Weeks 7-10_Morphology of Flowering Plants_Student's copy

MORPHOLOGY AND ANATOMY OF FLOWERING PLANTS

  • Presented by: Christine Joy S. Luna

  • Institution: Polytechnic University of the Philippines, College of Science, Department of Biology, General Botany

WHAT IS MORPHOLOGY?

  • Definition: Study of the physical form and external structure of plants.

WHAT IS ANATOMY?

  • Definition: Study of the internal structure of plants, primarily at the cellular/microscopic level.

EXAMPLES OF FLOWERING PLANTS

  • Various examples based on student interaction.

MORPHOLOGY OF FLOWERING PLANTS

  1. Root

  2. Stem

  3. Leaf

  4. Flower

  5. Fruit

  6. Seed

ROOTS

  • Importance: Absorbing and anchoring organ, primarily developed from the radicle.

  • Typically grows downward and lacks nodes and leaves, generally found below ground.

ROOT SYSTEMS

Two Types:

  1. Tap Roots: Prominent in dicots, primary root is stout with secondary and tertiary roots.

  2. Fibrous Roots: Prominent in monocots, root length and diameter are similar.

GENERAL PARTS OF A ROOT

  • Radicle: First structure to emerge from a seed, develops into the primary root.

  • Lateral Roots: Branch out from the primary root.

  • Root Apical Meristem: Area at the root tip for new cell development.

ROOT CAP

  • Also called "calyptra"; protects the growing root tip.

  • Secretes mucilage for soil movement and may communicate with soil microbiota.

  • Contains statocytes for gravity perception.

ROOT TIP REGIONS

Region

Function

Root Cap

Protects apical meristem, gravity perception

Apical Meristem

Cell division, production of new cells

Elongation

Pushes root cap through soil

Maturation

Development of protoderm, procambium, and ground tissue

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PRIMARY ROOT ANATOMY

EPIDERMIS

  • Derived from protoderm; a single layer forming the outermost root tissue.

ROOT HAIRS

  • Lateral outgrowths from epidermal cells; absorb nutrients and water.

  • Density is greatest near the root tip for optimal nutrient absorption.

CORTEX

  • Derived from ground meristem; contains parenchyma cells for storage and air canals.

EXODERMIS & ENDODERMIS

  • Layers defining outer and inner cortex; endodermis contains casparian band for water regulation.

VASCULAR CYLINDER

  • Develops from procambium; contains xylem (for water transport) and phloem (for nutrient transport).

LATERAL ROOTS

  • Originates in the pericycle, connects with vascular system.

ADVENTITIOUS ROOTS

  • Arise from stem nodes; can perform various functions apart from typical roots.

SECONDARY GROWTH

  • Results in increased girth; occurs in woody plants and involves lateral meristems.

FUNCTIONS OF ROOTS

  1. Provides anchorage.

  2. Absorption and transportation of water and minerals.

  3. Storage of food.

MODIFICATIONS OF ROOTS

  • Roots may change in structure for different functions such as storage, respiration, and mechanical support.

TAP ROOT MODIFICATIONS:

  1. Fusiform Root: Swollen in the middle (e.g., Radish).

  2. Conical Root: Broader at base, tapers towards apex (e.g., Carrot).

  3. Napiform Root: Spherical stomach with tapered apex (e.g., Beet).

ADVENTITIOUS ROOT MODIFICATIONS:

  • For food storage (e.g., Sweet Potato) or mechanical support (e.g., Banyan trees).

STEMS

  • A supporting and conducting organ; divided into herbaceous (soft) and woody types.

  • Supports aerial parts: branches, leaves, flowers, and fruit.

  • Main functions include conducting, storing food, and providing support.

MODIFICATION OF STEMS

Underground Modifications

  • Tuber: Swollen underground stem (e.g., Potato).

  • Bulb: Short stem with fleshy scales (e.g., Onion).

  • Rhizome: Thickened underground stem with nodes (e.g., Ginger).

  • Corm: Short, swollen stem for food storage (e.g., Taro).

Aerial Modifications

  • Include various types like phyllocades, thorns, and tendrils for support or competition.

LEAVES

  • Lateral, flattened structures mainly responsible for photosynthesis.

  • Basic parts: Lamina (blade), petiole, and leaf base.

LEAF FUNCTIONS

  • Photosynthesis, gas exchange, protection of buds, water transport, and food storage.

LEAF VENATION

  • Types: Reticulate (e.g., Dicot) and Parallel (e.g., Monocot).

FLOWERS

  • Modified shoots for reproduction.

  • Comprised of whorls: calyx, corolla, androecium, and gynoecium.

PARTICIPATION IN REPRODUCTION

  • Perfect flowers contain both stamens and carpels; imperfect flowers contain only one.

  • Flower types include monoecious (both sexes) and dioecious (one sex).

FRUITS

  • Defined as mature ovaries, consist of three layers: epicarp, mesocarp, endocarp.

  • Types of fruits based on development include simple, dry indehiscent, dry dehiscent, and fleshy fruits.

REFERENCES

  • Carrillo-López, A., Yahia, E. M., in Postharvest Physiology and Biochemistry of Fruits and Vegetables (2019).

Note: This is an organized overview of key concepts from the content provided, focusing on morphology and anatomy of flowering plants.