Morphology Of Flowering Plants Notes

Introduction

Morphology is the branch of biology that deals with the form and structure of organisms without consideration of function. In the context of flowering plants, morphology involves studying various structures such as roots, stems, leaves, flowers, fruits, and seeds. Understanding the morphology of flowering plants is crucial for identifying and classifying plants, which is an essential aspect of botany covered in the NEET syllabus.

Root System

The root system is the underground part of the plant that anchors it to the soil and absorbs water and nutrients.

Types of Roots

1. Taproot System
   • Structure: A single, thick primary root that grows deep into the soil, with smaller lateral roots.
   • Example: Carrot, radish.
   • Tip: Taproots are common in dicotyledonous plants.
2. Fibrous Root System
   • Structure: Numerous thin roots that spread out from the base of the stem.
   • Example: Grass, wheat.
   • Tip: Fibrous roots are typical in monocotyledonous plants.
3. Adventitious Roots
   • Structure: Roots that grow from parts of the plant other than the primary root, such as stems or leaves.
   • Example: Banyan tree (prop roots), maize (stilt roots).
   • Note: Adventitious roots can provide additional support.

Modifications of Roots

Roots can be modified for various functions:

• Storage Roots: Store food and nutrients.
  • Example: Sweet potato, beetroot.
• Respiratory Roots: Also known as pneumatophores, these roots help in gaseous exchange.
  • Example: Mangrove plants.
• Prop Roots: Provide additional support.
  • Example: Banyan tree.

Stem

The stem is the aerial part of the plant that supports leaves, flowers, and fruits.

Functions of Stem

• Support: Holds leaves, flowers, and fruits.
• Conduction: Transports water, minerals, and food.
• Storage: Stores nutrients.
• Photosynthesis: Green stems can perform photosynthesis.

Modifications of Stems

• Tendrils: For climbing.
  • Example: Grape vine.
• Thorns: For protection.
  • Example: Bougainvillea.
• Rhizomes: Underground stems for storage and vegetative reproduction.
  • Example: Ginger.
• Tubers: Swollen, underground stems for storage.
  • Example: Potato.

Leaf

Leaves are the primary photosynthetic organs of the plant.

Structure of a Leaf

• Blade (Lamina): The broad, flat part.
• Petiole: The stalk that attaches the leaf blade to the stem.
• Stipules: Small leaf-like structures at the base of the petiole.

Types of Leaves

• Simple Leaf: A single, undivided blade.
  • Example: Mango.
• Compound Leaf: The blade is divided into leaflets.
  • Example: Neem (pinnately compound), clover (palmately compound).

Modifications of Leaves

• Tendrils: For climbing.
  • Example: Pea plant.
• Spines: For defense.
  • Example: Cactus.
• Succulent Leaves: Store water.
  • Example: Aloe vera.
• Insectivorous Leaves: Trap insects for nutrition.
  • Example: Venus flytrap.

Inflorescence

Inflorescence refers to the arrangement of flowers on the floral axis.

Types of Inflorescence

1. Racemose Inflorescence
   • Structure: The main axis continues to grow, and flowers are borne laterally in an acropetal succession (younger flowers at the top).
   • Example: Mustard, lupin.
2. Cymose Inflorescence
   • Structure: The main axis terminates in a flower, and flowers are borne in a basipetal succession (younger flowers at the base).
   • Example: Jasmine, bougainvillea.

Flower

The flower is the reproductive unit of angiosperms.

Parts of a Flower

• Calyx: The outermost whorl, composed of sepals.
• Corolla: The whorl of petals.
• Androecium: The male reproductive part, composed of stamens.
• Gynoecium: The female reproductive part, composed of carpels.

Types of Flowers

• Complete Flower: Has all four whorls (calyx, corolla, androecium, gynoecium).
  • Example: Hibiscus.
• Incomplete Flower: Lacks one or more whorls.
  • Example: Grass flowers.

Fruit

Fruits are the mature ovary of a flower, containing seeds.

Types of Fruits

• Simple Fruits: Develop from a single ovary.
  • Example: Mango, tomato.
• Aggregate Fruits: Develop from multiple ovaries of a single flower.
  • Example: Strawberry.
• Multiple Fruits: Develop from ovaries of multiple flowers.
  • Example: Pineapple.

Seed

Seeds are the mature ovules that contain the embryo.

Structure of a Seed

• Seed Coat: Protective outer layer.
• Embryo: The young plant.
• Cotyledons: Seed leaves that store food.
• Endosperm: Nutrient-rich tissue.

Types of Seeds

• Monocot Seeds: Have one cotyledon.
  • Example: Maize.
• Dicot Seeds: Have two cotyledons.
  • Example: Bean.

Conclusion

Understanding the morphology of flowering plants is fundamental for the study of botany, especially for NEET aspirants. This knowledge helps in the identification, classification, and understanding of plant functions and adaptations.