Plant Leaves Structure and Functions

Structure of a Leaf

• Consists of:
  • Blade (lamina): the flat part of the leaf
  • Petiole (stem): connects the leaf to the plant
  • Stipules: small leaf-like structures at the base of the petiole

Functions of Leaves

• Photosynthesis: convert light energy into chemical energy
• Transpiration: regulate water loss and maintain turgor pressure
• Respiration: release oxygen and absorb carbon dioxide

Types of Leaves

• Simple leaves: have a single blade
• Compound leaves: have multiple leaflets attached to a central stalk
• Bi-pinnate leaves: have leaflets that are further divided into smaller leaflets

Leaf Venation

• Veins: vascular tissue that transport water, nutrients, and sugars
• Midvein (midrib): the central vein that runs along the length of the leaf
• Lateral veins: smaller veins that branch off from the midvein

Adaptations of Leaves

• Waxy coatings: prevent water loss
• Hairy leaves: reduce water loss and protect from insects
• Thick cuticles: reduce water loss and protect from extreme temperatures

Leaf Modifications

• Spines: reduce water loss and protect from herbivores
• Tendrils: aid in climbing and support
• Storage organs: store food and water (e.g., succulent leaves)

Structure of a Leaf

• A leaf consists of three main parts: blade (lamina), petiole (stem), and stipules.
• The blade is the flat part of the leaf where photosynthesis occurs.
• The petiole connects the leaf to the plant and supports the leaf.
• Stipules are small leaf-like structures at the base of the petiole.

Functions of Leaves

• Leaves perform photosynthesis, converting light energy into chemical energy.
• They regulate water loss and maintain turgor pressure through transpiration.
• Leaves release oxygen and absorb carbon dioxide through respiration.

Types of Leaves

• Simple leaves have a single blade, whereas compound leaves have multiple leaflets attached to a central stalk.
• Bi-pinnate leaves have leaflets that are further divided into smaller leaflets.

Leaf Venation

• Veins are vascular tissue that transport water, nutrients, and sugars throughout the leaf.
• The midvein, also known as the midrib, is the central vein that runs along the length of the leaf.
• Lateral veins are smaller veins that branch off from the midvein.

Adaptations of Leaves

• Waxy coatings, such as the cuticle, prevent water loss from the leaf.
• Hairy leaves reduce water loss and protect from insects.
• Thick cuticles reduce water loss and protect from extreme temperatures.

Leaf Modifications

• Spines, such as those found on cacti, reduce water loss and protect from herbivores.
• Tendrils, like those found on peas, aid in climbing and support.
• Storage organs, such as succulent leaves, store food and water for the plant.