symmetry

• Actinomorphic: Regular or radial symmetry (Mustard, Datura).
• Zygomorphic: Bilateral symmetry (Pea, Bean).
• Asymmetrical: Cannot be divided into equal parts.

Position Types

• Hypogynous: Superior ovary (e.g., China rose).
• Perigynous: Half inferior ovary (e.g., Plum).
• Epigynous: Inferior ovary (e.g., Guava).

Fruit

Types

• True Fruit: Developed from ovary post-fertilization.
• Parthenocarpic Fruit: Seedless fruit without fertilization (e.g., Banana).
• Pericarp: Fruit wall, can be dry or fleshy; divided into epicarp, mesocarp, and endocarp in fleshy fruits.

Example

• Drupe: Single seed with hard endocarp (e.g., Mango, Coconut).

Seed

Types

• Dicot Seed: Two cotyledons, non-endospermic (e.g., Gram, Pea), exceptions (e.g., Castor is endospermic).
• Monocot Seed: One cotyledon, endospermic (e.g., Wheat, Maize).
• Structure: Seed coat (testa and tegmen), embryo (plumule, radicle), and endosperm.

Family Characteristics

Family: Brassiaceae

• Examples: Mustard

• Inflorescence: Racemose

• Floral Formula:

  EBR,

  • , Ꝟ, K(2+2), C4, A2+4, G(2)

• Placentation: Parietal

• Fruit: Silique or silicula

Family: Fabaceae

• Examples: Pea

• Inflorescence: Racemose

• Floral Formula:

  BR, %, Ꝟ💮, K(5), C1+2+(2), A(9)+1, G1

• Placentation: Marginal

• Fruit: Legume

Family: Solanaceae

• Examples: Brinjal, Potato

• Inflorescence: Solitary axillary or cymose

• Floral Formula:

  BR, +, Ꝟ, K(5), C(5), A5, G(2)

• Placentation: Axile

• Fruit: Berry or capsule

Family: Liliaceae

• Examples: Onion, Tulip

• Inflorescence: Racemose

• Floral Formula:

  BR, +, Ꝟ, P3+3, A3+3, G(3)

• Placentation: Axile

• Fruit: Capsule or berry

Family: Poaceae

• Examples: Wheat, Maize

• Inflorescence: Racemose

• Floral Formula:

  BR, +, Ꝟ, P2+3, A3 or 6, G(1)

• Placentation: Basal

• Fruit: Caryopsis

Family: Malvaceae

• Examples: Cotton, China Rose

• Inflorescence: Racemose

• Floral Formula:

  BR, +, Ꝟ, K(5), C5, Aᵢₙᵣ, G(⚸)5-Pₑᵣᵤₛ

• Placentation: Axile

• Fruit: Capsule or schizocarp

Family: Asteraceae (Compositae)

• Examples: Sunflower

• Inflorescence: Capitulum

• Floral Formula:

  For Disc Floret: BR, +, Ꝟ, K(Pappus), C(5), A(5), G(2⃣)

  For Ray Floret: BR, %, Ꝟ, K(pappus), C(5), A0, G(2)

• Placentation: Basal

• Fruit: Achene

Summary

• Detailed morphology and family characteristics of flowering plants covered.
• Key concepts such as types of roots, stems, leaves, inflorescence, flowers, fruits, and seeds discussed.
• Comparison and summary of different families based on their characteristics.

Important Note

• Use floral formulas to understand the structure of different flowers in various families.